80MGF Series
Transcript of 80MGF Series
Page 1 © 1998 Lennox Industries Inc.
Corp. 9801−L2
80MGFService Literature Revised 08−2004
80MGF SERIES UNITS80MGF series units are mid−efficiency gas furnaces
manufactured with tubular heat exchangers formed of alu-
minized or stainless steel. 80MGF units are available in
heating capacities of 45,000 to 140,000 Btuh and cooling
applications up to 5 tons. Refer to Engineering Handbook
for proper sizing.
Units are factory equipped for use with natural gas. A kit is
available for conversion to LPG operation. All 80MGF units
built proir to September 98 use electronic (direct spark) igni-
tion. 80MGF−11 model units are equipped with the Lennox
SureLight ignition system. The 80MGFX unit meets the
California Nitrogen Oxides (NOx) Standards and California
Seasonal Efficiency requirements. All units use a redun-
dant gas valve to assure safety shut−off as required by
A.G.A. or C.G.A.
The heat exchanger, burners and manifold assembly can
easily be removed for inspection and service by simply dis-
connecting gas, unplugging wiring harness and spark wires
and removing four screws holding the heat exchanger in
place. Then the heat exchanger slides out of the cabinet.
All specifications in this manual are subject to change.
Procedures outlined in this manual are presented as a rec-
ommendation only and do not supersede or replace local
or state codes. In the absence of local or state codes, the
guidelines and procedures outlined in this manual (except
where noted) are recommended only and do not constitute
code.
Units may be installed in upflow, downflow or horizontal
position. The heat exchanger is designed for upright or
horizontal use only. When the unit is installed in the down-
flow position, the heat exchanger is field removed and re-
installed so it is upright when the cabinet is inverted. No
field conversion is required when the unit is installed in the
horizontal position.
TABLE OF CONTENTS
Introduction 1. . . . . . . . . . . . . . . . . . . . . . . .
Specifications 2. . . . . . . . . . . . . . . . . . . . . .
Blower Data 5. . . . . . . . . . . . . . . . . . . . . . .
Parts Identification 7. . . . . . . . . . . . . . . . . .
I Unit Components 9. . . . . . . . . . . . . . . . . .
II Installation 19. . . . . . . . . . . . . . . . . . . . . . .
III Start Up 19. . . . . . . . . . . . . . . . . . . . . . . . .
Preliminary Seasonal Checks 20 . . . . .
Heating Start Up 20. . . . . . . . . . . . . . . .
IV Heating System Service Checks 20. . .
V Typical Operating Characteristics 22. . .
VI Maintenance 24. . . . . . . . . . . . . . . . . . . .
VII Wiring and Sequence of Operation 26.
VIII SureLight Control Troubleshooting 40.
Page 2
SPECIFICATIONSModel No. 80MGF2(X)-45 80MGF2-60 80MGF3(X)-60 80MGF2-75 80MGF3(X)-75
Input Btuh (kW) 45,000 (13.2) 60,000 (17.6) 75,000 (22.0)
Output Btuh (kW) 36,900 (10.8) 49,200 (14.4) 61,700 (18.1)
�A.F.U.E. 80.1% 80.5% 80.1% 80.0%
California Seasonal Efficiency 75.4% 76.4% 75.9% 76.8% 76.8%
Flue size connection diameter � in. (mm) round 3 (76) 4 (102)
Temperature rise range � �F (�C) 30 - 60 (17 - 33) 45 - 75 (25 - 42)
High static certified by A.G.A./C.G.A. � in wg. (Pa) .50 (125)
Gas Piping Size I.P.S. Natural or LPG/propane 1/2 (13)
Blower wheel nominaldi t idth
in. 9 x 7 10 x 7 9 x 7 10 x 7Blower wheel nominal
diameter x widthmm 229 x 178 254 x 178 229 x 178 254 x 178
Blower motor output � hp (W) 1/4 (187) 1/3 (224) 1/4 (187) 1/3 (224)
Nominal coolingth t b dd d
Tons 1, 1-1/2 or 2 2, 2-1/2 or 3 1, 1-1/2 or 2 2, 2-1/2 or 3Nominal cooling
that can be addedkW 3.5, 5.3 or 7.0 7.0, 8.8 or 10.6 3.5, 5.3 or7.0 7.0, 8.8 or 10.6
Shipping weight � lbs. (kg) 1 package 130 (59) 135 (61)
Electrical characteristics 120 volts � 60 hertz � 1 phase (less than 12 amps) All models
� Optional Accessories (Must Be Ordered Extra) �
LPG/propane kit LB-69845L (38K84)
Twinning Kit 15L3801 � 5 lbs. (2 kg)
Up−Flow/Horizontal Filter and Filter Rack Kits�N & i f filt i ( )
Single (32J02) Ten Pack (66K64)Up Flow/Horizontal Filter and Filter Rack Kits�No. & size�of�filters�− in. (mm)
Single (32J02) Ten Pack (66K64)(1) 16 x 20 x 1 (406 x 508 x 25)
�Down-flowFilt Kit
Catalog No. LB-69843A (32J01) � 3 lbs. (1 kg)�Down flow
Filter KitNo. & Size of Filters � in. (mm) (2) 16 x 20 x 1 (406 x 508 x 25)
Down-flow Combustible Floor Base LB-79239A (67J91) � 10 lbs. (4 kg)
Sidewall Power Venting Kit 79J15 � 25 lbs. (11 kg)
Hanging Bracket Kit LB-69957 (46J66) � 15 lbs. (8 kg)
�Annual Fuel Utilization Efficiency based on U.S. DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherizedfurnaces.
�Polyurethane frame type filter is furnished with kit.�Filters are not furnished with kit and must be ordered extra.
Page 3
SPECIFICATIONS continuedModel No. 80MGF4(X)-75 80MGF3/4(X)-100 80MGF4/5(X)-100
Input Btuh (kW) 75,000 (22.0) 100,000 (29.3)
Output Btuh (kW) 61,700 (18.1) 82,000 (24.0)
�A.F.U.E. 80.0% 80.1% 80.0%
California Seasonal Efficiency 76.3% 76.5% 77.0%
Flue size connection diameter � in. (mm) round 4 (102)
Temperature rise range � �F (�C) 45 - 75 (25 - 42) 35 - 65 (19 - 36)
High static certified by A.G.A./C.G.A. � in wg. (Pa) .50 (125) .65 (162)
Gas Piping Size I.P.S. Natural or LPG/propane 1/2 (13)
Blower wheel nominaldi t idth
in. 12 x 8 12 x 9Blower wheel nominal
diameter x widthmm 305 x 203 305 x 229
Blower motor output � hp (W) 1/2 (373) 3/4 (560)
Nominal coolingth t b dd d
Tons 2, 2-1/2, 3, 3-1/2 or 4 3-1/2, 4, 5 or 6Nominal cooling
that can be addedkW 7.0, 8.8, 10.6, 12.3 or 14.1 12.3, 14.1, 17.6 or 21.1
Shipping weight � lbs. (kg) 1 package 140 (64) 175 (79)
Electrical characteristics 120 volts � 60 hertz � 1 phase (less than 12 amps) All models
� Optional Accessories (Must Be Ordered Extra) �
LPG/propane kit LB-69845L (38K84) LB-69845K (81J14)
Twinning Kit 15L3801 � 5 lbs. (2 kg)
Up−Flow/Horizontal Filter and Filter Rack Kits Single (32J02) Ten Pack (66K64) Single (46J14) Ten Pack (66K65)Up Flow/Horizontal Filter and Filter Rack Kits�No. & size�of�filters�− in. (mm)
Single (32J02) Ten Pack (66K64)(1) 16 x 20 x 1 (406 x 508 x 25)
Single (46J14) Ten Pack (66K65)(1) 20 x 20 x 1 (508 x 508 x 25)
�Down-flowCatalog No. LB-69843A (32J01) � 3 lbs. (1 kg)
�Down flowFilter Kit No. & Size of Filters � in. (mm) (2) 16 x 20 x 1 (406 x 508 x 25)
Down-flow Combustible floor Base LB-79239A (67J91) � 10 lbs. (4 kg) LB-79239B (67J92) � 10 lbs. (4 kg)
Sidewall Power Venting Kit 79J15 � 25 lbs. (11 kg)
Hanging Bracket Kit LB-69957 (46J66) � 15 lbs. (8 kg)
�Annual Fuel Utilization Efficiency based on U.S. DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherizedfurnaces.
�Polyurethane frame type filter is furnished with kit.�Filters are not furnished with kit and must be ordered extra.
Page 4
SPECIFICATIONS continued
Model No. 80MGF3/4-120 80MGF4/5(X)-120 80MGF4/5-140
Input Btuh (kW) 120,000 (35.2) 140,000 (41.0)
Output Btuh (kW) 98,400 (28.8) 114,800 (33.6)
�A.F.U.E. 80.0% 80.1% 80.0%
California Seasonal Efficiency Not Available 75.5% Not Available
�Flue size connection diameter � in. (mm) round 4 (102) 5 (127)
Temperature rise range � �F (�C) 45 - 75 (25 - 42)
High static certified by A.G.A./C.G.A. � in wg. (Pa) .50 (125) .65 (162)
Gas Piping Size I.P.S. Natural or LPG/propane in. (mm) 1/2 (13)
Blower wheel nominalin. 12 x 8 12 x 9
Blower wheel nominaldiameter x width mm 305 x 203 305 x 229
Blower motor output � hp (W) 1/2 (373) 3/4 (560)
Nominal coolingTons 2, 2-1/2, 3, 3-1/2 or 4 3-1/2, 4, 5 or 6
Nominal coolingthat can be added kW 7.0, 8.8, 10.6, 12.3 or 14.1 12.3, 14.1, 17.6 or 21.1
Shipping weight � lbs. (kg) 1 package 175 (79) 190 (86)
Electrical characteristics 120 volts � 60 hertz � 1 phase (less than 12 amps) All models
� Optional Accessories (Must Be Ordered Extra) �
LPG/propane kit LB-69845K (81J14)
Twinning Kit 15L3801 � 5 lbs. (2 kg)
Up−Flow/Horizontal Filter and Filter Rack Kits�No. & size�of�filters�− in. (mm
Single (46J14) Ten Pack (66K65)(1) 20 x 20 x 1 (508 x 508 x 25)
Single (58J93) Ten Pack (66K66)(1) 20 x 20 x 1 (508 x 508 x 25)
Catalog No. LB-69843A (32J01) � 3 lbs. (1 kg)
�Down-flowFilter Rack No. & Size
in. (2) 16 x 20 x 1Filter Rack No. & Size
of Filters mm (2) 406 x 508 x 25
Down-flow Combustible Floor Base LB-79239B (67J92) � 10 lbs. (4 kg) LB-79239C (67J93) � 12 lbs. (5 kg)
Sidewall Power Venting Kit 79J15 � 25 lbs. (11 kg)
Hanging Bracket Kit LB-69957 (46J66) � 15 lbs. (8 kg)
�Annual Fuel Utilization Efficiency based on U.S. DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized furnaces. �Polyurethane frame type filter is furnished with kit.�2 in. x 5 in. (51 mm x 127 mm) flue adaptor furnished with -140 input furnaces for connection to furnace induced draft blower.�Filters are not furnished with kit and must be ordered extra.
Page 5
BLOWER PERFORMANCE DATA
80MGF2-45, 80MGF2-60 AND 80MGF2-75 BLOWER PERFORMANCE
External Static Air Volume at Various Blower SpeedsExternal StaticPressure High Medium-High Medium-Low Low
in. w.g. Pa cfm L/s cfm L/s cfm L/s cfm L/s
0 0 1270 600 980 460 770 365 570 270
.05 12 1245 590 975 460 770 365 565 265
.10 25 1220 575 975 460 770 365 565 265
.15 37 1195 565 965 455 765 360 560 265
.20 50 1170 550 960 455 760 360 560 265
.25 62 1140 540 950 450 760 360 555 260
.30 75 1110 525 940 445 760 360 550 260
.40 100 1060 500 910 430 750 355 545 255
.50 125 990 465 880 415 740 350 540 255
.60 150 900 425 810 380 690 325 530 250
.70 175 800 380 740 350 630 295 520 245
NOTE � All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished) in place. Also see Filter Air Resistance table
80MGF3-60 AND 80MGF3-75 BLOWER PERFORMANCE
External Static Air Volume at Various Blower SpeedsExternal StaticPressure High Medium-High Medium-Low Low
in. w.g. Pa cfm L/s cfm L/s cfm L/s cfm L/s
0 0 1425 670 1240 585 1000 470 800 380
.05 12 1415 670 1230 580 995 470 800 380
.10 25 1400 660 1220 575 990 465 795 375
.15 37 1385 655 1200 565 985 465 795 375
.20 50 1370 645 1180 555 980 460 790 375
.25 62 1350 635 1160 545 970 460 780 370
.30 75 1330 630 1140 540 955 450 770 365
.40 100 1280 605 1095 515 925 435 750 355
.50 125 1210 570 1040 490 900 425 720 340
.60 150 1135 535 985 465 860 405 680 320
.70 175 1070 505 920 435 800 380 630 300
NOTE � All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished) in place. Also see Filter Air Resistance table
Page 6
80MGF4-75, 80MGF3/4-100 AND 80MGF3/4-120 BLOWER PERFORMANCE
External StaticAir Volume at Various Blower Speeds
External StaticPressure High Medium-High Medium Medium-Low Low
in. w.g. Pa cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s
0 0 1830 865 1600 755 1325 625 1070 505 880 415
.05 12 1815 855 1585 750 1320 625 1070 505 880 415
.10 25 1800 850 1570 740 1315 620 1070 505 880 415
.15 37 1875 885 1550 730 1310 620 1065 505 875 415
.20 50 1750 825 1530 720 1300 615 1060 500 875 415
.25 62 1725 815 1515 715 1290 610 1050 495 870 410
.30 75 1700 800 1500 710 1275 600 1040 490 870 410
.40 100 1650 780 1460 690 1245 590 1020 480 860 405
.50 125 1600 755 1420 670 1210 570 1000 470 840 395
.60 150 1550 730 1380 650 1170 550 980 460 820 385
.70 175 1480 700 1330 630 1130 535 960 455 790 375
NOTE � All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished) in place. Also see Filter Air Resistance table
80MGF4/5-100, 80MGF4/5-120 AND 80MGF4/5-140 BLOWER PERFORMANCE
External StaticAir Volume at Various Blower Speeds
External StaticPressure High Medium-High Medium Medium-Low Low
in. w.g. Pa cfm L/s cfm L/s cfm L/s cfm L/s cfm L/s
0 0 2450 1155 2160 1020 1970 930 1700 800 1500 710
.05 12 2440 1150 2155 1015 1965 925 1695 800 1500 710
.10 25 2430 1145 2150 1015 1960 925 1690 800 1495 705
.15 37 2415 1140 2135 1010 1950 920 1685 795 1495 705
.20 50 2400 1135 2120 1000 1940 915 1680 795 1490 705
.25 62 2380 1125 2105 995 1930 910 1675 790 1480 700
.30 75 2360 1115 2090 985 1915 905 1670 790 1470 695
.40 100 2310 1090 2050 965 1870 880 1650 780 1440 680
.50 125 2260 1065 2000 945 1810 855 1610 760 1410 665
.60 150 2180 1030 1950 920 1750 825 1560 735 1370 645
.70 175 2100 990 1890 890 1700 800 1520 715 1330 630
NOTE � All air data is measured external to unit with 1 in. (25 mm) cleanable filter (not furnished) in place. Also see Filter Air Resistance table
FILTER AIR RESISTANCE
cfm (L/s) in. w.g. (Pa)
0 (0) 0.00 (0)
200 (95) 0.01 (2)
400 (185) 0.03 (7)
600 (280) 0.04 (10)
800 (375) 0.06 (15)
1000 (470) 0.09 (22)
1200 (560) 0.12 (30)
1400 (655) 0.15 (37)
1600 (750) 0.19 (47)
1800 (845) 0.23 (57)
2000 (935) 0.27 (67)
2200 (1030) 0.33 (82)
2400 (1125) 0.38 (95)
2600 (1220) 0.44 (110)
Page 7
FIGURE 1
80MGF PARTS IDENTIFICATIONand ORIENTATION VENT ADAPTER
CABINET TOP
80MGFCABINET
CABINETBOTTOM
HEAT EXCHANGERASSEMBLY
BURNERASSEMBLY
BLOWER ASSEMBLY
COMBUSTION AIRBLOWER
FLUE BOX
SECONDARYLIMITS
FRONT ACCESSPANEL
DOOR INTERLOCK SWITCH
CONTROLBOARD
TRANSFORMER
PRESSURESWITCH
NOxTURBULATOR
PRIMARYLIMIT
FIGURE 2
HEATING COMPONENTS (shown in horizontal position)
HEAT EXCHANGER
COMBUSTION AIR BLOWER
MANIFOLD
ROLLOUT SWITCH (2)
COMBUSTION AIRPROVE SWITCH
GAS VALVE
BURNERS
COLLECTOR
PRIMARY LIMIT
Front
Right
Top
Bottom
Left
Back
Page 8
FIGURE 3
Top
80MGF BURNER ASSEMBLY (Shown With SureLight ignitor)
FLAMESENSOR
MANIFOLD
ORIFICE
GAS VALVE
HEAT EXCHANGER
VEST PANEL
BURNER
UPPERBURNER
MOUNTINGRAIL
LOWERBURNER
MOUNTINGRAIL
BURNER BOX
BURNER BOXTOP
FrontRight
Bottom
LeftBack
PRIMARY LIMIT
ROLLOUTSWITCHES
SURELIGHT IGNITOR
FIGURE 4
80MGF BLOWER DOOR COMPONENTS − BLOWER ACCESS(SureLight MODEL SHOWN)
1
5
8
To Access Blower:
1− Turn off power to unit and disconnect L1 and L2line voltage power.
2− Disconnect thermostat wiring connectionsfrom furnace control board.
3− Disconnect blower leads from control board.
4− Disconnect J1 from P1.
5− Disconnect 6 pin P156 from control board.
6− Disconnect 9 pin P58 from control board.
7− Disconnect sensor wiire from center of board.
8− Remove screws (2) and lift panel from unit.
2
Top
Bottom
Left
Right
Front
3
4
6
Back
7
Page 9
I−UNIT COMPONENTS (Figures 1, 2, 3)
80MGF unit components are shown in figure 1. The blower
controls, gas valve and burners can be accessed by re-
moving the front access panel. A separate blower access
door is located behind the front access panel. Electrical
control components are mounted to the blower access
door.
80MGF units are factory equipped with bottom return air pan-
els. The panels are designed to be field removed as required
for bottom air return. Indentations on side of units, show
where side air return opening should be cut during installation.
A−Blower Door Components (Figure 4)Electrical burner control and blower control components
are located on the outside surface of the blower access
door. Jackplugs allow the blower door to be easily re-
moved for blower service.
Located on the blower door are the unit transformer (T1),
the furnace control (A3) and door interlock switch (S51).
Furnace control (A3) combines the function of a burner
ignition control and blower control.
1− Control Transformer (T1)
A transformer located on the blower door provides power
to the low voltage section of the unit. Transformers on all
models are rated 30VA with a 120V primary and a 24V sec-
ondary.
2−Door Interlock Switch (S51)
A door interlock switch rated 16A at 125VAC is located on
the blower access door. The switch is wired in series with
line voltage. When the blower door is removed the unit will
shut down.
3− Ram Control (A3)The furnace control combines burner ignition functions
with blower control functions.
Some early model 80MGF units utilize a furnace control
manufactured by RAM Electronics Corporation. The �RAM"
board is a printed circuit board which controls the blower, gas
valve, combustion air blower and ignition spark. It also moni-
tors the flame, limit and gas valve operation. The control has
a non−adjustable, factory preset �on" fan timing (45 sec-
onds). Fan �off" timings are adjustable. The board utilizes
both 120 and 24VAC. See figure 5. The board is also
equipped with a diagnostic LED for use when troubleshoot-
ing the unit.
When the furnace is idle (blower off and no heating or cool-
ing demand), the diagnostic LED flashes at a slow steady
rate. On a call for heat, the diagnostic LED begins flashing
at a fast rate and the combustion air blower is energized.
The LED flashes different codes to indicate problem con-
ditions. The diagnostic LED lights red (not flashing) to indi-
cate control board failure. Table 3 shows how to interpret the
other LED modes.
Pre-Purge
On a call for heat, the combustion air blower begins oper-
ating. If the combustion air prove switch closes, the com-
bustion air blower continues to operate for 45 seconds
(pre-purge) before allowing ignition. Pre-purge allows the
heat exchanger to be cleared of combustion products and
to introduce fresh air for combustion. If the combustion air
prove switch does not close, the combustion air blower
continues to run indefinitely (until the prove switch closes).
Post-Purge
After a demand, the combustion air blower continues to
operate for 5 seconds (post-purge) before stopping. Post-
purge allows the heat exchanger to be cleared of combus-
tion products.
Ignition Control
The ignition control is a direct spark ignition control module
integral to the furnace control. See figure 5. When there is a
call for heat, the control delays ignition until combustion air
blower operation has been proved and pre-purge period
has elapsed. It then opens the gas valve and generates a
spark to ignite the burners. Trial for ignition lasts for 7 sec-
onds. At the same time, the control begins monitoring the
flame sensor. If the flame current is too weak (less than 1
microamp) or if the burners do not ignite (within the 7 sec-
ond ignition trial), the control will shut off spark and the com-
bustion air blower and de-energize the gas valve. Flame
current should be between 1 and 5 microamps to keep the
gas valve open. See figure 23.
The control will attempt to ignite the burners up to two more
times. Each time the control restarts the ignition sequence,
it begins with a 45 second pre-purge. If flame is not sensed
after the third trial, the control locks out. Lockout means that
the control shuts off the gas valve, spark and combustion air
blower for 60 minutes. At the end of 60 minutes the control
completely resets and will attempt ignition up to three times.
The control can be manually reset before the end of 60 min-
utes by momentarily turning off power to the unit.
DANGERShock hazard.
Spark related components contain high voltage.Disconnect power before servicing. Control isnot field repairable. If control is inoperable, sim-ply replace entire control.
Can cause injury or death. Unsafe operation willresult if repair is attempted.
Page 10
RAM CONTROL (A3)
FIGURE 5
LINE VOLTAGETERMINAL
CONNECTIONS
24VAC VOLTTERMINAL
CONNECTIONS
THERMOSTATCONNECTIONS
DIAGNOSTICLED
See Table 2 forTerminal Func-
tions
See Table 2 forTerminal Func-
tions
FAN-OFF TIMINGSWITCHES
SPARK OUTPUT
TABLE 1
Furnace Control A3 Limit Response During Operation
Response
ConditionCombustion
AirBlower
GasValve
SupplyAir
Blower
DiagnosticLED
Loss of FlameSensed BeforeEnd of 45 sec-ond Blower On
Delay(3 or Fewer
Trialsfor Ignition)
On
On(SparkStarts
Within 0.8seconds)
On Fast Flash
Loss of FlameSensed After
45 secondBlower OnDelay (3 or
Fewer Trialsfor Ignition)
On
Off ThenOn WithSpark
After Pre-Purge
On Fast Flash
Loss of FlameSensed (MoreThan 3 Trialsfor Ignition)
Off Off Off 2 Flashes
Flame SensedWithoutDemand
On Off On 5 Flashes
Primary or Sec-ondary Limit
OpenOn Off On 4 Flashes
Rollout SwitchOpen
On Off On 4 Flashes
Combustion AirProve Switch
OpenOn Off On 3 Flashes
When flame is sensed, the indoor blower starts after a 45
second delay. Gas valve remains open and blower contin-
ues to run until demand stops, flame sensor senses loss of
flame, a limit opens or the prove switch opens. If any of
these events occur during a thermostat demand, the gas
valve closes and the diagnostic LED registers the error
condition (table 1).
Blower Control and Timings
DANGERElectrical Shock Hazard.This control contains field adjustable switchesand also contains line voltage. Make sure poweris disconnected before making any field adjust-ments or performing any service procedure.
NOTE�If fan �off" time is set too low, residual heat in
heat exchanger may cause primary limit S10 to trip re-
sulting in frequent cycling of blower. If this occurs, ad-
just blower to longer time setting.
Fan �ON" timing (time that the burners operate before the
supply air blower starts) is fixed at 45 seconds and cannot
be adjusted.
Page 11
Fan �OFF" timings (time that the blower operates after a
heating or cooling demand has been satisfied) are de-
termined by the arrangement of switches on the furnace
control board. See figure 5. To adjust fan �off " timings,
gently reposition the switches to a new timing position.
Figure 6 shows the various fan �off" timings and how
switches should be positioned. 80MGF−1, −2, −3, −4 and −6
units are shipped with a factory fan �off" setting of 180 sec-
onds. 80MGF−5 and −7 units are shipped with factory "off"
setting of 60 seconds. Fan �off" time will affect comfort and
efficiency and is adjustable to satisfy individual applica-
tions. The fan �off" timing is initiated after a heating or cool-
ing demand but not after a blower demand (that is, when
indoor thermostat switch is changed from ON to AUTO
and heating/cooling demand is not present, the blower
stops immediately).
TABLE 2
FURNACE CONTROL A3 TERMINAL DESIGNATIONS
Terminal Type Function
Y Screw Strip Cooling Demand
G Screw Strip Blower Demand
R Screw Strip 24VAC to Thermostat
W Screw Strip Heating Demand
C
Early Units1/4" Spade
24VAC CommonCLater UnitsScrew Strip
24VAC Common
120VAC HOT 1/4" Spade Line Voltage In
AUX 1/4" Spade Line Voltage Out (Switched)
CMB BLWR 1/4" SpadeSwitched 120VAC to
Combustion Air Blower
ACB HEAT 1/4" SpadeSwitched 120VAC toBlower Heating Tap
ACB COOL 1/4" SpadeSwitched 120VAC to Blower
Cooling Tap
VALVE 1/4" Spade 24VAC to Gas Valve
24VAC HOT 1/4" Spade 24VAC In From Transformer
GROUND 1/4" Spade To Cabinet Ground
FLAME SENSE 1/4" Spade Flame Microamp Sensing
PSW 1/4" Spade24VAC In From Pressure SwitchSwitch Open: Prohibits IgnitionSwitch Closed: Allows Ignition
HI LIMIT IN 1/4" Spade24VAC In From Limits
Limit Open: Closes Gas ValveLimits Closed: Allows Ignition
HI LIMIT OUT 1/4" Spade24VAC to Limit Trainand Pressure Switch
ROLLOUT IN 1/4" Spade 24VAC In From Rollout Switches
FIGURE 6
FAN-OFF TIME ADJUSTMENT SWITCHESLOCATED ON FURNACE CONTROL (A3)
Fan-Off Timings
Switch
1 2
TimingSeconds
Off
OnOff
Off
OffOn
On On
120
90
180
240
Diagnostic LED
The furnace control is equipped with a diagnostic LEDused for troubleshooting the unit and the control. LEDfunctions are shown in table 3.
TABLE 3
Furnace Control A3 Diagnostic LED
LED State Meaning Remedy
Steady On Control Failure Replace Control
Slow FlashNormal Operation and
No Call For Heat- - - -
Fast FlashNormal Operation with
Call For Heat- - - -
TwoFlashes
Control Lockout
Failed to Sense or SustainFlame. Check Gas Valve,Burners, Spark Electrodeand Wire, Flame Sensor.Replace Control If All OK.
ThreeFlashes
Pressure Switch Open
Failed to Prove Combus-tion Blower Operation orBlocked Vent. Repair orReplace as Necessary.
FourFlashes
Open Limit
Check Primary Limit, RolloutSwitches and Secondary
Limits. Find source of Over-temperature. If all OK, Resetor Replace Limits as Neces-
sary.
FiveFlashes
Flame Sensed and GasValve Not Energized.
Check Gas Valve. If OK,Check Flame Sensor.
Page 12
4− EGC Control (A3)Some early model 80MGF units are equipped with an inte-
grated ignition/blower control (EGC−1 or EGC−2) which con-
trols ignition, safety circuits, blower operation, fan off timing,
and allows for thermostat connection and troubleshoot-
ing. The EGC is a printed circuit board which is divided
into two sections, 120 and 24VAC. Line voltage comes
into the board on the 120VAC side. See figure 8. Terminal
designations are listed in tables 5 and 6.
Ignition Control
80MGF units use the EGC direct spark integrated igni-
tion control. The EGC controls and monitors the entire
sequence of operation. On a call for heat from the ther-
mostat the control monitors the combustion air blower
pressure switch. The control will not begin the heating
cycle if the pressure switch is closed (by-passed). Once
the pressure switch is determined to be open, the combus-
tion air blower is energized. When the differential in pres-
sure across the pressure switch is great enough, the pres-
sure switch closes and a 15 second pre-purge period
begins. After the pre-purge period, the gas valve will open
and ignition (spark) will be attempted for 10 seconds. After
ignition, the control initiates a ten second flame stabiliza-
tion period. The flame stabilization period allows the
burners to heat up and the flame to stabilize. Once flame
is established, the control will constantly monitor the burner
flame using flame rectification. Flame failure response time is
0.8 seconds.
If the initial attempt for ignition fails, the sequence is re-
peated up to five times. After the fifth trial, the control goes into
�Watchguard"*. During watchguard mode, the entire unit will
be de-energized for one hour. After one hour the control will
repeat the ignition sequence. Watchguard may be manually
reset by breaking and remaking thermostat demand.
*NOTE−If flame is established beyond the 10 second flame
stabilization period then lost, the control resets for five more
ignition trials. The control can be reset five times during one
unsatisfied thermostat demand, providing a maximum
of 25 trials for ignition.
Safety Circuits
During the entire heating demand the control monitors the
safety circuits. If the primary or secondary heating limits
open, the control de-energizes the main gas valve and
combustion air blower while the indoor blower remains en-
ergized. When the limit automatically resets, the ignition se-
quence also resets. If either of the limits trip five consecu-
tive times during one unsatisfied thermostat demand, the
control will go into watchguard for one hour.
The control monitors main valve voltage. If voltage is sensed
when no voltage should be present, the control de-energizes
the combustion air blower which terminates voltage to the
valve. The system goes into hard lock-out which is reset only
by removing power to the unit.
If flame is sensed when no flame should be present, the con-
trol will energize the combustion and indoor blowers. The
unit will remain locked in this sequence until the flame is no
longer sensed or the main power is turned off to reset the
control.
DANGERShock hazard. Avoid personal injury. Make sure todisconnect power before changing fan �off" timing.
Blower Operation / Fan Off Timings
Fan �off" timing (time that the blower operates after the heat
demand has been satisfied) can be adjusted by moving the
jumper on the EGC blower control board. Figure 7 shows
the various fan �off" timings and how jumper should be posi-
tioned. To adjust fan �off " timing, gently disconnect jumper
and reposition across pins corresponding with new timing.
Unit is shipped with a factory fan �off" setting of 180 seconds.
Fan �on" time is factory set at 45 seconds following the
opening of the main gas valve and is not adjustable.
Fan �off" time will affect comfort and efficiency and is ad-
justable to satisfy individual applications. The fan �off" tim-
ing is initiated after a heating demand but not after a cool-
ing demand.
NOTE�If fan �off" time is set too low, residual heat in
heat exchanger may cause primary limit S10 to trip, re-
sulting in frequent cycling of blower. If this occurs, adjust
blower to longer fan �off" time setting.
FIGURE 7
FAN-OFF TIME ADJUSTMENT
180 60
120 90
To adjust fan-off timing:Remove jumper from EGC and select oneof the other pin combinations to achieve
the desired time.
TIMINGJUMPER
TIMING PINS(seconds)
Leave jumper off for240 second fan-off timing.
Thermostat Connection
Thermostat wires are connected to the terminal strip
found on the EGC control board.
Page 13
Troubleshooting
The EGC control board is equipped with two diagnostic green
LEDs to indicate the mode of failure. The LED lights are
marked DIAG #1 and DIAG #2. The codes are given in table
4. On the EGC−1 only, the last failure code is stored in
memory and may be retrieved by depressing and holding
the memory recall button. When this button is depressed,
the LEDs will signal the last failure code in memory. Power
must be restored to the control (depress blower interlock
switch) within one minute of blower access panel removal in
order to retain memory. To clear the memory of the stored
failure code, remove main power and short the jumper next
to the diagnostic button for five seconds.
TABLE 4
EGC DIAGNOSTIC CODES
DIAG #2 DIAG #1 DIagnostic Condition
SimultaneousFlash
SimultaneousFlash
Power �ON". Normal Operation. In-creased flash rate indicates there
is a heating demand.
On FlashPrimary or Secondary
Limit Switch Open.Auto-Reset Switch.
Flash Off
Pressure Switch Watchguard,pressure switch opened during
operation or condensatedrain blocked.
AlternateFlash Alternate Flash
Watchguard, burnersfailed to ignite.
Off FlashFlame sensed without
valve energized.
Flash OnRoll-out Switch Open.Manual-Reset Switch.
ContinuousOn Continuous On
Circuit board self-check failure orignition/blower controlis wired incorrectly.
FIGURE 8
EDGECONNECTION
THERMOSTATTERMINAL STRIP(DETACHABLE)
BLOWER TIMEADJUSTMENT
JUMPER
DIAGNOSTIC MODULE
DIAGNOSTIC LEDS
RED DIAGNOSTIC BUTTON(EGC−1 only. Depress button and hold
for display of last failure code.)
DIAGNOSTIC CODE ERASE JUMPER(Remove power to control and short pins for
10 seconds to erase previous code.)
24VACPLUG P20
5
6
7
8 9 10 11 12 13 15
123
4
14 16
1
2
3
4
6
5
7
8
9
EGC−2 INTEGRATED CON-TROL
NOTE: EGC−1 board will have terminal (#15) forACB low speed.
*
*
**
** NOTE: EGC−1 board will have terminal(#16) for ACB Heat speed.
Page 14
TABLE 5BLOWER CONTROL A15 TERMINAL DESIGNATIONS
TerminalDesignation(See fig. 8)
Type Function
R Screw Strip 24VAC to Thermostat (Red)
G Screw StripManual Fan Input from Thermostat
(Green)
W Screw StripHeat Demand Input from Thermostat
(White)
Y Screw StripCool Demand Input from Thermostat
(Yellow)
C Screw Strip Common Ground to Thermostat
1 1/4" Spade 24VAC Hot from Transformer
2 1/4" Spade 24VAC Return to Transformer
3 1/4" Spade 24VAC Ground
4, 5, 6 1/4" Spade 120VAC Return − 120VAC Common
7 1/4" Spade120VAC Return − 120VAC Common
Input
8 1/4" Spade Combustion Blower (Line Voltage)
9 1/4" Spade Heat Only Accessory (Line Voltage)
10 1/4" Spade 120VAC Hot to Transformer
11 1/4" Spade 120VAC Hot Input
12, 13 1/4" Spade Accessories (Line Voltage)
14 1/4" Spade ACB Cool Speed (Line Voltage)
15 1/4" Spade
EGC−1 ACB Low Cont. Speed (Line Voltage)
EGC−2 ACB Heat Speed (Line Voltage)
16 1/4" Spade ACB Heat Speed (Line Voltage)
TABLE 6
EGC CONTROL JACK/PLUG 20 TERMINAL DESIGNATIONS
Pin # Function
1 Rollout Switch Out
2 Spare
3 Gas Valve Common
4 Pressure Switch Return
5 Hi Limit Return / Pressure Switch Out
6 Flame Sensor
7 Gas Valve Out
8 High Limit Out
9 Rollout Switch Return
DANGERShock hazard.
Disconnect power before servicing. Control is notfield repairable. If control is inoperable, simplyreplace entire control.
Can cause injury or death. Unsafe operation willresult if repair is attempted.
5−Flame Sensor (−11 models)A flame sensor is located on the left side of the burner sup-
port. See figure 9. The sensor is mounted on a bracket in
the burner support and the tip protrudes into the flame en-
velope of the left−most burner. The sensor is fastened to
burner supports and can be removed for service without
removing any part of the burners. During operation, flame
is sensed by current passed through the flame and sens-
ing electrode. The SureLight control allows the gas valve
to remain open as long as flame signal is sensed.
FIGURE 9
NORMAL FLAME SIGNAL � 0.7 MICROAMPSLOW FLAME SIGNAL � 0.7 MICROAMPSMINIMUM FLAME SIGNAL � 0.15 MICROAMPS
BURNER
FLAMESENSORSIDE VIEW END VIEW
1/4 in. 7 mm� 1/32 in. 0.79
mm
3/16 in.4.7 mm
11/16 in. 18 mm� 1/32 in. 0.79
mm
NOTE − The 80MGF furnace contains electronic com-
ponents that are polarity sensitive. Make sure that the
furnace is wired correctly and is properly grounded.
6− SureLight Ignition System A3 (−11 models)
All 80MGF−11 model units are equipped with the LennoxSureLight ignition system. The system consists of ignitioncontrol board (figure 11 with control terminal designa-tions in table 10) and ignitor (figure 12). The board and ig-nitor work in combination to ensure furnace ignition andignitor durability. The SureLight integrated board controlsall major furnace operations. The board also features twoLED lights for troubleshooting and two accessory termi-nals rated at (4) four amps. See table 9 for troubleshoot-ing diagnostic codes. Table 7 and 8 show jack plug termi-nal designations. Units equipped with the SureLightboard can be used with either electronic or electro−me-chanical thermostats without modification. The SureLightignitor is made of durable silicon−nitride. Ignitor longevityis also enhanced by voltage ramping by the control board.The board finds the lowest ignitor temperature which willsuccessfully light the burner, thus increasing the life of theignitor.
Page 15
TABLE 7
SureLight BOARD J156 (J2) TERMINAL DESIGNATIONS
PIN # FUNCTION
1 Ignitor
2 Not Used
3 Ignitor Neutral
4 Combustion Air Blower Line Voltage
5 Not Used
6 Combustion Air Blower Neutral
TABLE 8
SureLight BOARD J58 (J1) TERMINAL DESIGNATIONS
PIN # FUNCTION
1 Primary Limit In
2 Gas Valve Common
3 Roll Out Switch Out
4 Gas Valve 24V
5 Pressure Switch In
6 Pressure Switch and Primary Limit Out
7 Not Used
8 Roll Out Switch In
9 Ground
CAUTIONElectrostatic discharge can affect electroniccomponents. Take precautions during furnaceinstallation and service to protect the furnace’selectronic controls. Precautions will help to avoidcontrol exposure to electrostatic discharge byputting the furnace, the control and the techni-cian at the same electrostatic potential. Neutral-ize electrostatic charge by touching hand and alltools on an unpainted unit surface, such as thegas valve or blower deck, before performing anyservice procedure.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
a−Electronic IgnitionOn a call for heat the SureLight control monitors the com-
bustion air blower pressure switch. The control will not be-
gin the heating cycle if the pressure switch is closed (by−
passed). Once the pressure switch is determined to be
open, the combustion air blower is energized. When the
differential in the pressure switch is great enough, the
pressure switch closes and a 15−second pre−purge be-
gins. If the pressure switch is not proven within 2−1/2 min-
utes, the control goes into Watchguard−Pressure Switch
mode for a 5−minute re−set period.
After the 15−second pre−purge period, the SureLight igni-
tor warms up for 20 seconds after which the gas valve
opens for a 4−second trial for ignition. 80MGF units with
board 63K89, 24L85 or 56L83: the ignitor stays energized
for the first second of the 4−second trial. Units with board
97L48: ignitor stays energized for the full 4−second trial for
ignition. If ignition is not proved during the 4−second peri-
od, the control will try four more times with an inter purge
and warm−up time between trials of 35 seconds. After a to-
tal of five trials for ignition (including the initial trial), the
control goes into Watchguard−Flame Failure mode. After a
60−minute reset period, the control will begin the ignition
sequence again.
The SureLight control board has an added feature that
prolongs the life of the ignitor. After a successful ignition,
the SureLight control utilizes less power to energize the ig-
nitor on successive calls for heat. The control continues to
ramp down the voltage to the ignitor until it finds the lowest
amount of power that will provide a successful ignition.
This amount of power is used for 255 cycles. On the 256th
call for heat, the control will again ramp down until the low-
est power is determined and the cycle begins again.
b−Fan Time Control
The fan on time of 45 seconds is not adjustable. Fan off
time (time that the blower operates after the heat demand
has been satisfied) can be adjusted by flipping the dip
switches located on the SureLight integrated control. The
unit is shipped with a factory fan off setting of 90 seconds.
Fan off time will affect comfort and is adjustable to satisfy
individual applications. See figure 10.
FIGURE 10
FAN-OFF TIME ADJUSTMENT
To adjust fan−off timing, flip dip switch to desired setting.
60sec. 90sec. 120sec. 180sec.
Page 16
The SureLight board is equipped with two LED lights for troubleshooting. The lights are found just above the 24VAC termi-
nal strip see figure 8. The diagnostic codes are listed below in table 9.
TABLE 9 DIAGNOSTIC CODES
MAKE SURE TO ID LED’S CORRECTLY: REFER TO INSTALLATION INSTRUCTIONS FOR CONTROL BOARD LAYOUT.
LED #1 LED #2 DESCRIPTION
SIMULTANEOUSSLOW FLASH
SIMULTANEOUSSLOW FLASH
Power − Normal operationAlso signaled during cooling and continues fan.
SIMULTANEOUS FASTFLASH
SIMULTANEOUS FASTFLASH
Normal operation − signaled when heating demand initiated at thermostat.
SLOW FLASH ON
Primary or Secondary limit open. Units with board 63K8901 or 24L85: Limit mustclose within 5 trials for ignition or board goes into one hour limit Watchguard.Units with board 56L83 or 97L48: Limit must close within 3 minutes or board
goes into one hour limit Watchguard.
OFF SLOW FLASH
Pressure switch open or has opened 5 times during a single call for heat; OR:Blocked inlet/exhaust vent; OR: Condensate line blocked; OR: Pressure switch
closed prior to activation of combustion air blower.
ALTERNATING SLOWFLASH
ALTERNATING SLOWFLASH
Watchguard − burners fail to ignite.
SLOW FLASH OFF Flame sensed without gas valve energized.
ON SLOW FLASH Rollout switch open. OR: 9 pin connector improperly attached.
ONONOFF
ONOFFON
Circuit board failure or control wired incorrectly.
FAST FLASH SLOW FLASH Main power polarity reversed. Switch line and neutral.
SLOW FLASH FAST FLASH Low flame signal. Measures below .7 microAmps. Replace flame sense rod.
ALTERNATING FASTFLASH
ALTERNATING FASTFLASH
Improper main ground or line voltage below 75 volts; OR: Broken ignitor; OR:Open ignitor circuit.
NOTE − Slow flash equals 1 Hz (one flash per second). Fast flash equals 3 Hz (three flashes per second). Drop out flame sense current < 0.15 microAmps
SURELIGHT INTEGRATED CONTROL BOARD
FIGURE 11
FIGURE 12
SURELIGHT IGNITOR
SureLight Ignitor
TABLE 10
TERMINAL DESIGNATIONS
ACB COOL
ACB HEAT
PARK
ACB LOW
ACC
TX
HOT
HTG ACC
NEUTRALS
24VAC HOT
24VAC RTN
FLAME SENSE
Blower − Cooling Speed (Line Volt)
Blower − Heating Speed (Line Volt)
Alternate Blower Speeds (Dead)
Continuous Low Speed Blower
Accessory Terminal (Line Volt)
120VAC Hot to Transformer
120VAC Hot Input
Heat Only Accessory (Line Volt)
120VAC Neutrals
24VAC Hot from Transformer
24VAC Return from Transformer
Flame Sense Terminal
Page 17
B−Blower Motors and Capacitors
All 80MGF units use direct drive blower motors. All motors
used are 120V permanent split capacitor motors to ensure
maximum efficiency. See table 11 for ratings.
TABLE 1180MGF BLOWER RATINGS 120V 1PH
BLOWER MOTOR HP
80MGF2
80MGF3
80MGF3/4
CAP
1/2
1/3
1/4 5MFD 370V
5MFD 370V
7.5MFD 370V
80MGF5/6
80MGF4
80MGF4/5
1/2 7.5MFD 370V
3/4 40MFD 370V
3/4 40MFD 370V
FrontBottom
Right
Left
TopBack
FIGURE 13
SUPPLY AIR BLOWERAND SECONDARY LIMITS
BLOWERMOTOR
To Remove Blower From Unit: Remove Bolts andWiring Jackplugs. Then Slide Out Front of Unit.
MOTORCAPACITOR
SECONDARYLIMITS (S21)
C−Combustion Air Blower (B6)All 80MGF units use a combustion air blower to move air
through the burners and heat exchanger during heating
operation. The blowers will use either a shaded pole 120V
motor or a C−frame 120V motor. Shaded pole and C−frame
motors do not use run capacitors. The motor operates dur-
ing all heating operation and is controlled by furnace con-
trol A3. The motor also operates for a period before burner
ignition (pre−purge). The pre−purge time is 45 seconds for
80MGF units equipped with the RAM control and 15 sec-
onds for units equipped with the EGC control. With either
the RAM, EGC or SureLight control board, the motor will
operate 5 seconds after the gas valve closes (post-purge).
A pressure switch connected to the combustion air blower
housing is used to prove combustion air blower operation.
The switch monitors air pressure in the blower housing. Dur-
ing normal operation, the pressure in the housing is nega-
tive. If pressure becomes less negative (signifying an ob-
struction) the pressure switch opens. When the pressure
switch opens, the furnace control (A3) immediately closes
the gas valve to prevent burner operation.
D−Flame Rollout Switches (S47)Flame rollout switch is a high temperature limit located on
top of the burner box. Each furnace is equipped with two
identical switches. One switch is located over the leftmost
burner and the other switch is located over the rightmost
burner. The limit is a N.C. SPST manual-reset limit con-
nected in series with the ignition control A3. When S47
senses rollout, the ignition control immediately stops igni-
tion and closes the gas valve. If unit is running and flame
rollout is detected, the gas valve will close and ignition con-
trol will be disabled. Rollout can be caused by a blocked
flue or lack of combustion air. The switch is factory set and
cannot be adjusted. The setpoint will be printed on the side of
the limit. The switch can be manually reset. To manually re-
set a tripped switch, push the reset button located on the
control.
FIGURE 14
ROLLOUT SWITCH (S47)
MANUALRESET BUTTON
E−Primary Limit Control (S10)
FIGURE 15
80MGF SERIES UNITSLIMIT CONTROL FOR
THIS TYPE AUTO-RESET LIMITIS USED FOR THE PRIMARY LIMIT (S10) AND
RIGHT SECONDARY LIMIT (S21)(see FIGURE 13)
The primary limit (S10) on 80MGF units is located in the
middle of the heating vestibule panel. When excess heat is
sensed in the heat exchanger, the limit will open. If the limit is
tripped, the furnace control energizes the supply air blower
and closes the gas valve. The limit automatically resets when
unit temperature returns to normal. The switch is factory set
and cannot be adjusted. The switch may have a different
setpoint for each unit model number. However, the setpoint
will be printed on the side of the limit. There are two types of
primary limit. See figures 15 and 16.
Page 18
F−Secondary Limit Controls (S21)The secondary limit (S21) on 80MGF units is located in the
blower compartment in the back side of the blower housing.
When excess heat is sensed in the heat blower compartment,
the limit will open. If the limit is tripped, the furnace control en-
ergizes the supply air blower and closes the gas valve. The
limit automatically resets when unit temperature returns to
normal. The switch is factory set and cannot be adjusted.
Two limits are supplied in each furnace and each limit is a
different style (figures 15 and 16). The setpoint will be
printed on the side of the limit. If stick limit (Figure 16) suf-
fers from nuisance trips and the furnace is in the horizontal
position, replace with limit kit no. 50L98.
INSULATING COVER (s)
FIGURE 16
LIMIT CONTROL (S21) (S10)FOR 80MGF SERIES UNITS
SPAD
E C
ON
NE
CT
OR
S
INSU
LA
TIN
G C
OV
ER L
IMIT
LIM
IT
THIS TYPE AUTO-RESET LIMIT ISUSED FOR THE LEFT SECONDARY
LIMIT (S21) (see FIGURE 13)
G−Spark Electrode and Flame Sensor(Models with EGC or Ram control only)
Figure 17 shows the arrangement of flame sensor, spark
electrode and burners. The Ram and EGC ignition control
uses direct spark to ignite the rightmost burner and the
burners cross-light to the left. The flame sensor uses flame
rectification to sense combustion. A flame retention ring in
the end of each burner is used to maintain correct flame
length and shape and to keep the flame from lifting off the
burner head.
Figure 18 shows the gap between tip of the electrodes and
the burner surface.
H−Gas ValveThe 80MGF uses a gas valve manufactured by Honey-
well or WhiteRodgers. The valve is internally redundant to
assure safety shut−off. If the gas valve must be replaced,
the same type valve must be used.
24VAC terminals and gas control knob are located on top of
the valve. All terminals on the gas valve are connected to
wires from the electronic ignition control. 24V applied to the
terminals energizes the valve.
Inlet and outlet pressure taps are located on the valve. A regu-
lator adjustment screw is located on the valve. Refer to figures
19 or 20 for location of valve features.
An LPG changeover kit is available from Lennox. The kit in-
cludes burner orifices and a regulator conversion kit.
FIGURE 17
TYPICAL BURNER/ELECTRODE ORIENTATIONDIRECT SPARK MODELS ONLY
BURNER
FLAME RETENTION RING
UPPER BURNERMOUNTING RAIL
LOWER BURNERMOUNTING RAIL
MANIFOLD ORIFICE
Right Left
Top
Bottom
FLAME SENSORSPARK ELECTRODE GROUND
1/8"(+1/64")
23/32 in.(18 mm)
Page 19
FIGURE 18
SPARK ELECTRODE TO BURNER GAP
SPARK ELECTRODE
BURNER
FLAME SENSOR TO BURNER GAPBURNER
FLAME SENSOR
SPARKELECTRODE
5/16 in.(7 mm)
5/16 in.(7 mm)
FIGURE 19
WHITE RODGERS 36E SERIES GAS VALVE
GAS VALVE SHOWN IN OFF POSITION
MANIFOLDPRESSURE
ADJUSTMENTSCREW
MANIFOLDPRESSURE
OUTLET
ON
OFF
FIGURE 20
HONEYWELL VR8205 SERIES GAS VALVE
GAS VALVE SHOWN IN OFF POSITION
MANIFOLDPRESSURE
ADJUSTMENTSCREW
MANIFOLDPRESSURE
OUTLET
I−Combustion Air Blower Prove (Pressure) Switch (S64)
80MGF series units are equipped with a combustion airprove switch located on the vestibule panel. The switch isconnected to the combustion air blower housing by meansof a flexible silicone hose. It monitors air pressure in thecombustion air blower housing.
The switch is a single-pole single-throw pressure switch
electrically connected to the furnace control. The purpose
of the switch is to prevent burner operation if the combus-
tion air blower is not operating.
FIGURE 21
PROVE SWITCHCOMBUSTION AIR BLOWER
PROVE SWITCHNormally Open
Closes on Negative Pressure
PROVESWITCH
Sensing TubeAttaches to TopSide Of Blower
Top
Bottom
Left
RightBack
Front
On start-up, the switch senses that the combustion airblower is operating. It closes a circuit to the furnace controlwhen pressure inside the combustion air blower increasesabove pressure switch set point (In. negative w.c.). Thepressure sensed by the switch is relative to atmosphericpressure. If the flue becomes obstructed during operation,the switch senses a loss of negative pressure (pressurebecomes more equal with atmospheric pressure) andopens the circuit to the furnace control and gas valve. Theswitch trip pressure is different depending on unit modelnumber. The trip pressure is printed on the side of the limit.
The switch is factory set and is not field adjustable. It is a
safety shut-down control in the furnace and must not be
bypassed for any reason.
II−PLACEMENT AND INSTALLATION
Make sure unit is installed in accordance with installation
instructions and applicable does.
III−START-UP
BEFORE LIGHTING smell all around the appliance area
for gas. Be sure to smell next to the floor because some gas
is heavier than air and will settle on the floor.
Use only your hand to turn the gas control knob. Never use
tools. If the knob will not turn by hand, do not try to repair it,
call a qualified service technician. Force or attempted repair
may result in a fire or explosion.
Page 20
A−Preliminary and Seasonal Checks1− Inspect electrical wiring, both field and factory installed
for loose connections. Tighten as required.
2− Check voltage at disconnect switch. Voltage must be
within range listed on the nameplate. If not, consult the
power company and have voltage condition corrected
before starting unit.
B−Heating Start-Up
1 − STOP! Read the safety information at the beginning
of this section.
2 − Set thermostat to lowest setting.
3 − Turn off all electrical power to appliance.
4 − This appliance is equipped with an ignition device
which automatically lights the burners. Do not try to
light the burners by hand.
5 − Remove access panel.
WARNINGShock and burn hazard.
80MGF units are equipped with a direct spark igni-tion system. Do not attempt to light manually.
6 − White Rodgers 36E Gas Valve −− Switch gas valve
lever to OFF. See figure 19.
Honeywell VR8205 Gas Valve −− Turn knob on gas
valve clockwise to OFF. Do not force. See fig-
ure 20.
7 − Wait five (5) minutes to clear out any gas. If you then
smell gas, STOP! Immediately call your gas supplier
from a neighbor’s phone. Follow the gas supplier’s in-
structions. If you do not smell gas go to next step.
8 − White Rodgers 36E Gas Valve −− Switch gas valve lever
to ON.
Honeywell VR8205 Gas Valve −− Turn knob on gas
valve counterclockwise to ON. Do not force.
9 − Replace access panel.
10− Turn on all electrical power to unit.
11− Set thermostat to desired setting.
12− If the appliance will not operate, follow the instructions
�To Turn Off Gas To Unit" and call your service techni-
cian or gas supplier.
Turning Off Gas To Unit
1 − Set thermostat to lowest setting.
2 − Turn off all electrical power to unit if service is to be
performed.
3 − Remove access panel.
4 − Switch lever on White Rodgers gas valve to OFF; turn
knob on Honeywell valve clockwise to OFF. Do not
force.
5 − Replace lower access panel.
C−Safety or Emergency Shutdown
Turn off unit power. Close manual and main gas valves.
D−Extended Period Shutdown
Turn off thermostat or set to �UNOCCUPIED" mode. Close
all gas valves (both internal and external to unit) to guaran-
tee no gas leak into combustion chamber. Turn off power
to unit. All access panels, covers and vent caps must be in
place and secured.
IV−HEATING SYSTEM SERVICE CHECKS
A−A.G.A./C.G.A. Certification
All units are A.G.A. and or C.G.A. design certified without
modifications. Refer to the 80MGF Operation and Installa-
tion Instruction Manual Information.
B−Gas Piping
Gas supply piping should not allow more than 0.5"W.C.
drop in pressure between gas meter and unit. Supply gas
pipe must not be smaller than unit gas connection.
Compounds used on gas piping threaded joints should be
resistant to action of liquefied petroleum gases.
C−Testing Gas Piping
IMPORTANTIn case emergency shutdown is required, turn offthe main shut-off valve and disconnect the mainpower to unit. These controls should be properlylabeled by the installer.
When pressure testing gas lines, the gas valve must be
disconnected and isolated. Gas valves can be damaged if
subjected to more than 0.5psig (14" W.C.). See figure 22. If
the pressure is equal to or less than 0.5psig (14"W.C.), use
the manual shut−off valve before pressure testing to iso-
late furnace from gas supply.
FIGURE 22
MANUAL MAIN SHUT−OFF VALVE
WILL NOT HOLD TEST PRESSUREIN EXCESS OF 0.5 PSIG (14"W.C.)
GAS VALVECAP
GAS PIPING TEST PROCEDURE
FIELD PROVIDEDLINE PRESSURE TAP
Page 21
When checking piping connections for gas leaks, use pre-
ferred means. Kitchen detergents can cause harmful corro-
sion on various metals used in gas piping. Use of a specialty
Gas Leak Detector is strongly recommended. It is available
through Lennox under part number 31B2001. See Corp.
8411−L10, for further details.
Do not use matches, candles, flame or any other source of
ignition to check for gas leaks.
D−Testing Gas Supply PressureWhen testing supply gas pressure, connect test gauge to
inlet pressure tap (field provided). See figure 22. Check
gas line pressure with unit firing at maximum rate. Low
pressure may result in erratic operation or underfire. High
pressure can result in permanent damage to gas valve or
overfire. For natural gas units, operating pressure at unit
gas connection must be a minimum of 4.5" W.C. For L.P.
gas units, operating pressure at unit gas connection must
be a minimum of 9.0" W.C.
On multiple unit installations, each unit should be checked
separately, with and without other units operating. Supply
pressure must fall within range listed in previous para-
graph.
E−Check Manifold PressureAfter line pressure has been checked and adjusted, check
manifold pressure. Move pressure gauge to outlet pres-
sure tap located on unit gas valve (GV1). Checks of man-
ifold pressure are made as verification of proper regulator
adjustment. Manifold pressure for the 80MGF can be mea-
sured at any time the gas valve is open and is supplying gas
to the unit. Normal manifold pressure for natural gas units is
3.5 in. w.c. For LP/propane gas the correct manifold pres-
sure is 9.0 in. w.c.
IMPORTANTFor safety, connect a shut-off valve between themanometer and the gas tap to permit shut off ofgas pressure to the manometer.
Operating Pressure (outlet) in. W.C.
TABLE 12GAS VALVE REGULATION
3.5 +0 −0.3Natural
L.P. 9.0 + 0.5
Unit (Fuel)
The gas valve is factory set and should not require adjust-
ment. All gas valves are factory regulated. See table 12.
Manifold Adjustment Procedure:
1− Connect a test gauge to outlet pressure tap on gas
valve. Start unit and allow 5 minutes for unit to reach
steady state.
2− While waiting for the unit to stabilize, notice the flame.
Flame should be stable and should not lift from burner.
Natural gas should burn blue. L.P. gas should burn
mostly blue with some orange streaks.
3− After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to values given in
table 12.
NOTE−Shut unit off and remove manometer as soon as
an accurate reading has been obtained. Take care to
replace pressure tap plug.
F− Proper Gas Flow (Approximate)Furnace should operate at least 5 minutes before check-
ing gas flow. Determine time in seconds for two revolu-
tions of gas through the meter. (Two revolutions assures
a more accurate time.) Divide by two and compare to
time in table 13 below. Adjust manifold pressure on gas
valve to match time needed.
NOTE− To obtain accurate reading, shut off all othergas appliances connected to meter.
TABLE 13
GAS METER CLOCKING CHART
Seconds for One Revolution
80mgf Natural LPgUnit 1 cu ft
Dial2 cu ftDial
1 cu ftDial
2 cu ftDIAL
−45 80 160 200 400
−60 60 120 150 300
−75 48 96 120 240
−100 36 72 90 180
−120 30 60 75 150
−140 25 50 64 128
Natural−1000 btu/cu ft LP−2500 btu/cu ft
Page 22
G−High Altitude DerateNOTE−In Canada, certification for installation at alti-
tudes over 4500 ft. (1372m) above sea level is the juris-
diction of the local authorities.
80MGF−1 through −8 Models
This unit does not require gas pressure adjustment, or
pressure switch change when operating at elevations of 0
to 7500 ft. (0 to 2248m). Check gas line pressure with unit
firing. The minimum pressure as shown on the nameplate
for natural and propane gases must be maintained. No ori-
fice change is required.
NOTE−This is the only permissible field derate for this
appliance.
80MGF−9, −10 and −11 Models
Table 14 shows manifold pressure settings for installations
at different altitudes. Refer to table 15 for pressure switch
replacement for models at elevations of 4500 feet (1372m)
and greater.
TABLE 14
ALTITUDEfeet (m)
GAS FUELMANIFOLDPRESSURE
in. W.C. (kPa)
0 − 4500 Natural 3.5 (0.87)0 4500(0 − 1372) Propane/LP 9.5 (2.36)
4500 − 5500 Natural 3.4 (0.86)4500 5500(1372 − 1676) Propane/LP 9.2 (2.29)
5500 − 6500 Natural 3.3 (0.82)5500 6500(1676 − 1981) Propane/LP 8.9 (2.21)
6500 − 7500 Natural 3.2 (0.80)6500 7500(1372 − 2286) Propane/LP 8.6 (2.14)
TABLE 15
Unit Model Pressure Switch Part Number
80MGF−45 No Change
80MGF−60 No Change
80MGF−75 88J8001
80MGF−100 18L2401
80MGF−120 18L2401
80MGF−140 No Change
H−Flame Signal
A microamp DC meter is needed to check the flame signal
on the primary ignition control.
Flame (microamp) signal is an electrical current which
passes from the furnace control through the sensor elec-
trode during unit operation. Current passes from the sen-
sor through the flame to ground to complete a safety cir-
cuit.
To Measure Flame Signal:
1− Place meter in series between furnace control and
sensor wire. Connect the positive (+) lead of meter to
the ignition control sensor connection and the nega-
tive (−) lead of the meter to the sensor wire. See figure
23.
2− Set thermostat for a heating demand and check flame
signal with unit operating. See table 16 for microamp
reading for the various control boards used.
FLAME SIGNAL TEST
FIGURE 23
IGNITIONCON-TROL
�SENSE"TERMINAL
SENSORWIRE
D.C. MICROAMPMETER
FLAMESENSOR
TABLE 16
CONTROLMICROAMP
SIGNALDROP OUT
SIGNAL
Ram 1.0 to 5.0 �1.0
EGC 1.0 to 5.0 �.45
SureLight �.70 �.15
Flame signal may rise above 5 microamps for the first few
seconds after ignition then level off within the range.
WARNINGFire and explosion hazard.These instructions MUST be followed exactly.Can cause a fire or explosion resulting in propertydamage, personal injury or loss of life.
V−TYPICAL OPERATING CHARACTERISTICS
A−Blower Operation and Adjustment
NOTE− The following is a generalized procedure and
does not apply to all thermostat controls.
1− Blower operation is dependent on thermostat control
system.
2− Generally, blower operation is set at thermostat sub-
base fan switch. With fan switch in ON position, blower
operates continuously on heating speed. With fan
switch in AUTO position, blower cycles with demand or
runs continuously while heating or cooling circuit cycles.
3− Depending on the type of indoor thermostat, blower
and entire unit will be off when the system switch is in
OFF position.
B−Temperature RiseTemperature rise for 80MGF units depends on unit input,
blower speed, blower horsepower and static pressure as
marked on the unit rating plate. The blower speed must be
set for unit operation within the range of �AIR TEMP. RISE
°F" listed on the unit rating plate.
FIGURE 24
STATIC PRESSURETEST
MANOMETER
80MGF UNIT
Page 23
To Measure Temperature Rise:
1 − Place plenum thermometers in the supply and return
air plenums. Locate supply air thermometer in the first
horizontal run of the plenum where it will not pick up ra-
diant heat from the heat exchanger.
2 − Set thermostat to highest setting.
3 − After plenum thermometers have reached their high-
est and steadiest readings, subtract the two readings.
The difference should be in the range listed on the unit
rating plate. If the temperature is too low, decrease
blower speed. If temperature is too high, first check
the firing rate. Provided the firing rate is acceptable, in-
crease blower speed to reduce temperature. To
change blower speed taps see the Blower Speed Taps
section in this manual.
C−External Static Pressure
1 − Measure tap locations as shown in figure 24.
2 − Punch a 1/4" diameter hole
in supply and return air ple-
nums. Insert manometer
hose flush with inside edge
of hole or insulation. Seal
around the hose with per-
magum. Connect the zero
end of the manometer to the
discharge (supply) side of the system. On ducted sys-
tems, connect the other end of manometer to the re-
turn duct as above. For systems with non−ducted re-
turns, leave the other end of the manometer open to
the atmosphere.
3 − With only the blower motor running and the evaporator
coil dry, observe the manometer reading. Adjust blow-
er motor speed to deliver the air desired according to
the job requirements.
4 − External static pressure drop must not be more than
0.5" W.C.
5 − Seal around the hole when the check is complete.
D−Blower Speed Taps Leadless Motors
Blower speed tap selection is accomplished by changing the
taps at the blower motor harness connector. Disconnect har-
ness connector from motor to expose speed selectors.
Blower speed selections are listed in table 17.
To Change Blower Speed:
1 − Turn off electric power to furnace.
2 − Remove front panel and blower access door. See
figure 4.
3 − Disconnect blower motor harness from motor.
4 − Select desired speeds for heating and cooling. (Red =
heating, Black = cooling, White = common). See table
17.
TABLE 17
BLOWER SPEED SELECTION
Unit
Factory ConnectedSpeed Taps Speeds
AvailableUnit
Cool (Black) Heat (Red)Available
80MGF2-45 2 4 4
80MGF2-60 2 4 4
80MGF3-60 2 4 4
80MGF2-75 2 3 4
80MGF3-75 2 4 4
80MGF4-75 2 4 5
80MGF3/4-100 2 4 5
80MGF4/5-100 2 5 5
80MGF3/4-120 2 3 5
80MGF4/5-120 2 5 5
80MGF4/5-140 2 3 5
BLOWER SPEED SELECTIONHI LOW
2 3 4 5
2 3 4 5 6
4
5
◊
◊◊
MOTOR PLUG SPEED TAP DESIGNATION
2 3 4◊ 3
TABLE 18
TAPS AVAILABLE
5 − Depress harness connector tab to release wire termi-
nal. Select connector location for new speed (refer to
unit wiring diagram). Insert wire terminal until it is se-
curely in place. See figure 25.
6 − Replace harness connector to motor.
BLOWER SPEED TAP SELEC-TION
Leadless motors only
FIGURE 25
HARNESSCONNECTOR
MOTOR
DEPRESS TAB TO RELEASEWIRE TERMINAL. SELECTCONNECTOR LOCATION FORNEW SPEED (REFER TO UNITWIRING DIAGRAM). INSERTWIRE UNTIL IT IS SECURELYIN PLACE.
Page 24
E−Blower Speed Taps Leaded Motors
−11 Models
Blower speed tap changes are made on the SureLightcontrol board. See figure 8. Unused taps must be securedon dummy terminals "PARK M1" and or "PARK M2" on theSureLight board. The heating tap is connected to the "ACBHEAT " terminal and the cooling tap is connected to the"ACB COOL" terminal. The continuous blower tap is con-nected to the "ACB LOW" terminal.To change existing heat tap, turn off power then switch out
speed tap on "ACB HEAT" with tap connected to "PARK
M1" or "PARK M2". See table 19 for blower motor tap col-
ors for each speed.
TABLE 19
VI−MAINTENANCE
At the beginning of each heating season, the systemshould be checked as follows:
Filters
All 80MGF filters are installed external to the unit. Filtersshould be inspected monthly and cleaned or replacedwhen necessary to assure proper furnace operation. Seetable 20 for filter sizes. Replacement filters for80MGF-45/60/75 units must have a minimum velocity rat-ing of 400 FPM. Replacement filters for80MGF-100/120/140 units require a minimum velocity rat-ing of 625 FPM.
TABLE 20
MODEL NUMBER FILTER SIZE
80MGF−45/60/75 16" X 20" X 1"
80MGF−100/120/140 20" X 20" X 1"
WARNINGBlower door must be securely in place when blow-er and burners are operating. Gas fumes, whichcould contain carbon monoxide, can be drawninto living space resulting in personal injury ordeath.
A−Cleaning Heat Exchanger and Burners
NOTE−Use papers or protective covering in front of fur-
nace while cleaning furnace.
Due to dimples designed in the heatexchanger, cleaning is
not recommended. Removal is for inspection only.
Burners
Burners and burner flame should be inspected at the be-ginning of each heating season. Clean burners, if neces-sary, as outlined below:
1 − Turn off electrical and gas supply to unit.
2 − Remove burner box top.
3 − Remove burner retaining bracket.
4 − Remove burners.
5 − Clean burner insert with bottle brush as shown in fig-
ure 26.
NOTE−Use papers or protective covering in front of fur-
nace while cleaning furnace.
FIGURE 26
CLEANING BURNERS
BOTTLEBRUSH
BURNER
6 − Use bottle brush to clean inside of each burner.
7 − Replace burners and burner retaining bracket, mak-ing sure burners are properly seated in slots on trayand orifice in manifold.
8 − Check electrode gap using appropriately sized twist
drills or feeler gauges. Gap should be between 2.79 to
3.56mm (0.110 and 0.140 inches).
9 − Reinstall burner box top.
CAUTIONSome soaps used for leak detection are corrosiveto certain metals. Carefully rinse piping thorough-ly after leak test has been completed. Do not usematches, candles, flame or other sources of igni-tion to check for gas leaks.
10 − Restore electrical power and gas supply. Follow light-ing instructions on front of unit. Check the following:
appearance of burner flame, burner pressure, gas flowand temperature rise. Make adjustments, if necessary.See adjustments section.
B−Supply Air Blower1 − Check and clean blower wheel.
2 − Motors used on the Lennox 80MGF series units arepermanently lubricated and need no further lu-brication.
Page 25
C−Flue and Chimney
Flue must conform to all AGA/GAMA venting require-
ments. Flue pipe deteriorates from the inside out and must
be disconnected in order to check thoroughly. Check flue
pipe, chimney and all connections for tightness and to
make sure there is no blockage or leaks.
D−Electrical
1 − Check all wiring for loose connections.
2 − Check for correct voltage.
3 − Check amp−draw on blower motor.
CAUTIONPotential for gas leaks, fire or explosion.Some soaps used for leak detection are corrosiveto certain metals. Carefully clean piping thor-oughly after leak detection has been completed.Can cause damage to piping resulting in gasleaks, fire or explosion.
FIGURE 27
HEAT EXCHANGER REMOVAL (unit shown in horizontal position)
REMOVE SCREWS (4)
SLIDE ENTIRE ASSEMBLY OUT OF CABINET
Front
Right
TopBottom
Left
Back
Page 26
VII−WIRING AND SEQUENCE OF OPERATION
2 3
5
6
8
74
1
80MGF WITH RAM CONTROL
1- When disconnect is closed, 120V is routed throughdoor interlock switch (S51) to feed the line voltageside of the furnace control (A3) and transformer T1 pri-mary. Door interlock switch must be closed for A3 andT1 to receive voltage.
2- T1 supplies 24VAC to terminal �24VAC" on A3. In turn,terminal �R" of A3 supplies 24VAC to terminal �RC" ofthe indoor thermostat (not shown).
3- When there is a call for heat, W1 of the thermostat en-ergizes W of the furnace control with 24VAC.
4- CMB BLWR of the blower control energizes the com-bustion air blower (B6). When the combustion airblower nears full speed, combustion air prove switch(S18) closes.
5- When S18 closes, assuming the flame rollout switch(S47) primary limit (S10) and secondary limits (S21)are closed, the furnace control begins a 45 secondtime-delay (pre-purge).
6- At the end of the pre-purge cycle, the furnace controlsimultaneously opens the gas valve and sends highvoltage to the spark electrode.
7- When flame is sensed, the furnace control begins a 45second delay before energizing the indoor blower.
8- When heat demand is satisfied, W1 of the thermostatde-energizes W of the furnace control and the furnacecontrol immediately de-energizes the gas valve. Thecombustion air blower runs for 5 seconds (post-purge)before being de-energized. Also, the indoor blowerruns for a designated period (90−240 seconds) as setby switches on furnace control.
Page 27
80MGF TROUBLESHOOTING SEQUENCE
NORMAL HEATING MODE ABNORMAL HEATING MODE
LED: SLOW FLASH RATE
THERMOSTAT CALLS FOR HEAT
LED: FAST FLASH RATE
FLAME OFF?
CONTROL SELF−CHECK OKAY?
HI LIMIT SWITCH CLOSED?
PRESSURE SWITCH OPEN?
COMBUSTION AIR BLOWER ON?
PRESSURE SWITCH CLOSED?
PREPURGE (45 seconds)
IGNITION TRIAL (7 seconds) −− START IGNITIONSPARK, OPEN MAIN GAS VALVE. INCREMENT
TRIAL REGISTER. HAS FLAME BEENREGISTERED WITHIN 7 SECONDS?
SYSTEM FAN ON. (Fixed 45−second delay)
FLAME SENSE OKAY?
FLAME CONTINUOUSLY CHECKED?
ROLLOUT SWITCHES CLOSED
HI LIMIT SWITCH CLOSED?
PRESSURE SWITCH CLOSED?
THERMOSTAT OPENS
LED: SLOW FLASH RATE
COMB. AIR BLOWER OFF (5 sec. delay)
FAN OFF (After selected 90, 120,180, or 240 delay)?
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
LOCKOUT: MAIN VALVE OFFCOMB. AIR AND SYSTEM FANS ON
RESET THERMOSTATLED: 5 flash if flame sensed with valve off
LED: Steady on if control board failure
NO
NO
CHECK TO SEE IF MAIN VALVE IS OFF.SEQUENCE HOLDS UNTIL HI LIMIT CLOSES.
LED: 4 flashes.
NO
CHECK TO SEE IF MAIN VALVE IS OFF.SEQUENCE HOLDS UNTIL PRES. SWITCH OPENS.
LED: 3 flashes.
CHECK TO SEE IF MAIN VALVE IS OFF.SEQUENCE HOLDS UNTIL PRES. SWITCH CLOSES.
LED: Fast flash rate.
MAIN VALVE AND SPARK ARE OFF.INCREMENT TRIAL REGISTERTHREE TRIALS COMPLETED?
NO
NO
NO
IGNITION RESET PERIODCOMBUSTION & SYSTEM FANS OFF.
IS 60 MIN. RESET PERIOD COMPLETE?LED: Fast flash rate.
MAIN VALVE AND SPARK OFF.
START IGNITION SPARK (IN 0.8 SEC. MAXIMUM).HAS FLAME BEEN DETECTED WITHIN 7 SEC.?
SEQUENCE HOLDS. MAIN VALVE OFF.COMBUSTION AND SYSTEM FANS ON.
RESET OR REPLACE ROLLOUT SWITCH.LED: 4 flashes.
MAIN VALVE OFF. COMBUSTION & SYSTEM FANS ON.SEQUENCE HOLDS UNTIL SWITCH CLOSES.
LED: 4 flashes for hi limit.LED: 3 flashes for pressure switch.
SWITCH CLOSED
COMBUSTION FAN ON. SYSTEM FAN OFF.(AFTER DELAY TO OFF INTERVAL COMPLETED.)
LED: Fast flash rate.
NO
YES
YES
NO
NO
YES
NO
NO
NO
YES
Page 28
80MGF TROUBLESHOOTING SEQUENCE − COOLING
YES
THERMOSTAT CALLS FOR COOLING.
LED: Slow flash rate.REMAINS UNCHANGED THROUGHOUT COOLING CYCLE.
NO
COMPRESSOR CONTACTOR AND SYSTEM FANENERGIZED AT COOLING SPEED AFTER
1 SECOND DELAY.
THERMOSTAT OPENS.
COMPRESSOR OFF.
SYSTEM FAN OFF AFTER COMPLETINGSELECTED DELAY INTERVAL
(At dip switches).
80MGF TROUBLESHOOTING SEQUENCE − FAN ONLY
MANUAL FAN SELECTION MADE AT THERMOSTAT.CONTROL ENERGIZES SYSTEM FAN
AT HEATING SPEED.
THERMOSTAT CALLS FOR HEAT.
LED: Slow flash rate.REMAINS UNCHANGED THROUGHOUT SEQUENCE.
THERMOSTAT CALLS FOR COOLING.SYSTEM FAN REMAINS ON HEATING SEQUENCE AND
RUNS THROUGH COMPLETION.
SYSTEM FAN SWITCHEDTO COOLING SPEED. COOLING
SEQUENCE RUNS TO COMPLETION.
SYSTEM FAN ON AT HEATING SPEEDUNTIL MANUAL FAN IS SWITCHED
OFF AT THERMOSTAT.
YES NO
LED CODES
SLOW FLASH
FAST FLASH
2 FLASH
3 FLASH
4 FLASH
5 FLASH
STEADY ON
NORMAL OPERATION. NO CALL FOR HEAT.
NORMAL OPERATION. CALL FOR HEAT.
SYSTEM LOCKOUT. FAILURE TO DETECT OR SUSTAIN FLAME.
PRESSURE SWITCH OPEN OR CLOSED.
HIGH LIMIT OR ROLLOUT SWITCH OPEN.
FLAME SENSED AND GAS VALVE NOT ENERGIZED.
CONTROL BOARD FAILURE.
.
Page 29
80MGF WITH EGC−2 IGNITION CONTROL1 − When disconnect is closed, 120V is routed through door
interlock switch (S51) to feed the line voltage side of theignition control (A3) and transformer T1 primary. Door in-terlock switch must be closed for A3 and T1 to receivevoltage.
2 − T1 supplies 24VAC to terminal �24VAC" on A3. In turn,terminal �R" of A3 supplies 24VAC to terminal �R" of theindoor thermostat (not shown).
3 − When there is a call for heat, W1 of the thermostat en-ergizes W of the ignition control with 24VAC.
4 − CAB of the ignition control energizes the combustion airblower (B6). When the combustion air blower nearsfull speed, combustion air prove switch (S18)closes.
5 − When S18 closes, assuming primary limit (S10) and
secondary limit (S21) are closed, a 15 second pre−purge
begins. After the pre−purge period the ignition control
starts ignition spark and opens main gas valve.
6 − After 45 seconds, ignition control (A3) energizes the
indoor blower (B3).
7 − When heat demand is satisfied, W1 of the thermostat de-
energizes W of the ignition control and the gas valve is
immediately de-energized. The combustion air blower
immediately stops. The indoor blower runs for a desig-
nated fan �off" period (60−240 seconds) as set by jumper
on ignition control.
Page 30
80MGF WITH EGC−2 HEATING SEQUENCE OF OPERATION
NORMAL HEATING MODE ABNORMAL HEATING MODE
LED: SLOW FLASH RATE
THERMOSTAT CALLS FOR HEAT
LED: FAST FLASH RATE
FLAME OFF?
CONTROL SELF−CHECK OKAY?
COMB. AIR BLOWER PRESSURE SWITCH OPEN?
PRESSURE SWITCH CLOSED WITHIN 2.5 MIN.?
COMB. AIR BLOWER PREPURGE (15 seconds)
HAS FLAME REGISTERED WITHIN 10 SECONDSAFTER IGNITION TRIAL?
YES
YES
YES
YES
NO
CONTROL MAIN POWER �ON"
ROLL−OUT SWITCH CLOSED
YES
GAS VALVE OFF. COMB. BLOWER ON. INDOORBLOWER ON HEAT SPEED. SEQUENCE HOLDS UNTIL
NO FLAME SENSED OR MAIN POWER IS INTERRUPTEDAND RESET. DIAG. CODE: 1− FLASHING; 2−OFF(FLAME SENSED WITHOUT VALVE ENERGIZED)
GAS VALVE, COMB. BLOWER AND INDOOR BLOWER(WITH DELAY) OFF. REMOVE POWER TO RESET
CONTROL. DIAG. CODE: BOTH ON (CONTROLSELF−CHECK FAILURE OR INCORRECT WIRING)
GAS VALVE, COMB. BLOWER AND INDOOR BLOWER(WITH DELAY) OFF. SEQUENCE HOLDS UNTIL
ROLL−OUT SWITCH IS MANUALLY CLOSED.DIAG. CODE: 1−ON;
2−FLASHING (FLAME ROLL−OUT OPEN)
GAS VALVE, COMB. BLOWER AND INDOOR BLOWER(WITH DELAY) OFF. SEQUENCE HOLDS UNTIL
PRESSURE SWITCH CLOSES OR THERMOSTATRESETS CONTROL. DIAG. CODE: 1−OFF;
2−FLASHING (C.A.B. PRESSURE SWITCH OPEN)
COMBUSTION AIR BLOWER ON?HTG ACC. TERM. ENERGIZED.
PRESSURE SWITCH WATCHGUARD CONDITION:GAS VALVE, COMB. BLOWER AND INDOOR BLOWER
(WITH DELAY) OFF. DIAG. CODE: 1−OFF /2−FLASHING (C.A.B. PRESSURE SWITCH OPEN) IS 5
MINUTE RESET PERIOD COMPLETE?
INDOOR AIR BLOWER ON. (Fixed 45−second delay)
PRIMARY/SECONDARY LIMITS MONITORED INHEAT CYCLE. ARE SWITCHES CLOSED?
YESNO
GAS VALVE OFF. COMB. BLOWER OFF. INDOORBLOWER ON UNTIL LIMIT CLOSES. DIAG.CODE: 1−FLASHING / 2−ON (LIMIT OPEN)
IS LIMIT NOW CLOSED?PRESSURE SWITCH CLOSED?
YES
HAS PRIMARY LIMIT OPENED 5 TIMES DURINGONE UNSATISFIED HEAT DEMAND. IF YES,
SYSTEM GOES INTO 60 MIN.WATCHGUARD.DIAG. CODE: 1−FLASHING / 2−ON
IF NO, GO TO �COMB. AIR BLOWER ON?"
THERMOSTAT OPENS
LED: SLOW FLASH RATE
COMB. AIR BLOWER OFF (5 sec. delay)HTG ACC. TERM.DE−ENERGIZED.
INDOOR AIR BLOWER OFF (After selected 60, 90,120, 180, or 240 delay)?
GAS VALVE, COMB. BLOWER AND INDOOR BLOWER(WITH DELAY) OFF. DIAG. CODE: 1−OFF / 2−FLASHING
(C.A.B. PRESSURE SWITCH OPEN) HAS C.A.B.PRESSURE SWITCH CLOSED IN 2.5 MINUTES?
NO
NO
NO
NO
NO
YES
NO
GAS VALVE OFF. COMB. BLOWER ON. INDOORBLOWER (WITH 45 DELAY) ON. HAS CONTROL FAILEDFLAME SENSE 5 TIMES DURING ONE HEAT DEMAND?IF YES, SYSTEM GOES INTO 60 MIN.WATCHGUARD.DIAG. CODE: 1−ALT. FLASHING / 2−ALT. FLASHING IF
NO, GO TO �COMB. AIR BLOWER ON?"IS FLAME SENSED AFTER 10 SECOND
FLAME RECTIFICATION PERIOD?
NO
NO
HAS CONTROL RESET IGNITION SEQUENCE 5 TIMESIF YES, SYSTEM GOES INTO 60 MIN. WATCHGUARD.DIAG. CODE: 1−ALT. FLASHING / 2−ALT. FLASHING IF
NO, GO TO �COMB. AIR BLOWER ON?"
YES
YES
YES
YES
IGNITION TRIAL (10 seconds) −− START IGNITIONSPARK, OPEN MAIN GAS VALVE.
YES
Page 31
80MGF WITH EGC−2 COOLING SEQUENCE OF OPERATION
YES
THERMOSTAT CALLS FOR COOLING.
LED: Slow flash rate.REMAINS UNCHANGED THROUGHOUT COOLING CYCLE.
NO
COMPRESSOR CONTACTOR AND SYSTEM FANENERGIZED AT COOLING SPEED AFTER
1 SECOND DELAY. ACC TERMINAL ENERGIZED.
THERMOSTAT OPENS.
COMPRESSOR OFF.
SYSTEM FAN AND ACC TERMINAL OFF AFTER 0 SECONDS.
80MGF WITH EGC−2 MANUAL CONTINUOUS FAN SEQUENCE OF OPERATION
CONTINUOUS FAN SELECTION MADE AT THERMOSTAT.CONTROL ENERGIZES SYSTEM FAN AT HEAT SPEED.
ACC TERMINAL ENERGIZED.
THERMOSTAT CALLS FOR HEAT.
LED: Slow flash rate.REMAINS UNCHANGED THROUGHOUT SEQUENCE.
THERMOSTAT CALLS FOR COOLING.SYSTEM FAN REMAINS ON HEATING SPEED AFTER
SELECTED DELAY. ACC TERM. REMAINS ENERGIZED.
SYSTEM FAN SWITCHED TO COOLING SPEED. ACC TERMINAL REMAINS ENERGIZED.
SYSTEM FAN SWITCHES TO CONTINUOUS SPEEDAND ENERGIZES ACC TERMINAL. BOTH REMAIN ON
UNTIL CONTINUOUS FAN IS SWITCHED OFF AT THERMOSTAT.
YES NO
THERMOSTAT OPENS.
THERMOSTAT OPENS.
SYSTEM FAN SWITCHED OFF AFTER DELAY.ACC TERMINAL DE−ENERGIZED.
HTG ACC. TERM. ENERGIZED WITH COMB. AIR BLOWER.
Page 32
80MGF WITH EGC−1 IGNITION CONTROL1 − When disconnect is closed, 120V is routed through door
interlock switch (S51) to feed the line voltage side of theignition control (A3) and transformer T1 primary. Door in-terlock switch must be closed for A3 and T1 to receivevoltage.
2 − T1 supplies 24VAC to terminal �24VAC" on A3. In turn,terminal �R" of A3 supplies 24VAC to terminal �R" of theindoor thermostat (not shown).
3 − When there is a call for heat, W1 of the thermostat en-ergizes W of the ignition control with 24VAC.
4 − CAB of the ignition control energizes the combustion airblower (B6). When the combustion air blower nearsfull speed, combustion air prove switch (S18)closes.
5 − When S18 closes, assuming primary limit (S10) and
secondary limit (S21) are closed, a 15 second pre−purge
begins. After the pre−purge period the ignition control
starts ignition spark and opens main gas valve.
6 − After 45 seconds, ignition control (A3) energizes the
indoor blower (B3).
7 − When heat demand is satisfied, W1 of the thermostat de-
energizes W of the ignition control and the gas valve is
immediately de-energized. The combustion air blower
immediately stops. The indoor blower runs for a desig-
nated fan �off" period (60−240 seconds) as set by jumper
on ignition control.
Page 33
80MGF WITH EGC−1 HEATING SEQUENCE OF OPERATION
NORMAL HEATING MODE ABNORMAL HEATING MODE
LED: SLOW FLASH RATE
THERMOSTAT CALLS FOR HEAT
LED: FAST FLASH RATE
FLAME OFF?
CONTROL SELF−CHECK OKAY?
COMB. AIR BLOWER PRESSURE SWITCH OPEN?
PRESSURE SWITCH CLOSED WITHIN 2.5 MIN.?
COMB. AIR BLOWER PREPURGE (15 seconds)
HAS FLAME REGISTERED WITHIN 10 SECONDSAFTER IGNITION TRIAL?
YES
YES
YES
YES
NO
CONTROL MAIN POWER �ON"
ROLL−OUT SWITCH CLOSED
YES
GAS VALVE OFF. COMB. BLOWER ON. INDOORBLOWER ON HEAT SPEED. SEQUENCE HOLDS UNTIL
NO FLAME SENSED OR MAIN POWER IS INTERRUPTEDAND RESET. DIAG. CODE: 1− FLASHING; 2−OFF(FLAME SENSED WITHOUT VALVE ENERGIZED)
GAS VALVE, COMB. BLOWER AND INDOOR BLOWER(WITH DELAY) OFF. REMOVE POWER TO RESET
CONTROL. DIAG. CODE: BOTH ON (CONTROLSELF−CHECK FAILURE OR INCORRECT WIRING)
GAS VALVE, COMB. BLOWER AND INDOOR BLOWER(WITH DELAY) OFF. SEQUENCE HOLDS UNTIL
ROLL−OUT SWITCH IS MANUALLY CLOSED.DIAG. CODE: 1−ON;
2−FLASHING (FLAME ROLL−OUT OPEN)
GAS VALVE, COMB. BLOWER AND INDOOR BLOWER(WITH DELAY) OFF. SEQUENCE HOLDS UNTIL
PRESSURE SWITCH CLOSES OR THERMOSTATRESETS CONTROL. DIAG. CODE: 1−OFF;
2−FLASHING (C.A.B. PRESSURE SWITCH OPEN)
COMBUSTION AIR BLOWER ON?HTG ACC. TERM. ENERGIZED?
PRESSURE SWITCH WATCHGUARD CONDITION:GAS VALVE, COMB. BLOWER AND INDOOR BLOWER
(WITH DELAY) OFF. DIAG. CODE: 1−OFF /2−FLASHING (C.A.B. PRESSURE SWITCH OPEN) IS 5
MINUTE RESET PERIOD COMPLETE?
INDOOR AIR BLOWER ON. (Fixed 45−second delay)
PRIMARY/SECONDARY LIMITS MONITORED INHEAT CYCLE. ARE SWITCHES CLOSED?
YESNO
GAS VALVE OFF. COMB. BLOWER OFF. INDOORBLOWER ON UNTIL LIMIT CLOSES. DIAG.CODE: 1−FLASHING / 2−ON (LIMIT OPEN)
IS LIMIT NOW CLOSED?PRESSURE SWITCH CLOSED?
YES
HAS PRIMARY LIMIT OPENED 5 TIMES DURINGONE UNSATISFIED HEAT DEMAND. IF YES,
SYSTEM GOES INTO 60 MIN.WATCHGUARD.DIAG. CODE: 1−FLASHING / 2−ON
IF NO, GO TO �COMB. AIR BLOWER ON?"
THERMOSTAT OPENS
LED: SLOW FLASH RATE
COMB. AIR BLOWER OFF (5 sec. delay)HTG ACC. TERM. DE−ENERGIZED.
INDOOR AIR BLOWER OFF (After selected 60, 90,120, 180, or 240 delay)?
GAS VALVE, COMB. BLOWER AND INDOOR BLOWER(WITH DELAY) OFF. DIAG. CODE: 1−OFF / 2−FLASHING
(C.A.B. PRESSURE SWITCH OPEN) HAS C.A.B.PRESSURE SWITCH CLOSED IN 2.5 MINUTES?
NO
NO
NO
NO
NO
YES
NO
GAS VALVE OFF. COMB. BLOWER ON. INDOORBLOWER (WITH 45 DELAY) ON. HAS CONTROL FAILEDFLAME SENSE 5 TIMES DURING ONE HEAT DEMAND?IF YES, SYSTEM GOES INTO 60 MIN.WATCHGUARD.DIAG. CODE: 1−ALT. FLASHING / 2−ALT. FLASHING IF
NO, GO TO �COMB. AIR BLOWER ON?"IS FLAME SENSED AFTER 10 SECOND
FLAME RECTIFICATION PERIOD?
NO
NO
HAS CONTROL RESET IGNITION SEQUENCE 5 TIMESIF YES, SYSTEM GOES INTO 60 MIN. WATCHGUARD.DIAG. CODE: 1−ALT. FLASHING / 2−ALT. FLASHING IF
NO, GO TO �COMB. AIR BLOWER ON?"
YES
YES
YES
YES
IGNITION TRIAL (10 seconds) −− START IGNITIONSPARK, OPEN MAIN GAS VALVE.
YES
Page 34
80MGF WITH EGC−1 COOLING SEQUENCE OF OPERATION
YES
THERMOSTAT CALLS FOR COOLING.
LED: Slow flash rate.REMAINS UNCHANGED THROUGHOUT COOLING CYCLE.
NO
COMPRESSOR CONTACTOR AND SYSTEM FANENERGIZED AT COOLING SPEED AFTER
1 SECOND DELAY. ACC TERMINAL ENERGIZED.
THERMOSTAT OPENS.
COMPRESSOR OFF.
SYSTEM FAN AND ACC TERMINAL OFF AFTER 0 SECONDS.
80MGF WITH EGC−1 MANUAL CONTINUOUS FAN SEQUENCE OF OPERATION
CONTINUOUS FAN SELECTION MADE AT THERMOSTAT.CONTROL ENERGIZES SYSTEM FAN AT LOW SPEED.
ACC TERMINAL ENERGIZED.
THERMOSTAT CALLS FOR HEAT.
LED: Slow flash rate.REMAINS UNCHANGED THROUGHOUT SEQUENCE.
THERMOSTAT CALLS FOR COOLING.SYSTEM FAN SWITCHES TO HEAT SPEED AFTER
SELECTED DELAY. ACC TERM. REMAINS ENERGIZED.
SYSTEM FAN SWITCHED TO COOLING SPEED. ACC TERMINAL REMAINS ENERGIZED.
SYSTEM FAN SWITCHES TO CONTINUOUS SPEEDAND ENERGIZES ACC TERMINAL. BOTH REMAIN ON
UNTIL CONTINUOUS FAN IS SWITCHED OFF AT THERMOSTAT.
YES NO
THERMOSTAT OPENS.
THERMOSTAT OPENS.
SYSTEM FAN SWITCHED OFF AFTER DELAY.ACC TERMINAL DE−ENERGIZED.
HTG ACC. TERM. ENERGIZEDWITH COMB. AIR BLOWER.
Page 35
80MGF WITH SURELIGHT IGNITION CONTROL1 − When there is a call for heat, W1 of the thermostat en-
ergizes W of the furnace control with 24VAC.
2 − S10 primary limit switch and S47 rollout switch are
closed. Call for heat can continue.
3 − SureLight control energizes combustion air blower
B6. Combustion air blower runs until S18 combustion
air prove switch closes (switch must close within 2−1/2
minutes or control goes into 5 minute Watchguard
Pressure Switch delay). Once S18 closes, a 15−sec-
ond pre−purge follows.
4 − SureLight control energizes ignitor. A 20−second
warm−up period begins.
5 − Gas valve opens for a 4−second trial for ignition.
6 − Flame is sensed, gas valve remains open for the heat
call.
7 − After 45−second delay, SureLight control energizes
indoor blower B3.
8 − When heat demand is satisfied, W1 of the indoor ther-
mostat de−energizes W of the SureLight control which
de−energizes the gas valve. Combustion air blower
B6 continues a 5−second post−purge period, and in-
door blower B3 completes a selected OFF time delay.
Page 36
SURELIGHT CONTROLHEATING SEQUENCE OF OPERATION
NORMAL HEATING MODE ABNORMAL HEATING MODE
CONTROL SELF−CHECK OKAY?
BURNER OFF?(CONTINUOUS FLAME CHECK)
NORMAL OPERATION:LED #1 −− SLOW FLASHLED #2 −− SLOW FLASH
YES
YES
YES
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.INDOOR BLOWER DELAY OFF.
LED #1 ONLED #2 ON
(RESET CONTROL BY TURNING MAIN POWER OFF.)
POLARITY REVERSED.LED #1 −− FAST FLASHLED #2 −− SLOW FLASH
POWER ON
COMBUSTION AIR BLOWER ON FOR 1 SECOND.
TURN INDUCER ON FOR 1 SECOND.IS POLARITY REVERSED?
ROLLOUT SWITCH CLOSED?
THERMOSTAT CALLS FOR HEAT:LED #1 −− FAST FLASHLED #2 −− FAST FLASH
IS COMBUSTION AIRPRESSURE SWITCH OPEN?
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.INDOOR BLOWER OFF WITH DELAY.LED #1 −− ON. LED #2 −− SLOW FLASH.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.
GAS VALVE OFF. COMBUSTION AIR BLOWER ON.INDOOR BLOWER ON HEATING SPEED.
LED #1 −− SLOW FLASHLED #2 −− OFF
GAS VALVE OFF.COMBUSTION AIR BLOWER OFF.
INDOOR BLOWER OFF WITH DELAY.LED #1 OFF
LED #2 SLOW FLASH(Sequence holds until pressure switchcloses or thermostat resets control.)
NOYES
NO
IS THEREPROPER GROUND?
IS VOLTAGEABOVE 75 VOLTS?
LOW VOLTAGE SIGNAL AT LED HOLDSUNTIL VOLTAGE RISES ABOVE 75 VOLTS.
NOYES
NO
SIGNAL IMPROPERGROUND AT LED.SIGNAL HOLDSUNTIL UNIT IS
PROPERLYGROUNDED.
NO
NO
IS COMBUSTION AIR BLOWER ENERGIZED? (HTG ACC TERMINAL IS ENERGIZED WITH C.A.B.)
HAS COMBUSTION AIR PRESSURESWITCH CLOSED IN 2.5 MINUTES?
YES
YESPRESSURE SWITCH IS IN WATCHGUARD MODE.
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.INDOOR BLOWER OFF WITH DELAY.
LED #1 −− OFF. LED #2 −− SLOW FLASH.IS 5-MINUTE RESET PERIOD COMPLETE?
NO
15-SECOND COMBUSTION AIR BLOWER PREPURGEINITIATED BY CLOSED PRESSURE SWITCH.
YES
YES
CONTINUED NEXT PAGE
YES
NO
GAS VALVE OFF. COMBUSTION AIR BLOWER ON.INDOOR BLOWER ON.
LED #1 ALTERNATING FAST FLASHLED#2 ALTERNATING FAST FLASHCHECK FOR BROKEN IGNITOR OR
OPEN IGNITOR CIRCUIT
Page 37
NORMAL HEATING MODE ABNORMAL HEATING MODE
FLAME RECTIFICATION CURRENTCHECK. CAN FLAME BE PROVEN WITHIN4 SECONDS AFTER GAS VALVE OPENS?
(�0.15 microamps)
FLAME PRESENT?
INDOOR BLOWER ON DELAY BEGINS(45 seconds.)
PRIMARY AND SECONDARY LIMITSWITCHES CLOSED?
COMBUSTION AIR PRESSURESWITCH CLOSED?
LOW FLAME SIGNAL(Does not affect operation of control)
LED #1 −− SLOW FLASHLED #2 −− FAST FLASH
GAS VALVE DE−ENERGIZED.COMBUSTION AIR INDUCER
DE−ENERGIZED.INDOOR BLOWERON UNTIL SWITCH CLOSES.LED #1
−− SLOW FLASH. LED #2 −− ON.IS LIMIT SWITCH CLOSED?
GAS VALVE DE−ENERGIZED.COMBUSTION AIR INDUCER ON.
INDOOR BLOWER OFF WITH DELAYLED #1 −− OFF. LED #2 −− SLOW FLASH.
HAS CAB SWITCH CLOSED IN 2.5 MINUTES?
15-SECOND COMBUSTION AIR INDUCER PREPURGEINITIATED BY CLOSED PRESSURE SWITCH.
YES
IGNITOR WARM-UP −− 20 SECONDS.
YES
4-SECOND TRIAL FOR IGNITION.GAS VALVE OPENS. IGNITOR ENERGIZED FOR
1 SECOND AFTER VALVE OPENS.NO FLAME SENSED DURING THIS PERIOD.
BOARD 97L48 ONLY: IGNITOR ENERGIZED FOR THEFULL 4−SECOND TRIAL FOR IGNITION.
YES
FLAME STABILIZATION PERIOD.
GAS VALVE OFF. COMBUSTION AIR INDUCER ON.INDOOR BLOWER OFF.
HAS CONTROL FAILED TO SENSE FLAME FORFIVE CONSECUTIVE TRIES DURING A SINGLE
HEAT DEMAND?
IGNITION WATCHGUARD MODE. GAS VALVE OFF.COMBUSTION AIR INDUCER OFF.
INDOOR BLOWER OFF WITH DELAYLED 1 ALT. SLOW FLASH LED 2 ALT SLOW FLASH
IS 60-MINUTE RESET PERIOD COMPLETE?
YES
4 SECONDS
YES
HAS CONTROL RESET IGNITIONSEQUENCE FOUR TIMES?
FLAME SIGNAL ABOVE 0.7 MICROAMPS?
YES
YES
HAS PRIMARY/SECONDARY LIMIT RESET.(See table 9 DIAGNOSTIC CODES for limit reset operation)
YES
ROLLOUT SWITCH CLOSED?
GAS VALVE POWER OFF. COMBUSTION AIR INDUCER POWER OFF.
INDOOR BLOWER OFF WITH DELAYLED #1 −− ON. LED #2 −− SLOW FLASH.
SEQUENCE HOLDS UNTIL ROLLOUT SWITCH IS RESET
YES
THERMOSTAT DEMAND SATISFIED.
LED #1 & #2 SIMULTANEOUS SLOW FLASHES.
YES
NO
5-MINUTE PRESSURE SWITCHWATCHGUARD MODE.
YES
IS THERE A PROPER GROUND?
IS VOLTAGE ABOVE 75 VOLTS?
IS IGNITOR INTACT AND CONNECTED?
LEDS SIGNAL ALTERNATINGFAST FLASH
NO YES
YESYES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
NO
NO
NO
NO
YES
YES
LIMIT SWITCH WATCH GUARDMODE. GAS VALVE OFF.COMB. AIR INDUCER OFF. IN-DOOR BLOWER OFF WITHDELAY. LED#1−SLOW FLASHLED#2− ON. IS 60MINUTE RE-SET PERIOD COMPLETE.?
YES
YES
COMB. AIR INDUCER CONTINUES 5-SECOND POST PURGEAFTER T’STAT DEMAND IS SATISFIED. INDOOR AIR BLOWER
COMPLETES SELECTED �OFF" DELAY BEFORE SHUTTING OFF.ACB.HEAT SPEED, HTG ACC TERM. AND ACC TERM. OFF.
Page 38
SURELIGHT CONTROLCOOLING SEQUENCE OF OPERATION
NORMAL COOLING MODE ABNORMAL COOLING MODE
IGNITION CONTROL MAIN POWER ON.
CONTROL SELF DIAGNOSTIC CHECK.IS CONTROL OPERATING NORMALLY?
YES
SIGNAL POLARITY REVERSED AT LED.
POWER ON
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.INTERRUPT MAIN POWER TO RESET CONTROL.
YES
TURN INDUCER ON FOR 1 SECOND.
IS POLARITY REVERSED?
ROLLOUT SWITCH MONITORED CONTINUOUSLY.IS ROLLOUT SWITCH CLOSED?
CHECK FOR MAIN BURNER FLAME SENSE.IS MAIN BURNER FLAME OFF?
LED: SLOW FLASH RATE REMAINS UNCHANGEDTHROUGHOUT COOLING CYCLE.
THERMOSTAT CALLS FOR COOLING.
COMPRESSOR CONTACTOR AND SYSTEM FANENERGIZED WITH 0-SECOND DELAY. ACB COOL
SPEED AND ACC. TERMINAL IS ENERGIZED.
COMPRESSOR OFF.
THERMOSTAT OPENS.
SYSTEM FAN AND ACC. TERM. OFFWITH 0-SECOND DELAY.
NO
YES
NO
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.SEQUENCE HOLDS UNTIL ROLLOUT SWITCH CLOSES.
NO
GAS VALVE OFF. COMBUSTION AIR BLOWER OFF.INDOOR BLOWER OFF WITH NORMAL DELAY.
SIGNAL CIRCUIT BOARD FAILURE AT LED.SEQUENCE HOLDS UNTIL FLAME IS NOT SENSED.
NO
IS THEREPROPER GROUND?
IS VOLTAGEABOVE 75 VOLTS?
LOW VOLTAGE SIGNAL AT LET HOLDSUNTIL VOLTAGE RISES ABOVE 75 VOLTS.
NOYES
NO
SIGNAL IMPROPERGROUND AT LED.SIGNAL HOLDSUNTIL UNIT IS
PROPERLYGROUNDED.
Page 39
SURELIGHT CONTROLCONTINUOUS LOW SPEED FAN SEQUENCE OF OPERATION
LED: SLOW FLASH RATE REMAINSUNCHANGED THROUGHOUT SEQUENCE.
MANUAL FAN SELECTION MADE AT THERMOSTAT.CONTROL (G) ENERGIZES SYSTEM FAN AT ACBLOW SPEED. ACC. TERMINAL IS ENERGIZED.
THERMOSTAT CALLS FOR HEAT (W).
THERMOSTAT CALLS FOR COOLING.
BOARD NO. 63K8901SYSTEM FAN DE−ENERGIZED. SYSTEM FANENERGIZES ON ACB HEAT SPEED AFTER
NORMAL DELAY.
THERMOSTAT OPENS. COMBUSTION AIRAND HTG ACC TERMINAL DE−ENERGIZE.
SYSTEM FAN SWITCHED TO ACB COOLSPEED. ACC. TERM. REMAINS ON.
THERMOSTAT OPENS.
BOARD 63K89: SYSTEM FAN OFF. ACC. TERM.OFF. (AFTER OFF DELAY COMPLETED).
MANUAL FAN SELECTION MADE AT THERMOSTAT.CONTROL (G) ENERGIZES SYSTEM FAN AT ACB
LOW SPEED. ACC. TERM. ENERGIZED.
NO YES
YESNO
HTG ACC. TERM. ENERGIZES WITH COMB. AIR BLOWER.
BOARD NO. 24L85, 56L83, 97L48SYSTEM FAN SWITCHES TO ACB HEAT SPEEDAFTER NORMAL DELAY (fan remains energized)
BOARDS 24L85, 56L83 AND 97L48:SYSTEM FAN SWITCHES TO
LOW SPEED AFTER NORMAL DELAY.(fan remains energized)
Page 40
VIII−Troubleshooting−SureLight Control
PROBLEM: 1 UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE
Condition Possible Cause Corrective Action / Comments
1.1
− Both diagnostic lights fail to light up.
1.1.1
Main voltage 120V not supplied tounit.
ACTION 1 − Check 120V main voltage.Determine cause of main power failure.
LED#1−OffLED#2−Off
1.1.2
Miswiring of furnace or improperconnections.
ACTION 1 − Check for correct wiring of 120V topower make up box and transformer.ACTION 2 − Check 24V wiring to control board.
1.1.3
Circuit breaker tripped or fails toclose.
ACTION 1 − Replace circuit breaker if it is resetbut does not have continuity.ACTION 2 − If circuit breaker still trips, check forshort.
1.1.4
Door interlock switch failure.
ACTION 1 − Check that door switch is activatedwhen door is closed.ACTION 2 − Check wire connections to switch, re-place loose connectors.ACTION 3 − Check continuity of switch in closedposition. Replace if malfunctioning
1.1.5
Transformer Failure.
ACTION 1 − Check that transformer output is24V. Replace if malfunctioning
1.1.6
Failed control board.
ACTION 1 − If all the above items have beenchecked, replace board.
1.2
− Diagnostic lights flash the roll−out
code.
1.2.1
Roll−out switch open.
ACTION 1 − Manually reset the roll−out switchby pushing the top button.ACTION 2 − Determine the cause of the roll−outswitch activation before leaving furnace.code.
LED#1 O
1.2.2
Roll−out switch failure.
ACTION 1 − Check continuity across roll−outswitch. Replace roll−out switch if switch is resetbut does not have continuity.
LED#1−On,
LED#2−Slow Flash1.2.3
Mis iring or improper connections at ACTION 1 − Check wiring connections to switchLED#2 Slow FlashMiswiring or improper connections atroll−out switch.
ACTION 1 − Check wiring connections to switch.
1.2.4
Nine pin connector failure
ACTION 1 − Check 9−pin connector for properconnection to control board.ACTION 2 − Check continuity of the multi plugpin.
1.3
− On initial power−up the comb. airblower does not energize.blower does not energize. − Diagnostic lights flash the reversepolarity code.
1.3.1
120V main power polarity reversed.
ACTION 1 − Check the 120V has line and neutralcorrectly input into control.ACTION 2 − Reverse the line and neutral at the120V field connection.
LED#1−Fast Flash,LED#2−Slow Flash.
120V field connection.
1.4
− On initial power up the combustionair blower does not energize. − Diagnostic lights flash normal poweron operation.
1.4.1
Open combustion air blower motorcircuit.
ACTION 1 − Check for 120V to combustion airblower. If no power, check wire and connec-tions.
on operation.
LED#1−Slow FlashLED#2−Slow Flash
1.4.2
Failed combustion air blower motor.
ACTION 1 − If power is present at blower, replaceblower.
Page 41
PROBLEM 1: UNIT FAILS TO OPERATE IN THE COOLING, HEATING, OR CONTINUOUS FAN MODE
Condition Possible Cause Corrective Action / Comments
1.5
− On initial power−up the combustionair blower remains energized.
Di ti li ht fl h th i
1.5.1
Improper ground to the unit.
ACTION 1 − Check that the unit is properlygrounded.ACTION 2 − Install a proper main ground to theunitg
− Diagnostic lights flash the impropermain ground.
1.5.2
6−Pin connector is improperly at-tached to the circuit board.
ACTION 1 − Check 6−pin connector for properinstallation. Correctly insert connector into con-trol.
LED#1−Alternating Fast FlashLED#2−Alternating Fast Flash
1.5.3
Line voltage is below 75V.
ACTION 1 − Check that the line voltage is above75V. Determine cause of voltage drop and sup-ply correct voltage to the control.
PROBLEM 2: UNIT FAILS TO OPERATE IN THE COOLING OR HEATING MODE, BUT COMBUS-TION AIR BLOWER OPERATES CONTINUOUS. UNITS WITH CONTROL BOARDS DATE CODEDAFTER NOV.1 1997, WILL OPERATE IN COOLING WITH COMBUSTION AIR BLOWER CYCLING
5 SECONDS ON 55 SECONDS OFF, BUT NOT IN THE HEATING MODE.
Condition Possible Cause Corrective Action / Comments
2.1
− On initial power−up the combustionair blower remains energized. − Diagnostic lights flash the impropermain ground. − Units with control boards datecoded after Nov 1 1997; combustion
2.1.1
Open ignitor circuit.
ACTION 1 − Check for correct wiring and looseconnections in the ignitor circuit. Check multi −plug connections for correct installation.
coded after Nov.1 1997; combustionair blower will cycle 5 seconds on 55seconds off.
LED#1−Alternating Fast FlashLED#2−Alternating Fast Flash
2.1.2
Broken or failed ignitor.
ACTION 1 − Unplug ignitor and read resistanceacross ignitor. If resistance does not read be-tween 10.9 and 19.7 ohms, replace the ignitor.
PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOESNOT ENERGIZE
Condition Possible Cause Corrective Action / Comments
3.1
− Unit operates with a cooling or con-tinuous fan demand. − Combustion air blower will not startwith a Heating demand. − Diagnostic lights flash the limit failure
d
3.1.1
Primary or secondary (if equipped)limit open.
ACTION 1 − Check continuity across switch(es).Switches reset automatically upon cool down.ACTION 2 − Check for restrictions on blower inletair (including filter) and outlet air. Determinecause for limit activation before placing unit backin operation.
g gmode.
LED#1−Slow Flash,LED#2−On
3.1.2
Miswiring of furnace or improper con-nections at limit switch(es).
ACTION 1 − Check for correct wiring and looseconnections. Correct wiring and/or replace anyloose connections.
3.2
− Unit operates with a cooling and con-tinuous fan demand. − Combustion air blower will not startwith a Heating demand. − Diagnostic lights flash the pressure
3.2.1
Miswiring of furnace or improper con-nections to combustion air blower.
ACTION 1 − Check for correct wiring and looseconnections. Correct wiring and/or replace anyloose connections.
− Diagnostic lights flash the pressureswitch failure code.
LED#1−Off,LED#2−Slow Flash
3.2.2
Pressure switch stuck closed.
ACTION 1 − Check that the pressure switch isopen without the combustion air blower operat-ing. Replace if malfunctioning
Page 42
PROBLEM 3: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER DOESNOT ENERGIZE (CONT.).
Condition Possible Cause Corrective Action/Comments
3.3
− Unit operates with a cooling and con-tinuous fan demand. − Combustion air blower will not startwith a Heating demand. − Diagnostic lights flash the pressureswitch failure code 2 5 minutes after
3.3.1
Miswiring of furnace or improper con-nections to combustion air blower.
ACTION 1 − Check for correct wiring and looseconnections. Correct wiring and/or replace anyloose connections.
switch failure code 2.5 minutes afterheating demand.
LED#1−Off, LED#2−Slow Flash
3.3.2
Combustion air blower failure.
ACTION 1 − If there is 120V to combustion airblower and it does not operate, replace combus-tion air blower.
PROBLEM 4: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER ENERGIZES, IGNITOR IS NOT ENERGIZED.
Condition Possible Cause Corrective Action/Comments
4.1
− Unit operates with a cooling andcontinuous fan demand. − Combustion air blower energizeswith a heating demand
4.1.1
Pressure switch does not close dueto incorrect routing of the pressure
switch tubing.
ACTION 1 − Check that the pressure switch tub-ing is correctly routed. Correctly route pressureswitch tubing.
with a heating demand. − Diagnostic lights flash the pressureswitch failure code 2.5 minutes afterheating demand.
4.1.2
Pressure switch does not close dueto obstructions in the pressure tub-
ing.
ACTION 1 − Remove any obstructions from thepressure tubing and/or taps.
LED#1−OffLED#2−Slow Flash
4.1.3
Pressure switch tubing damaged
ACTION 1 − Check pressure switch tubing forleaks. Replace any broken tubing.
LED#2 Slow Flash
4.1.4
Pressure switch does not close dueto a low differential pressure across
the pressure switch.
ACTION 1 − Check the differential pressure
across the pressure switch. This pressure
should exceed the set point listed on the
switch.
ACTION 2 − Check for restricted inlet and ex-
haust vent. Remove all blockage.
ACTION 3 − Check for proper vent sizing and
run length. See installation instructions.
ACTION 4 − Check voltage to combustion air
blower.
4.1.5
Wrong pressure switch installed inthe unit, or pressure switch is out of
calibration.
ACTION 1 − Check that the proper pressureswitch is installed in the unit. Replace pressureswitch if necessary.
4.1.6
Miswiring of furnace or improper con-nections at pressure switch.
ACTION 1 − Check for correct wiring and looseconnections. Correct wiring and/or replace anyloose connections.
4.1.7
Pressure switch failure.
ACTION 1 − If all the above modes of failure havebeen checked, the pressure switch may havefailed. Replace pressure switch and determine ifunit will operate.
Page 43
PROBLEM 5: UNIT FAILS TO FIRE IN THE HEATING MODE, COMBUSTION AIR BLOWER ENERGIZES, IGNITOR IS ENERGIZED. (CONT.)
Condition Possible Cause Corrective Action/Comments
5.1
− Unit operates with a cooling and
continuous fan demand.
Combustion air blower energizes
5.1.1
Check that gas is being supplied tothe unit.
ACTION 1 − Check line pressure at the gasvalve. Pressure should not exceed 13" WC forboth natural and propane. Line pressure shouldread a minimum 4.5" WC for natural and 8.0"WCfor propane.
− Combustion air blower energizes
with Heating demand.
− Ignitor is energized but unit fails to
light.
5.1.2
Miswiring of gas valve or loose con-nections at multi−pin control amp
plugs or valve.
ACTION 1 − Check for correct wiring and looseconnections. Correct wiring and/or replace anyloose connections.
LED#1−Alternating Slow Flash
LED#2−Alternating Slow Flash
5.1.3
Malfunctioning gas valve or ignitioncontrol.
ACTION 1 − Check that 24V is supplied to thegas valve approximately 35 seconds after heatdemand is initiated.ACTION 2 − Replace the valve if 24V is suppliedbut valve does not open (check for excessivegas line pressure before replacing gas valve).ACTION 3 − Replace the control board if 24V isnot supplied to valve.
PROBLEM 6: BURNERS LIGHT WITH A HEATING DEMAND BUT UNIT SHUTS DOWN PREMATURELY
Condition Possible Cause Corrective Action/Comments
6.1
− Burners fire with a heating de-mand. − Burners light but unit shuts off priorto satisfying T−stat demand. − Diagnostic lights flash the pressureswitch code.
LED#1−OffLED#2−Slow Flash
6.1.1
Low pressure differential at the pres-sure switch.
ACTION 1 − Check for restricted vent inlet or ex-haust. Remove all blockage.ACTION 2: Check for proper vent sizing. Seeinstallation instructions.
6.2
− Combustion air blower energizeswith a heating demand.
B li ht b t f il t t lit
6.2.1
Sensor or sense wire is improperlyinstalled.
ACTION 1 − Check that sensor is properly lo-cated (page 10) and that the sense wire isproperly attached to both the sensor and thecontrol.
− Burners light but fail to stay lit. − After 5 tries the control diagnosticsflash the watchguard burners failed toignite code.
6.2.2
Sensor or sense wire is broken.
ACTION 1 − Check for a broken sensor.ACTION 2 − Test continuity across the sensewire. If wire or sensor are damaged replacethe component.ignite code.
LED#1−Alternating Slow FlashLED#2−Alternating Slow Flash
6.2.3
Sensor or sensor wire is grounded tothe unit.
ACTION 1 − Check for resistance between thesensor rod and the unit ground.ACTION 2 − Check for resistance between thesensor wire and the unit ground.ACTION 3 − Correct any shorts found in circuit.
6.2.4
Control does not sense flame.
ACTION 1 − Check the microamp signal fromthe burner flame. If the microamp signal is be-low 0.70 microamps, check the sense rod forproper location or contamination.ACTION 2 − Replace, clean, or relocate flamesense rod. If rod is to be cleaned, use steelwool or replace sensor. DO NOT CLEAN RODWITH SAND PAPER. SAND PAPER WILLCONTRIBUTE TO THE CONTAMINATIONPROBLEM. NOTE: Do not attempt to bendsense rod.
Page 44
PROBLEM 6: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN PREMATURELY (CONT.)
Condition Possible Cause Corrective Action/Comments
6.3
− Combustion air blower energizeswith a heating demand. − Burners light. − Roll−out switch trips during theheating demand. − Diagnostic lights flash roll−out fail-ure.
6.3.1
Unit is firing above 100% of thenameplate input.
ACTION 1 − Check that the manifold pressurematches value listed on nameplate. See installa-tion instructions for proper procedure.ACTION 2 − Verify that the installed orifice sizematch the size listed on the nameplate or instal-lation instructions.ACTION 3 − Check gas valve sensing hose to in-sure no leaks are present.ACTION 4 − Check the input rate to verify ratematches value listed on nameplate.ure.
LED#1−OnLED#2−Slow Flash
6.3.2
Gas orifices leak at the manifold con-nection.
ACTION 1 − Tighten orifice until leak is sealed.NOTE: Be careful not to strip orifice threads. AC-TION 2 − Check for gas leakage at the threadedorifice connection. Use approved method forleak detection (see unit instructions).
6.3.3
Insufficient flow through the heat ex-changer caused by a sooted or re-
stricted heat exchanger.
ACTION 1 − Check for sooting deposits or otherrestrictions in the heat exchanger assembly.Clean assembly as outlined in instruction manu-al.ACTION 2 − For 80MGF gas furnaces, check forproper combustion and flow. CO2 should mea-sure between 6.0% and 8.0% for natural and6.5% and 8.5% for L.P. CO should measure be-low .04% (400PPM) in an air−free sample of fluegases.
6.3.4
Burners are not properly located inthe burner box.
ACTION 1 − Check that the burners are firing intothe center of the heat exchanger openings. Cor-rect the location of the burners if necessary.
6.4
− Combustion air blower energizeswith a heating demand. − Burners light roughly and the unitfails to stay lit. − Diagnostic lights flash watchguardflame failure.
6.4.1
Recirculation of flue gases. This con-dition causes rough ignitions and op-eration. Problem is characterized by
nuisance flame failures.
ACTION 1 − Check for proper flow of exhaustgases away from intake vent. Remove any ob-stacles in front of the intake and exhaust ventwhich would cause recirculation.ACTION 2 − Check for correct intake and ex-haust vent installation. See instructions
flame failure.
LED#1−Alternating Slow FlashLED#2−Alternating Slow Flash
6.4.2
Improper burner cross−overs
ACTION 1 − Remove burner and inspect thecross−overs for burrs, or any restriction or ifcrossover is warped. Remove restriction or re-place burners.
Page 45
PROBLEM 6: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN PREMATURELY (CONT.)
6.5
− Combustion air blower energizeswith a heating demand. − Burners light. − Diagnostic lights flash watch guardflame failure. − NOTE" Unit might go into 60 min-ute Watchguard mode depending onintermittent nature of sensor signal.
LED#1−Alternating Slow FlashLED#2−Alternating Slow Flash
6.5.1
Loose sensor wire connectioncauses intermittent loss of flame sig-
nal.
ACTION 1 − Check that the sensor is properly lo-cated.ACTION 2 − Check that the sense wire is proper-ly attached to both the sensor and the control.Pay extra attention to the pin connectors.
PROBLEM 7: CONTROL SIGNALS LOW FLAME SENSE DURING HEATING MODE
Condition Possible Cause Corrective Action/Comments
7.0
− Unit operates correctly but thediagnostic lights flash low flamesense code
7.1.1
Sense rod is improperly located onthe burner.
ACTION 1 − Check the sense rod for proper loca-tion on the burner. Properly locate the sense rodor replace if rod cannot be located correctly.
sense code.
LED#1−Slow FlashLED#2−Fast Flash
7.1.2
Sense rod is contaminated.
ACTION 1 − Check sense rod for contaminationor coated surface. Clean the sense rod with steelwool or replace sensor. DO NOT USE SAND PA-PER TO CLEAN ROD. SAND PAPER WILLCONTRIBUTE TO THE CONTAMINATIONPROBLEM.
PROBLEM 8: INDOOR BLOWER FAILS TO OPERATE IN COOLING, HEATING, OR CONTINUOUSFAN MODE
Condition Possible Cause Corrective Action/Comments
8.0
− Indoor blower fails to operate incontinuous fan, cooling, or heatingmode.
8.1.1
Miswiring of furnace or improper con-nections at control or indoor blower
motor.
ACTION 1− Correct wiring and/or replace anyloose connections. Check for correct wiring andloose connections.
8.1.2
120V is not being supplied to the in-door air blower or blower motor fail-
ure.
ACTION 1 − Check for 120V at the various callsfor indoor blower by energizing "Y", "G", and "W"individually on the low voltage terminal strip.Note that when "W’ is energized, the blower isdelayed 45 seconds. If there is 120V to each mo-tor tap but the blower does not operate, replacethe motor.
8.1.3
Defective control board
ACTION 1 − If there is not 120V when "Y", "G", or"W" is energized, replace the control.
PROBLEM 9: RF STATIC DURING TIME FOR IGNITION
Condition Possible Cause Corrective Action/Comments
9.0− AM radio interference
9.1.2Ignitor operation
ACTION 1− Call Technical Support, Dallas
Page 46
SERVICE NOTES