Scania Heating & Ventilation

7/24/2019 Scania Heating & Ventilation

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Heating, Ventilation and AC

Function description

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18:03-53Issue 1 en

Scania CV AB 1999-08, Sweden


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2 Scania CV AB 1999, Sweden 1800c32b.mkr

Contents

Function description General............................................................ 3

Controls........................................................... 5

Heating system................................................ 7

AC system..................................................... 18

Ventilation system ........................................ 29

Stationary supply system .............................. 31

Contents


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1870f15b.mkr Scania CV AB 1999, Sweden 3

Function description

General

The climate control system in the Omnicity isdivided into two to four sub-systems which canbe adapted to each customers individual needsand wishes, depending on the option selected.The sub-systems are controlled by a softwaremodule in the bus BNS system (multiplexsystem), from now on called the climatecontrol module.

When a passenger area temperature has beenset, the climate system tries to achieve thistemperature by controlling the different sub-

systems, i. e. heating, ventilation and AC,(air conditioning).

General


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4 Scania CV AB 1999, Sweden 1870f15b.mkr

Component location

1 Roof unit, in the case of AC, the units arereplaced by an AC unit

2 Heating element, passenger area

3 Door fan

4 Driver area fan with heating element

5 Auxiliary heater

6 Connection unit, supply station

7 Circulation pump

8 Heat exchanger (optional)

9 Water filter

10 Heating element, driver area

11Defroster unit

12 Feed pump

General


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Controls

All the climate controls are located on a panelon the right side of the driver area.

1 Fan speed, defroster

2 Temperature setting, defroster

3 Timer for auxiliary heater, refer to separatedescription.

4 Temperature setting, driver area

5 Temperature setting, passenger area

6 Heating fan, driver area

7 Air dehydration

8 Recirculation of ventilation air

9 Pause period heating

10 Floor heating at the entrance to the bus

Controls


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Heating system

Design

Schematic diagram of the Heating system

1 Engine

2 Feed pump

3 Coarse filter for impurities

4 Central distribution unit

5 Auxiliary heater

6 Driver area heating

7 Passenger area heating

8 Defroster unit

9 Roof unit

The engine coolant, (1), is used as the primaryheat source. The engine coolant is fed by afeed pump, (2), through a course filter, (3), tothe heating system central distribution unit,

(4), which is located at the front of the bus. Inthe central distribution unit, the heat isdistributed by way of an auxiliary heater, (5),to the different sub-systems; driver areaheating, (6), passenger area heating, heatingelement circuit, (7), defroster unit, (8), andpassenger area heating, roof unit (9).

2-axle buses are equipped with 5 temperaturesensors recording outdoor temperature, airduct temperature and passenger areatemperature. 3-axle buses are equipped with 7

temperature sensors. The temperature sensorsare common to the entire climate system andare used by the climate control module tocontrol the heating and ventilation system.

Heating system


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Feed pump

The feed pump is used to ensure sufficient flowand therefore an even distribution of heat to allcircuits in the system.

There are two pump designs:

The U4814 is used in two-axle buses

The U4851 is used in articulated buses(earlier bus models were equipped with theU4816)

The U4814 (and the 4816) has an electric motorwith brushes whereas the U4851 has an electricmotor without brushes.

When the engine is running, the feed pumpstarts if:

the climate control module requests such alarge quantity of heat that the flow from theengine cooling system is not sufficient

the auxiliary heater is running.

The feed pump is shut off after some delay whenthe above criteria are not met.

Note: If the feed pump, U4851, is startedwithout water, it will surge and automatically beshut down. It cannot be restarted until after 10minutes.

Feed pump

Heating system


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Water filter

The principal task of the water filter is to preventcoarse particles from entering the variouscomponents of the heating system. The waterfilter is available in two versions.

On old bus models the water filter, (3), is locatedin the central distribution unit between two ballvalves, (1) and (2).

1 Ball valve

2 Ball valve

3 Water filter

1 2

3 103

920

On later models, the water filter and the shutoffvalve have been integrated into one unit, located

to the rear, in the engine compartment.

Heating system


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Central distribution unit

The design of the central distribution unitvaries depending on the selection made, butthe choice of components and positioning arebasically the same regardless of theconfiguration. A bypass line is connected

between the central distribution unit, outlet(7) and inlet (2), when no auxiliary heater isinstalled.

Central distribution unit type B can be foundon buses with roof unit and heating element

Central distribution units type C (modelEK100E) and type F (model EK100) are usedon buses with roof unit, heating element and

supply station connection.

Central distribution unit type E can be foundon buses with a roof unit

Central distribution units type G are used onbuses with roof unit, heating element andsupply station connection type Hansen.

1 To driver area circuit

2 From auxiliary heater

3 To passenger area circuit heating element

4 From passenger area circuit heatingelement

5 To defroster and roof circuit

6 From engine7 To auxiliary heater

Heating system


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1 Junction box EK100E

2 ON/OFF valve

3 Circulation pump

4 Heat exchanger P30

5 To roof units

6 From engine

7 To driver area fan

8 To passenger area circuit

9 From passenger area circuit

10 From auxiliary heater

11 ON/OFF valve

12 Water filter

13 To auxiliary heater

Line to auxiliary heater and roof

Water is led from the engine, (6), into thecentral distribution unit by way of a waterfilter, (12), and a shutoff valve. The water isthen led to the auxiliary heater, (13), and backto the central distribution unit by way of inlet(10). Water is distributed to the roof units bayway of connection (5).

Control of driver area circuit

A pneumatic ON/OFF valve (11) controls theheat transfer to the driver area heating elementand the driver area fan (7).

Control of passenger area circuit

A pneumatic ON/OFF valve (2) controls theheat transfer to the passenger area heatingelement. The circulation pump, (3), maintainsa flow to the passenger area circuit, (8), andback to the central distribution unit by way ofinlet (9).

Adaptation to supply station, EK100E

There are three different alternatives foradapting the bus to supply station. In thisalternative the central distribution unit is

equipped with junction box EK100E 1 andheat exchanger P30 4.

Adaptation to supply station, EK100

The same as above but junction box (1) hasbeen replaced by a version without integratedelectrical connection.

Adaptation to supply station, heatexchanger on supply station

In this case the heat exchanger is located inthe heat supply station. The centraldistribution unit only houses separateconnections for compressed air and wateralong with a check valve.

Heating system


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Auxiliary heater

Webasto

Stroco

The auxiliary heater may be of the dieselfuelled type, refer to illustration, the ethanolfuelled type or the combination type (electrical

& diesel fuelled or electrical & ethanolfuelled). The auxiliary heater is intended toprovide additional heat for the heating systemwhen the bus is parked. The function variesdepending on the model.

Start/switch off is controlled in the followingways:

The heater is started and shut off by meansof the timer manual start/stop button or bymeans of programmed start/stop times,refer to supplier's instructions.

In operation, the water temperature in theheater is adjusted to a specific level by anintegral control unit with an temperaturesensor.

When the auxiliary heater is running, theclimate control module is influenced asfollows:

When the engine is running, the feed pump

cannot be shut down.

When parked, the climate control modulestarts the feed pump and opens the valvesto the passenger area heating, the heatingelement and the driver area heating.

When the auxiliary heater is running, it tries tomaintain a specific water temperature. Thetemperature is controlled by an integralthermostat which starts or stops the burner.

The auxiliary heater is shut off manually by thedriver or by the timer, after having operated forup to two hours, depending on the time set.

Heating system


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Driver heating

1 ON/OFF valve

2 Heating fan3 Heating element

4 Temperature sensor

Driver area fan with integral heating element

The driver area heating is designed as a circuit,see illustration. The heat transfer to the circuitis regulated by a pneumatic ON/OFF valve, (1),

located on the central distribution unit. Thevalve is controlled by the climate controlmodule. The circuit includes a speciallyadapted heating fan, (2), fitted at the front ofthe bus and an optional heating element, (3).The fan must also heat the driver and improvethe defroster function. The temperature in thedriver area is registered by a temperaturesensor, (4).

The control of heat for the driver area fan and

heating element (if fitted) starts when thepotentiometer for driver area temperaturesetting has been turned from its OFF position.The fan starts when the climate control modulerequires an additional quantity of heat in orderto maintain the set driver area temperature. Thedriver can switch the fan off manually.

When the engine is running, the valve and fanare controlled by the climate control module.The driver can do the following manually:

Switch off the fan.

Change the temperature setting.

Regulate the air quantity and directionusing the air vent in the driver area.

If the temperature sensor is affected by an opencircuit or short circuit, the climate controlmodule records this and responds by regulatingthe valve at fixed intervals according to theposition of the potentiometer.

Heating system


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Passenger area heating, heatingelement

1 ON/OFF valve

2 Circulation pump

3 Heating element

4 Heating fan

5 Temperature sensor

The primary source of heating for the buspassenger area is the heating element, see

illustration. The central distribution unit housesa pneumatic ON/OFF valve, (1), and acirculation pump, (2). The heat-emittingcomponents in the circuit are the heatingelement, (3), and the heating fans, (4). Thetemperature is recorded by a temperaturesensor, (5).

On articulated buses, there are two separatetemperature sensors, one for the front sectionof the bus and one for the rear. The heating fansin the front and rear sections are also separately

controlled.

The climate control module starts controllingthe heat for the heating element circuit whenthe potentiometer for passenger areatemperature setting has been turned from itsOFF position and the recorded temperature islower than the set temperature. On start-up, thecirculation pump on the central distributionunit also starts. The heating fans also startwhen the climate control module receivesinformation that the water temperature ishigher than approximately 43C.

When the engine is running, the circulationpump, (2), runs continuously and the ON/OFFvalve, (1), on the central distribution unitopens/closes depending on the calculated heatneeded. When the ON/OFF valve opens, hotwater is led from the engine and the auxiliaryheater into the heating element circuit and partof the water is returned to the engine at theother end of the circuit. When the ON/OFF

valve is closed, the water in the circuitcirculates continuously since the circulationpump, (2), is running. The passenger areatemperature is adjusted by means of apotentiometer in the driver area.

The climate control module stops regulatingthe heat to the heating elements when thetemperature exceeds the set value and theclimate control module has not opened thevalve for 13 minutes or if the potentiometer forpassenger area temperature has been turned to

OFF position.

When receiving a faulty value from thepassenger area temperature sensor, as causedby open circuit or short, the climate controlmodule regulates according to the AC system

values, refer to AC system - Fault control.

Heating system


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Passenger heating, roof

1 Double radial fan

2 Water valve

3 Heat exchanger

4 Filter

The roof heating function is integrated into twoof the bus roof units for ventilation, or into theAC unit, if fitted. The roof unit consist of the

following components:

Double radial fan

Heat exchanger

Pneumatically controlled water valve, typeON-OFF

Pneumatically controlled flap for selectingfresh air or recirculated air

Filter Pneumatic valve for flap and water valve

Heating system


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The regulation starts when the engine starts andthe potentiometer for adjustment of passengerarea temperature has been turned from its OFFposition.

When the engine is running, the climate controlmodule controls the valves to the roof unit sothat the temperature in the air ducts is the sameas the set passenger temperature.

The climate control module moves the flaps tothe recirculation position:

when the AC unit is running and theoutdoor temperature is higher than thepassenger area temperature, which at thesame time exceeds the set value by morethan 4 C.

or when the quantity of heat in the enginecooling system is not sufficient to achievethe desired temperature, e. g. at extremelylow outdoor temperature or immediatelyafter the bus has started.

If the climate control module receives a faultyvalue from the air duct temperature sensor, theroof valves are controlled in relation to thecontrol of the passenger area heating elements.

Heating system


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Defroster

The defroster unit is of the "over-head" type. Itblows air from the top of the screen anddownwards. This solution gives the air flow amuch better "adhesion" against the window, i.e.

it does not "whirl" away from the windowtowards the driver.

To further increase the efficiency of thedefroster, the driver area is designed so that theinlet to the driver area fan is located at the baseof the windscreen.

The defroster fan is started manually by thedriver and the heat control of the defrostervalve starts when the driver turns thepotentiometer for temperature adjustment fromits OFF position. In this position, the climatecontrol module starts to alternately open/closethe defroster valve provided that thetemperature level of the defroster air is belowthe default value.

When the engine is running, the defroster iscontrolled in the following ways:

The temperature level of the defroster air isdetermined by the driver using apotentiometer on the control panel.

The air to the defroster is controlled by theclimate control module and can be drawneither from the outside, fresh air, or frominside the bus, recirculated air.

Recirculated air is used when the AC unitis running and the outdoor temperature ishigher than the passenger area temperature,at the same time exceeding the set value bymore than 4 C.

The amount of heat supplied to thedefroster is controlled completely by theclimate control module which regulates thevalve in the defroster unit.

The driver controls the defroster fan and itsspeed which has three different settings.

The temperature is recorded by thetemperature sensor in the defroster duct.

The driver can manually turn off the defroster

by shutting off the fan and turning thepotentiometer to its OFF position.

If the climate control module receives a faultyvalue from temperature sensor in the defrosterduct, regulation will be directly according tothe potentiometer setting.

Technical data

Heating capacity 14 kW

Air flow, maximum 1050 m/h

Nominal voltage 24 V

Heating system


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Function descriptionAC system

General

There are two basic designs of the system, onefor two-axle buses and one for articulatedbuses.

System design for two-axle bus

The AC system has three sensors, recording theoutdoor temperature, (11), the air ducttemperature, (12), and the passenger areatemperature, (13). The sensors are common tothe entire climate control system and their useis integrated with other sub-systems. The

system is controlled by the climate controlmodule.

The AC system consists of one or twocompressors, (14), with associated high-pressure switch, (1), and low-pressure switch,(9), located in the engine compartment and aroof unit, (10), located on the bus roof.

Where two compressors are used, they are runsynchronously and only one set of high-/low-pressure switches are fitted in the area of the

rear compressor.

The roof unit consists of the followingcomponents:

High-pressure switch 1 and low-pressureswitch 9.

Condenser 2

Safety valve 3

Storage tank 4, which "stores" therefrigerant when liquid.

Dehydrator/filter 5, which is used toremove impurities, moisture and acid fromthe refrigerant.

Expansion valve 6

Evaporator 7

Air flap 8 for switching between fresh airand recalculated air.

AC system


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Schematic diagram of AC system (two-axle bus)

1 High-pressure switch

2 Condenser

3 Safety valve

4 Storage tank

5 Dehydrator

6 Expansion valve

7 Evaporator8 Air flap for switching between fresh or recirculated air.

9 Low-pressure switch

10 Roof unit

11 Outdoor temperature sensor

12 Air duct temperature sensor

13 Passenger area temperature sensor

14 Compressor

AC system


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System design for articulated bus

Schematic diagram of AC system (articulated bus)

1 Outdoor temperature sensor

2 Roof unit

3 Air duct temperature sensor


5 Compressors

The AC system has two roof units (2) located onthe bus roof. In the engine compartment, thereare two compressors (5), each with two sets ofhigh-/low-pressure switches.

The AC system uses one outdoor temperaturesensor (1), two air duct temperature sensors (3),and two passenger area temperature sensors (4).The two AC units are individually controlledand thus two sets of temperature sensors arerequired. However, the sensors are common tothe entire climate system and are also used in theheating and ventilation systems.

AC system


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Component location, roof unit, AC

1 Condenser

2 Filter, fresh-air side

3 Air flap for switching between fresh or recirculated air

4 Axial fans

5 Double radial fan

6 Heat exchanger for heating ventilation air

7 Heat exchanger

8 Expansion valve

9 Dehydrator

10 Storage tank

AC system


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Compressor

Articulated buses always have twocompressors. Two-axle buses normally haveone. Where two-axle buses are used in very hotclimates they are equipped with twocompressors. The compressors are located inthe engine compartment and are driven viadrive belts by the engine. Engagement anddisengagement is by means of an electro-magnetic clutch and is controlled by theclimate control module. If the refrigerantpressure is extremely high or low, the electro-magnetic clutch disengages the compressor.The compressor draws in refrigerant from theevaporator, compressing it, raising the pressure

and the temperature of the refrigerant.

Condenser

The condenser, consists of a large heatexchanger and a number of axial fans forcooling the hot refrigerant using fresh air.When heat is extracted, the refrigeranttransforms from gas into liquid, which is called

condensation.

Storage tank

The storage tank holds sufficient refrigerant inits liquid state.

Dehydrator

The dehydrator/filter is used to removeimpurities, moisture and acid from therefrigerant. The filter must be renewed at

regular intervals to prevent damage to othercomponents.

Expansion valve

The expansion valves on the right and left sidesregulate the refrigerant quantity passed on tothe evaporator. The expansion valve, in turn, iscontrolled partly by the evaporator outlettemperature and partly by the system pressure.The pressure and temperature of the refrigerant

drops after the expansion valve.

AC system


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Air flap for fresh air/recirculatedair

To control what type of air shall be blown on tothe evaporator, an air flap for fresh/recirculated

air is fitted in the AC unit. The flap iscontrolled electrically by the climate control

module.

Evaporator

The evaporator consists of two heat exchangerswith two radial fans each. The fans arecontrolled by the climate control module atthree different settings. At the lowest setting,only one fan per heat exchanger is running,

operating at approximately 12 V. At mediumsetting, all four fans run, operating at approx.20 V. At the highest setting, the fans operate atapproximately 24 V.

Fresh or recirculated air is blown into theevaporator through the heat exchanger and outinto the bus air ducts. Heat is drawn from theair passing through and is absorbed by therefrigerant, which is transformed from liquid togas, which is called evaporation.

The evaporator assembly also comprises a heatexchanger, which is connected to the heatingsystem. This makes it possible to use the ACunit for heating the ventilation air, refer toHeating system.

To avoid ice forming in the evaporatorassembly, there is an ice switch. The ice switchcuts out when temperature is too low,disengaging the compressor.

Filter

The AC unit is equipped with two differentfilters. One is located on the recirculated air

side and the other on the fresh air side, .

AC system


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Temperature sensors

Outdoor temperature sensor

The outdoor temperature sensor is located at thefront on the left-hand side and records the

outdoor temperature. This is necessary in orderto avoid the climate control module starting theAC unit in cold weather, i.e. when the outdoortemperature is below 8C.

Air duct temperature sensor

The air duct temperature sensors are located inthe roof ducts below the air filters of the roofunits. The sensors are used when the AC systemworks with dehydration and heat must be addedto keep the temperature in the air ducts at thesame level as that set for the passenger area.

Passenger area temperature sensor

The passenger area temperature sensor islocated opposite the left-hand roof unit andrecords the temperature as a reference for theclimate control module. There is also atemperature sensor in the driver area, fittedbelow the instrument panel.

AC system


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Refrigeration process

The AC unit, in principle, operates as follows:

1 The compressors raise the pressure andtemperature of the refrigerant.

2 In the condenser, heat from the refrigerantis released and the gas condenses, i.e. itchanges to liquid state.

3 The storage tank hold sufficient refrigerantto meet the evaporator requirements.

4 The dehydrator removes moisture and anyimpurities from the refrigerant.

5 The expansion valves separate therefrigerant high-pressure side from its low-

pressure side.

6 Heat from the air passing through is addedto the cold refrigerant in the evaporators.The refrigerant changes to gas state(evaporates).

7 The cycle is completed when therefrigerant reaches the compressor again.

Start

The AC unit starts when the climate controlmodule requests low temperature, i.e. when thetemperature in the passenger area exceeds theset temperature by more than 2 C. This occursprovided:

the outdoor temperature exceeds 8 C

approximately 1 minute has passed sincethe engine was started

the battery voltage exceeds 21 V.

Operation

When the AC unit is running it is entirelycontrolled by the climate control module,which alternately engages and disengages thecompressor. When the AC unit cannot maintainthe requested temperature and the passengerarea temperature sensor records a temperaturelevel of approx. 3 C above the set temperature,the fans are started at maximum speed.

In the control of the fresh/recirculated air flap,the climate control system selects flap positionaccording to which of the outdoor temperatureand passenger area temperature is lower. If it iscolder outside than inside the flap is in fresh-airposition. Otherwise, the flap is set to the

recirculation position, and air from thepassenger area is blown to the evaporator andout into the air ducts. The driver can manually

set the flap to the recirculation position.

AC system


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Shutdown

The AC unit is shut down:

when the passenger area temperature isbelow the set level

in the event of abnormally high or low gaspressure. The AC unit starts again when thepressure levels in the system are normal

when the temperature is low at theevaporator and ice may form. The AC unitstarts again after approx. 30 seconds whenthere is no longer any risk of ice forming

if the battery voltage is lower than 21 V.

Fault control

When receiving a faulty value from thepassenger area temperature sensor, as causedby an open circuit or short, the climate controlmodule regulates according to thepotentiometer temperature level setting asfollows:

< 21C = AC activated

21 - 23C = Ventilation activated

24C = 1/3 heat on

26C = 2/3 heat on

28C = 3/3 heat on

If a faulty value is received from thepotentiometer, the climate control moduleadjusts to the default value, 21C.

Note: On articulated buses there are twotemperature sensors located in the passengerarea. If a temperature sensor fails, the climatecontrol module adjusts to the temperaturerecorded by the other temperature sensor. Incase both temperature sensors fail, adjustmentis as above.

In case of too high or too low pressure at thecompressor, the high-pressure switch or thelow-pressure switch, respectively, cuts out

immediately, disengaging the compressor,according to the following:

The high-pressure switch cuts at 22.5 barand is reset when the pressure has droppedto 15.5 bar.

The low-pressure switch cuts at 0.2 bar andis reset when the pressure has risen to 1.9bar.

After a delay of approx. 3 minutes, when thepressure is stabilised, the compressor is re-engaged. If the high- or low-pressure failurepersists, the compressor is disengaged in thesame way. If this is repeated after five startingattempts, the AC function will be completelyblocked and service will be required before itcan be used.

When the temperature at the evaporator isbelow -0,8 C, the ice switch cuts out and thecompressor is disengaged. After a delay ofapprox. 30 seconds, when the temperature hasexceeded +2,5 C, the compressor is engagedagain.

AC system


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Air dehydration

When the climate is in the transition zonebetween cold and hot, neither the AC systemnor the heating system operates. In this case,the AC systems so-called air dehydration is

used to dehydrate the air if the humidity of theair outside the vehicle is high. To sum up, theclimate control module requests lowtemperature or high temperature so as toachieve the temperature set for the passengerarea also in the air duct and so as to removemoisture from the air by way of the AC unit.

Air dehydration is activated using the switch inthe driver area. Starting and blocking of the ACunit works in the way described under AC unit

start.During air dehydration the AC unit runs withthe evaporator fans at speed setting 2. Theclimate control module adjusts the air ducttemperature so that it equals the set value. Theflaps automatically move to the recirculationposition.

Air dehydration automatically switches off

10 minutes after activation.

Technical data

Heating capacity (heater) 40 kW

Cooling capacity(evaporator)

22 kW

Air flow, maximum 3600 m/h

Nominal voltage 24 V

Refrigerant R134 a, free fromCFC

Weight of AC unit approx. 175 kg

AC system


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Scania CV AB 1999, Sweden


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Function descriptionVentilation system

General

Schematic diagram of the Ventilation system

1 Defroster unit

2 Roof unit

In principle, the ventilation system mustensure:

a supply of fresh air to the bus through thedefroster unit, (1), and roof unit orAC unit, (2).

an increase in air quality by filteringincoming air and expelling old air.

This is done by continuously maintaining anoverpressure inside the bus in order to prevent,in winter, rushes of cold air from the doors (orfrom the articulated section in an articulatedbus) and to prevent, in summer, road dust fromentering the passenger area.

The ventilation fans are located in the roof unit.Fresh air and/or recirculated air blows throughthe ventilation ducts of the bus and out into thepassenger area by way of slots along the sidewindows, the air being led down the windows.

On models with AC, the AC unit evaporatorfans are used as ventilation fans. They will addfresh air or recirculate passenger area airdepending on the positions of the ventilationflaps. The air is heated or cooled in the AC unitand blown out through the bus ventilationducts.

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Start/shutdown

The ventilation system is integrated with otherclimate control components and, in principle, isstarted and switched off when the engine isstarted and switched off.

Operation

Air flap for recirculated air and fresh air:

Moves from fresh air to recirculated airwhen the outdoor temperature is 4C abovethe set temperature.

Moves from fresh air to recirculated airwhen the roof valve is continuously open.

This indicates that the outside temperatureis so low that there is not sufficient heat towarm up the incoming air to the settemperature.

Can be moved manually from fresh air torecirculated air position by means of aswitch on the control panel next to thedriver.

Fresh air fans:

Fan speed I is always active.

Fan speed II is activated when thepassenger area temperature exceeds the settemperature by more than 1.5 C.

Fan speed III is activated when thepassenger area temperature exceeds the settemperature by more than approx. 3 C.

Ventilation system


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Stationary supply system

General

The stationary supply system fulfils the busrequirements for heating and compressed airwhen it is parked. In addition, the system shall,if required, supply the bus with voltage forcharging batteries and operating the feed pump.

The design of the system will depend on thedesign of the supply station. Two differentsystems are available:

Supply station with heat exchanger in thebus and unit connection, EK

Supply station with heat exchanger, controlsystem and pump outside the bus andseparate connections.

The two different connection systems are:

Unit connection, type EK100 with water,air and EK100E, which also has anelectrical connection assembled in oneblock

Separate connection, type Hansen, withseparate water, air and electricalconnections

Example of unit connection



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Unit connection with heatexchanger in bus

Design

The connection unit EK100/EK100Eoperates as a connection point for air andwater between the bus and the supplystation. If the E variant is selected, thismeans that power for charging the batteryand for control signal, if used, can be fedvia the EK block.

The heat exchanger exchanges heat fromthe supply station to the bus internalheating system.

The circulation pump supplies a flowthrough the heating circuits and the enginewhen the bus is connected to a supplystation. The bus feed pump is used for thispurpose, see Heating system.

The temperature sensor is the same sensoras used for the driver area heating, seeHeating system.

The driver area fan with heating element isused to create an increased heat supply

when the bus is connected to a supplystation.

The control system is integrated in theclimate control module.

There is an optional 7-pin connection forbattery voltage and signals to the climatecontrol module for high and lowtemperature operation.



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Function

The system is activated when the driverconnects to the EK100 / EK100E junction box.The following occurs in the junction box:

1 The thumb grip on the junction blockpushes in the microswitch on the junctionbox.

2 The compressed air valve on the junctionbox changes position.

3 The compressed air cylinder presses in thejunction block.

4 Connections for water and compressed airopen, as does the electrical connection in

the case of the EK100E.

5 The supply station provides the bus withheating and compressed air.

6 When EK100E is used, the supply stationalso provides the bus with a chargingcurrent of maximum 15 A and a hightemperature signal.

When the supply station is connected, thefollowing occurs:

The supply station continuously suppliesthe heat exchanger with a hot water flow.

The supply station continuously suppliesthe bus with compressed air.

The supply station provides the bus with acharging current of maximum 15 A (onlyapplies to EK100E).



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Unit connection with heat exchanger in bus


2 Feed pump

3 Heat exchanger

4 Driver area circuit

5 Passenger area circuit

6 Main return line to engine

When the temperature in the passenger area,(1), has sunk below the preset value 5 - 16 C,the feed pump, (2), starts. Heat is absorbedfrom the heat exchanger, (3), and distributed

into the driver circuit, (4), and into thepassenger circuit, (5). No water flows out to theroof circuits since these valves are closed. Inthe passenger circuit, the water is distributedpartly into the normal supply via the circulationpump and partly into the normal return line. Atthe rear of the bus the water flows arecombined and continue into the main returnline down to the engine, (6).

When the temperature has risen above the setvalue, the feed pump is switched off. Theheating continues until the bus is disconnectedfrom the supply station or until the systementers high temperature position.

In the high temperature position, the referencetemperature changes from 5 - 16 C to 18 Cafter a delay of approx. 3 minutes. The feedpump is started at the same time and runscontinuously and the climate control modulestarts and shuts off the driver area fan in orderto achieve the correct temperature.

The driver switches the system off anddisconnects the bus from the supply station bypushing in the thumb grip on the junction box.The following occurs:

1 The microswitch on the junction box isinactivated.

2 The compressed air valve on the junctionbox changes position.

3 The compressed air cylinder presses outthe junction block.

4 The connections for water and compressedair are closed.

5 The charging current is cut (only applies toEK100E).



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Separate connection with heatexchanger outside the bus

Design

In this variant all components as above, see

Design of the EK system/heat exchanger in thebus, are fitted in a box on the supply station.Also available are:

Water connections by leakproof couplingsof type Hansen as installed on the centraldistribution unit.

An air connection which is located outsidethe central distribution unit.

A 3-pin electrical connection which is

located outside the central distribution unit.The terminals are for battery voltage + and- and a signal for starting the driver areafan and the door fans.

An extra check valve fitted on the centraldistribution unit. This ensures flow throughthe whole bus when it is connected to asupply station without affecting theoperation when the engine is running.

A control system for the supply station is

located on the heating supply station.



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Separate connection with heat exchanger outside the bus

1 Check valve

Operation

The system is passive and all active parts arelocated on the supply station outside the bus.

A pump located on the supply station pumpsheated water into the bus. The water isdistributed into all the open circuits, driver areaheating, passenger area heating and engine, asshown in the illustration. The check valve, (1),prevents the water from flowing directly backout to the supply station.

The door fans and driver fan can be started viaa 3-pin electrical connection.

Note: When a bus is connected to a supplystation using separate connections, it isimportant that the main current is cut,otherwise there will be no heating inside bussince all the heater valves are closed.


Scania Heating & Ventilation

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