OPERATION/SERVICE MANUAL for

OPERATION/SERVICE MANUALfor

MCC Eco Xcel SERIES

T-367 Manual

REV. 07/2015

T-367

© 2015 Mobile Climate Control

1© 2015 Mobile Climate Control T-367Rev . 07/2015

TABLE OF CONTENTS

SAFETY SUMMARY Safety--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DESCRIPTION 1--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.1 INTRODUCTION 1--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2 GENERAL DESCRIPTION 1--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.2.1 Rooftop Unit 1--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2.2 Condensing Section 1--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2.3 Evaporator Sections 1--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.2.4 MCC Microprocessor 1--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1.3 REFRIGERATION SYSTEM COMPONENT SPECIFICATIONS 1--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.4 ELECTRICAL SPECIFICATIONS -- MOTORS 1--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 SAFETY DEVICES 1--4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.6 AIR CONDITIONING REFRIGERATION CYCLE 1--5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.7 HEATING CYCLE 1--5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

OPERATION of MCC XCEL DRIVER DISPLAY 2--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.1 General Description 2--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2 STARTING, STOPPING AND OPERATING INSTRUCTIONS 2--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.2.1 Starting 2--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.3 SEQUENCE OF OPERATION 2--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.3.1 Function of Keys when “Engine On” and controller active: 2--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4 BASIC OPERATING INSTRUCTIONS 2--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.4.1 Display 2--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4.2 Interior Set Point Temperature Control 2--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4.3 Blower Speed Setting 2--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4.4 Mode Selection Descriptions 2--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4.5 Capacity Control “Ladder” Diagrams 2--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4.6 Display Settings 2--5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4.7 HVAC Information Screens 2--6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4.8 HVAC Diagnostics Screens 2--7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.4.9 HVAC Alarm Description 2--8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.5 MCC Eco NG Coolview 2--9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.5.1 Starting the MCC Coolview Application 2--10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.5.2 Coolview Screen Layout 2--11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.5.3 Eco NG Display Pin out Description 2--16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.5.4 Eco NG Controller Pin out Description 2--17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TROUBLESHOOTING 3--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.1 System Will Not Cool 3--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.2 System Runs But Has Insufficient Cooling 3--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.3 Abnormal Pressures 3--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.4 Abnormal Noise Or Vibrations 3--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.5 No Evaporator Air Flow Or Restricted Air Flow 3--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.6 Expansion Valve Malfunction 3--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.7 Heating Malfunction 3--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SERVICE 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.1 MAINTENANCE SCHEDULE 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


4.2 OPENING TOP COVER (EVAPORATORS) 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.3 REMOVING TOP COVERS (CONDENSER) 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4 SUCTION AND DISCHARGE SERVICE VALVES 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4.1 Installing R--134a Manifold Guage Set 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4.2 SYSTEM PUMP DOWN FOR LOW SIDE REPAIR 4-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4.3. Removing Entire System Charge 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.5 REFRIGERANT LEAK CHECK 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6 EVACUATION AND DEHYDRATION 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6.1 General 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6.2 Preparation 4-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6.3 Procedure for Evacuation and Dehydrating System (One Time Evacuation) 4-8. . . . . . . . . . . . . . .

4.6.4 Procedure for Evacuation and Dehydrating System (Triple Evacuation) 4-8. . . . . . . . . . . . . . . . . . .

4.7 CHECKING AND ADDING REFRIGERANT TO SYSTEM 4-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.1 Checking Refrigerant Charge By Pressures 4-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.2 Checking Refrigerant Charge By Receiver Sight Glasses 4-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.3 Adding Full Charge 4-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7.4 Adding Partial Charge 4-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.8 CHECKING SYSTEM FOR NON--CONDENSIBLES 4-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.9 CHECKING AND REPLACING HIGH OR LOW PRESSURE SWITCH 4-11. . . . . . . . . . . . . . . . . . . . . . .

4.10 FILTER--DRIER 4-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.10.1 To Check Filter--Drier 4-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.10.2 To Replace Filter--Drier 4-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11 SERVICING THE LIQUID LINE SERVICE VALVE 4-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11.1 Coil Replacement 4-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11.2 Internal Part Replacement 4-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11.3 Replace Entire LLS Valve 4-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.12 THERMOSTATIC EXPANSION VALVE 4-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.12.1 Valve Replacement 4-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.12.2 Superheat Measurement 4-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.13 REPLACING EVAPORATOR RETURN AIR FILTERS 4-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.14 COMPRESSOR MAINTENANCE 4-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.14.1 Shaft Seal Reservoir 4-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.14.2 Refrigerant Removal From An Inoperative Compressor. 4-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.14.3 Pump Down An Operable Compressor For Repair 4-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.14.4 Removing the Compressor 4-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.14.5 Transferring Compressor Clutch 4-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.14.6 Compressor Oil Level 4-19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.14.7 Checking Unloader Operation 4-19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.15 TEMPERATURE SENSOR CHECKOUT 4-21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.16 PRESSURE TRANSDUCER CHECKOUT 4-21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.17 REPLACING SENSORS AND TRANSDUCERS 4-21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ELECTRICAL 5--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1 INTRODUCTION 5--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


LIST OF TABLES

Table 1--1 Models 1--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 1--2 Additional Support Manuals 1--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 3--1 General System Troubleshooting Procedures 3--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4-1 Temperature Sensor Resistance 4-21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4-2 Pressure Transducer Voltage 4-22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4-3 R--134a Temperature -- Pressure Chart 4-23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LIST OF FIGURES

Figure 1--1 Rooftop Unit (Eco Xcel) 1--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 1--2 Refrigerant Flow Diagram 1--6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 1--3 Heat Flow Diagram 1--7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-1 Driver Display Module-- Control Layout 2--1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-2 Driver Display Module-- Display Layout 2--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-3 Capacity Control Ladder Diagrams 2--4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-4 HVAC DISPLAY SETTINGS 2--5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-5 HVAC INFORMATION SCREENS 2--6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-6 HVAC DIAGNOSTIC SCREENS 2--7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-7 MCC Eco NG Display Alarms 2--8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-8 MCC Eco NG Coolview (Example Screenshot) 2--9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-9 MCC Eco NG Coolview (VIEW Tab) 2--10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-10 MCC Eco NG Coolview Inputs and Mode (VIEW Tab) 2--11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-11 MCC Eco NG Coolview Outputs (VIEW Tab) 2--12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-12 MCC Eco NG Coolview Error List (ERROR Tab) 2--12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-13 MCC Eco NG Coolview Statistics (HOURS Tab) 2--13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-14 MCC Eco NG Coolview Simulation Mode 2--14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-15 MCC Eco NG Coolview Data Logger 2--15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-16 MCC Eco NG Display Pinout 2--16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 2-17 MCC Eco NG ControllerPinout 2--17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-1 Opening Top Cover (Evaporator) 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-2 Removing Top Covers (Condenser) 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-3 Suction or Discharge Service Valve 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-4 Manifold Gauge Set (R--134a) 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-5 Service Connections 4-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-6 Rule of Thumb 4-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-7 Service Connections 4-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-8 Checking High Pressure Switch 4-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-9 Filter--Drier Removal 4-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-10 Liquid Line Solenoid Valve 4-13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-11 Thermostatic Expansion Valve Bulb and Thermocouple 4-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-12. Compressor Service Connections 4-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-13. Compressor Service Connections 4-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-14. Compressors 4-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


LIST OF FIGURES (Continued)

Figure 4-15. Removing Bypass Piston Plug 4-17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-16. Compressor Clutch 4-18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 4-17 Transducer Terminal Location 4-21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 5--1 Schematic 50--2104S 5--2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Figure 5--2 Schematic T50--2112S 5--3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Safety--1© 2015 Mobile Climate Control T-367 Rev. 07/2015

SAFETY SUMMARY

GENERAL SAFETY NOTICESThe following general safety notices supplement the specific warnings and cautions appearing elsewhere inthis manual. They are recommended precautions that must be understood and applied during operationandmaintenance of the equipment covered herein. A listingof the specific warnings and cautions appearingelsewhere in the manual follows the general safety notices.FIRST AIDAn injury, no matter how slight, should never go unattended. Always obtain first aid or medical attentionimmediately.OPERATING PRECAUTIONSAlways wear safety glasses.Keep hands, clothing and tools clear of the evaporator and condenser fans.No work should be performed on the unit until all start-stop switches are placed in the OFF position, andpower supply is disconnected.Always work in pairs. Never work on the equipment alone.In case of severe vibration or unusual noise, stop the unit and investigate.MAINTENANCE PRECAUTIONSBeware of unannounced starting of the evaporator and condenser fans. Do not open the unit cover beforeturning power off.Be sure power is turned off before working on motors, controllers, solenoid valves and electrical controls.Tag circuit breaker and power supply to prevent accidental energizing of circuit.Do not bypass any electrical safety devices, e.g. bridging an overload, or using any sort of jumper wires.Problems with the system should be diagnosed, and any necessary repairs performed by qualified servicepersonnel.When performing any arc welding on the unit, disconnect all wire harness connectors from the modules inthe control box. Do not remove wire harness from the modules unless you are grounded to the unit framewith a static-safe wrist strap.In case of electrical fire, open circuit switch and extinguish with CO2 (never use water).

Safety--2© 2015 Mobile Climate Control T-367 Rev. 07/2015

SPECIFIC WARNINGS AND CAUTIONS

WARNINGUse of an electro-magnetic valve as a means of positive shutoff for service is not recom

mended for safety, or good service practice.

WARNINGBe sure to observe warnings listed in the safety summary in the front of this manual be

fore performing maintenance on the hvac system

WARNINGRead the entire procedure before beginning work. Park the vehicle on a level surface,with parking brake applied. Turn main electrical disconnect switch to the off position.

WARNINGDo Not Use A Nitrogen Cylinder Without A Pressure Regulator

WARNINGDo Not Use Oxygen In Or Near A Refrigeration System As An Explosion May Occur.

WARNINGThe Filter-drier May Contain Liquid Refrigerant. Slowly Loosen The Connecting Nuts And Avoid Con

tact With Exposed Skin Or Eyes.

CAUTIONThe 50-2104 Rooftop Systems have R134a service port couplings installed on the compressor and on the unitpiping.

CAUTIONTo prevent trapping liquid refrigerant in the manifold gauge set be sure set is brought to suction pres

sure before disconnecting.

1--1© 2015 Mobile Climate Control T-367Rev. 07/2015

SECTION 1

DESCRIPTION

1.1 INTRODUCTIONThis manual contains Operating Instructions,Service Instructions and Electrical Data for theEcoXcel Model Air Conditioning and Heatingequipment furnished by Mobile Climate Control asshown in Table 1-1.

The system is identified with a Model/Serial numbertag located inside the evaporator section, on the rearbulkhead wall of the assembly. Example is shown inFigure 1-1.Models consists of a Rooftop unit containing thecondensing section, the evaporator sections and

engine compartment mounted compressor. Tocomplete the system, the air conditioning andheating equipment interfaces, electrical cabling,refrigerant piping, engine coolant piping (forheating), duct work and other componentsfurnished byMobile Climate Control and/or the busmanufacturer.

Additional support manuals are shown in Table 1-2.

Operation of the unit is controlled automatically by aMobile Climate Control Microprocessor basedcontroller. The controls maintain the vehicle'sinterior temperature at the desired set point.

Table 1-1 ModelsModel Voltage Controller With Heat Single Loop W/Covers

50-2104 24 VDCMCC EcoTemp NGMicroprocessor Yes X X

T50-2112 24 VDCMCC EcoTemp NGMicroprocessor Yes X X

Table 1-2 Additional Support ManualsMANUAL NUMBER EQUIPMENT COVERED TYPE OF MANUAL

T-367PL Eco Xcel Models Service Replacement Parts List


1.2 GENERAL DESCRIPTION1.2.1 Rooftop UnitThe rooftop unit includes the condenser section and the evaporator sections (See Figure 1-1).

Model/Serial Number PlateInterior Location

EVAPORATOR SECTIONEvaporator Section

Condenser Section

Figure 1-1 Rooftop Unit (Eco Xcel)

1.2.2 Condensing Section

The condensing section includes 2 micro-channelcondenser coils, four (4) fan and motor assembliesand receiver tank assembly with sight glasses,moisture indicator and fusible plugThe condenser coils provide heat transfer surface forcondensing refrigerant gas at a high temperature andpressure into a liquid at high temperature andpressure. The condenser fans circulate ambient airacross the outside of the condenser tubes at atemperature lower than refrigerant circulating insidethe tubes; this results in condensation of therefrigerant into a liquid. The receiver tank is also

equipped with a pressure relief valve (fusible plug)which protects the system from unsafe high pressureconditions. The filter-drier, located in the evaporatorsection, removesmoisture and debris from the liquidrefrigerant before it enters the thermostaticexpansion valve in the evaporator assembly.a. Condenser fan operation

Low Speed ON: 150 psig (10.31 bar)Low Speed OFF: 120 psig (8.27 bar)

High Speed ON: 225 psig (15.51 bar)High Speed OFF: 165 psig (11.38 bar)


1.2.3 Evaporator SectionsThe evaporator section includes the evaporator coil,two (2) blower motor assemblies, thermostaticexpansion valve, heater coil assembly, heater valve,filter/drier, service valves and condensate drainconnections.The evaporator coil provides heat transfer surfacefor transferring heat from air circulating over theoutside of the coil to refrigerant circulating inside thetubes; thus providing cooling. The heating coilsprovide a heat transfer surface for transferring heatfrom engine coolant water circulating inside thetubes to air circulating over the outside surface of thetubes, thus providing heating. The fans circulate theair over the coils. The air filters (OEM supplied)remove dirt particles from the air before it passesover the coils. The thermostatic expansion valvemeters the flow of refrigerant entering theevaporator coils. The heat valve controls the flow ofengine coolant to the heating coils upon receipt of asignal from the controller. The condensate drainconnections provide a means for connecting tubingfor disposing of condensate collected on theevaporator coils during cooling operation.1.2.4 MCC MicroprocessorThe MCC controller maintains desired temperatureset point by controlling compressor capacity, fanspeeds and heat valve operation. Refer to Section 2,for operational sequences.

1.3 REFRIGERATION SYSTEM COMPONENT SPECIFI-CATIONS

a.System Capacity: Cooling - 120,000 Btu/Hr (35 kW)Heating - 126,000 Btu/Hr (37 kW)

b. Refrigerant Charge R-134a (Approximate)

NOTERefrigerant charge will depend on hoselengths and diameters; or if there is an In-Dash unit (front evaporator). The followingshould only be used as a guideline.

50-2104 with 05G Compressor13 ± 0.5 Pounds (5.9 ± 0.23 kg)

c. CompressorCompressor 05G

No. Of Cylinders 6Weight, (Dry) With Clutch 145 Lbs. (66 kg)

Oil Charge 5.5 pints(2.6 liters)

d. Thermostatic Expansion Valve:

7 Ton Capacity- Adjustable

e. High Pressure Switch (HPS) Normally Closed

Opens at: 360±10 psig (24.82±0.68bar)Closes at: 285±15 psig (19.65±0.68bar)

f. Low Pressure Switch (LPS) Normally Open

Opens at: 6±3psig (0.41±0.20 bar)Closes at: 25±3 psig (1.7±0.20 bar)

g. Water Temperature Switch (WTS) (If Equipped)

[BusManufacturer Supplied - Suggested close on temperature rise at 105°F (41°C)]

1.4 ELECTRICAL SPECIFICATIONS - MOTORS

a. Evaporator Blower/Motor

Evaporator MotorBrushless

24 VDC

Full Load Amps (FLA) ~25

Bearing Lubrication Factory Lubricated(additional grease not required)

b. Condenser Fan Motor

Condenser MotorBrushless

24 VDC

Full Load Amps (FLA) ~7

Bearing Lubrication Factory Lubricated(additional grease not required)

c. Temperature Sensors (All)

Input Range: -40 to 167° F (-40 to 75°C)Output: NTC 10K ohms at 77° F (25°C)

d. Ambient Sensor (Controls Compressor Outputs)

Opens at: 43° F (6.1°C)Closes at: 47° F (8.3°C)


1.5 SAFETY DEVICES

System components are protected from damagecaused by unsafe operating conditions with safetydevices. Safety devices with Mobile Climate Controlsupplied equipment include high pressure switch(HPS), low pressure switch (LPS), fusible plug,circuit breakers and fuses.a. Pressure Switches

High Pressure Switch (HPS)

During the air conditioning cycle, compressor clutchoperation will automatically stop if the HPS switchcontacts open due to an unsafe operating condition.OpeningHPS contacts de-energizes the compressorclutch shutting down the compressor. The highpressure switch (HPS) is installed at the compressorassembly. See paragraph 1.3 for specifications.Low Pressure Switch (LPS)

The low pressure switch is installed on thecompressor assembly and opens on a pressure dropto shut down the system when a low pressurecondition occurs. See paragraph 1.3 forspecifications.

b. Fuses and Circuit Breakers

The Relay Board is protected against high current byan OEM supplied circuit breaker or fuse located inthe bus battery compartment (100 Amp for 24 VDCsystems is recommended). Independent fuses andcircuit breakers protect electrical circuits from highcurrent conditions. During a high current condition,the circuit protection may open.c. Ambient Lockout

Auto ModeOpens Compressor Output at: 43° F (6.1°C)Closes Compressor Output at: 47° F (8.3°C)

Defrost Mode

Opens Compressor Output at: 28° F (-2.2°C)Closes Compressor Output at: 32° F (0°C)

The ambient temperature sensor measures thecondenser inlet air temperature. These settingsprotect the compressor from damage caused byoperation at low pressures.d. Unloader Operation

The compressor is equipped with two unloaders toallow compressor operation at 33%, 66% or 100%capacity.Low Pressure Control

Energizes Unloader Output 1 (Unloads) at: 25 psig (1.7bars)De-energizes Unloader Output1 (Loads) at: 32 psig (2.2bars)

Energizes Unloader Output 2 (Unloads) at: 21 psig (1.4bars)De-energizes Unloader Output1 (Loads) at: 28 psig (1.9bars)

High Pressure Control (below 87 F (30.8C)

Energizes Unloader Output (Unloads) at: 300 psig (20.7bars)

High Pressure Control (above 92 F (33.6C)

Energizes Unloader Output (Unloads) at: 320 psig (23.4bars)

In response to the high pressure conditionsabove, the unloader remains energized for 2minutes. Once the pressures return below theparameters listed, the unloader circuit will de-energize.


1.6 AIR CONDITIONING REFRIGERATION CYCLE

When air conditioning (cooling) is selected by thecontroller, the unit operates as a vapor compressionsystem using R-134a as a refrigerant (See Figure 1-2refrigerant flow diagram). The main components ofthe system are the A/C compressor, air-cooledcondenser coils, filter-drier, thermostatic expansionvalve, liquid line solenoid valve and evaporator coils.The compressor raises the pressure and thetemperature of the refrigerant and forces it into thecondenser tubes. The condenser fan circulatessurrounding air (which is at a temperature lower thanthe refrigerant) over the outside of the condensertubes. Heat transfer is established from therefrigerant (inside the tubes) to the condenser air(flowing over the tubes). The condenser tubes havefins designed to improve the transfer of heat fromthe refrigerant gas to the air; this removal of heatcauses the refrigerant to liquefy, thus liquidrefrigerant leaves the condenser and flows to thefilter-drier.The refrigerant passes through a filter-drier where adesiccant keeps the refrigerant clean and dry.From the filter-drier, the liquid refrigerant then flowsthrough the liquid line to the sight-glass and then tothe thermostatic expansion valve. The thermalexpansion valve reduces pressure and temperature ofthe liquid andmeters the flow of liquid refrigerant tothe evaporator to obtain maximum use of theevaporator heat transfer surface.The low pressure, low temperature liquid that flowsinto the evaporator tubes is colder than the air that iscirculated over the evaporator tubes by the

evaporator fans. Heat transfer is established from theevaporator air (flowing over the tubes) to therefrigerant (flowing inside the tubes). Theevaporator tubes have aluminum fins to increaseheat transfer from the air to the refrigerant; thereforethe cooler air is circulated to the interior of the bus.The transfer of heat from the air to the lowtemperature liquid refrigerant in the evaporatorcauses the liquid to vaporize. This low temperature,low pressure vapor passes through the suction lineand returns to the compressor where the cyclerepeats.

1.7 HEATING CYCLEHeating circuit (See Figure 1-3) componentsfurnished by Mobile Climate Control include theheater cores and solenoid operated heat valve.Components furnished by the bus manufacturermay include a water temperature switch (WTS),boost water pump and floor blower convectors.The controller automatically controls the heat valvesduring the heating mode to maintain requiredtemperatures inside the bus. Engine coolant (glycolsolution) is circulated through the heating circuit bythe engine and an auxiliary boost water pump.Whenthe heat valve solenoids are de-energized, the valveswill open to allow engine coolant to flow through theheater coils. The valves are normally open.NOTE: In order to ensure water is entering theheater coils sufficiently heated, it is suggested that theOEM supplied Water Temperature Switch (WTS),(If equipped) close on temperature rise at 105°F(40.5°C).


CONDENSER SECTION

EVAPORATOR SECTION

1

2

3

4

67

5

11

8

9

10

14

12 1213

15

16

HT HP SHV

HT HP SCL

LT LP SMLT LP SHV

1. High Pressure Switch2. Low Pressure Switch3. Discharge Service Valve4. Suction Service Valve5. Discharge Check Valve6. Service Port, (High Side)7. Service Port, (Low Side)8. Pressure Transducer (SPT)

9. Thermal Expansion Valve (TXV)10. Liquid Line Sight Glass11. Pressure Transducer (DPT)12. Filter Drier Service Valve13. Filter Drier14. Liquid Line Solenoid Valve15. Receiver Tank16. Fusible Plug

Figure 1-2 Refrigerant Flow Diagram


MAIN ENGINERADIATOR

CONDENSER SECTION

EVAPORATOR SECTION

BoostPump

Heat Valve(N.O.)

INLET

OUTLET

Figure 1-3 Heat Flow Diagram

2--1© 2015 Mobile Climate Control T-367Re v. 07/2015

SECTION 2

OPERATION of MCC EcoXcel DRIVER DISPLAY

2.1 General DescriptionOperation of the MCC Eco Xcel unit is controlledthrough the MCC Driver's display.When theMCCDisplay is used to control operation,the Mode selection is selected using the “Mode”button ( item 3) on display, shown in Figure 2-1.Ability to view system pressures, sensortemperatures, component status, etc. is availableThrough the MCC Display Module.

2.2 STARTING, STOPPING AND OPERATING INSTRUC-TIONS

The MCC Drivers Display Module is marked withinternational symbols (See Figure 2-1).Before starting, electrical power must be availablefrom the bus power supply.A circuit breaker/fuse in the battery compartmentpasses power for the clutch, evaporator andcondenser assemblies.

2.2.1 Startinga. If the engine is not running, start the engine.b.When the 24VDC power is applied, the driver display will be ready to except request for system operation. Press the On/Off key (Item 1, Figure 2-1)on the display to trigger the start up sequence, controlled by the MCC Drivers display module.

2.2.2 StoppingToggling the On/Off key (Item 1, Figure 2-1) on thedisplay again will stop the system operationcontrolled by the MCC Drivers display module.

1. On/Off2. Temperature Set Point Control3. Cursor and Mode Selection4. Information/Display Settings5. Alarm Indicator

3

41

2

5

Figure 2-1 Driver Display Module- Control Layout

2--2© 2015 Mobile Climate Control T-367Rev07/2015

1. Operation Mode2. Temperature Set Point3. Fan Speed Indicator4. Interior/Exterior Temperatures5.. Alarm Indicator Symbol

5 43

2

1

Figure 2-2 Driver Display Module- Display Layout

2.3 SEQUENCE OF OPERATION2.3.1 Function of Keyswhen “Engine On” and controller

active:a. On/Off Key - Turns HVAC unit On or Off, unless OEM supplied switches are installed. It also isused to exit diagnostic menu.

b.Temperature Set Point Control Keys - Thesebuttons increase or decrease the temperature setpoint for the passenger area HVAC unit.

c. Cursor/Mode Selection Key- Used to togglethrough parameter settings in diagnostic mode orset the operatingmode to Auto, Heat, Vent, Cool,and Defrost in normal display mode.

NOTE:Depending on Customer specification, themodes of operation may be controlledstrictly through manual switches provided inthe driver's area.

d. Information/Display Settings Key - Allows access to display settings and system diagnostics.

2.3.2 Illuminating Indications (Display)

With “Engine-On” and Controller active by theOn/Off button.


2.4 BASIC OPERATING INSTRUCTIONS

When the engine is running, press the On/Offbutton on display.2.4.1 DisplayWhen the unit is ON, the display shows the interiorset point temperature, current blower speed setting,mode selection and Interior/Exterior temperatures.2.4.2 Interior Set Point Temperature ControlPress the UP (Red) or Down (Blue) keys to set thedesired interior temperature.The temperature can be adjusted between 62° F (16°C) and 82° F (28° C).2.4.3 Blower Speed SettingBlower speed operation will be set for high or lowspeed operation automatically through software, orcan be set through manual switches provided at thedriver area.

2.4.4 Mode Selection Descriptionsa. Auto - In the auto mode, the ECCnode will adjustthe individual components tomaintain the desiredset point temperature.In the auto mode, the evaporator fans will operatein an “Ultra” high speed to achieve desired setpoint faster, when the interior temperature isgreater than 5.4°F (3°C), from desired set point.In the auto mode, theA/C systemwill continue tooperate when set point is reached, and will energize the boost pump and de-energize the heatsolenoid valve to maintain temperature. This is referred to as Reheatmode, to provide additional dehumidification of interior space.

The reheatmodewill be disabled if the outside ambient air temperature is below 43° F (6.1° C).

b.Cooling - In the cooling mode, the Compressor,condenser fans and evaporator fans will be energized. The heater solenoid valve will be energized(closed), to provide full cooling.The compressor and condenser fanswill be de-energized 2 degrees F below set point. The evaporator fanswill continue to operate to circulate interiorair.

c. Heating - In the heating mode, the compressorand condenser fans will remain de-energized.Evaporator fans will be energized. The boostpumpwill be energized,and the heat solenoid valvewill be de-energized (opened), to allow enginecoolant to flow through the heater coils. If the interior temperature is more than 5° F (3° C) belowset point, the floor blowers (if equipped) will alsobe energized.

d.Defrost - In the defrost mode, the boost pumpwill be energized to provide engine coolant flow tothe drivers unit to allow defogging of the windshield.Defrost Override - In the event the main HVACsystem is “OFF”, the ability of the OEM toprovide a signal to the controller to energize theBoost Pump to provide engine coolant flow forthe Drivers Defroster is provided.

e. Vent- In the vent mode, the evaporator blowersare operated to circulate air in the bus.

2.4.5 Capacity Control “Ladder” DiagramsLadder diagrams showing system operationalcontrol logic for Auto/ Cool (Reheat system), andHeat, can be seen in Figure 2-3.


COOL

COOL

2CYLINDERS

REHEAT DUTY CYCLE

2 CYLINDERS

SETPOINT

2°F

3°F

1°F

--2°F

--4°F

--3°F

--1°F

--5°F

HEAT

0--100%

VENT

HEAT

SETPOINT

2°F

3°F

1°F

--2°F

--4°F

--3°F

--1°F

--5°F

HEAT

AUTO/COOL HEAT

WITHFLOOR BLOWERS

FLOOR BLOWERSOFF

4 CYLINDER

(Reheat)

Figure 2-3 Capacity Control Ladder Diagrams


2.4.6 Display Settings

To adjust display settings, from the main menu:

a. Press the “Information” button to enter the“View” screen (Item 4 in Figure 2-1).

b. Press and release both “Temperature ControlUP”and “Cursor UP” buttons (Items 3 in Figure 2-4)to access the display set- up screen.

c. To adjust settings, press the up or down cursorkeys to scroll to desired parameter (Item 3 inFigure 2-1).

d. To adjust settings, press the up or down temperature control keys to scroll to adjust parameter

e. After adjustment, press “Information” button(Item 4 in Figure 2-1) to exit set-up screen.

Info Button

Main Menu Screen

View Screen

Display Set-Up Screen

TemperatureControl UP Cursor UP

Figure 2-4 HVAC DISPLAY SETTINGS


2.4.7 HVAC Information ScreensThe information screens will allow user to view thesystem parameters of temperature sensors,operation hours of components and HVACequipment error logs. To enter the informationmenu:a. Press the “Information” button (Item 4 inFigure 2-1).

b. To scroll through the “Information” screens, usethe “Up and Down Cursor” buttons (Items 3 inFigure 2-1).

Examples of the available screens can be seen inFigure 2-5.

c. To reset individual error and timer hours, use temperature buttons (Item 2 in Figure 2-1). to selectparameter and press On/Off button (Item 1 inFigure 2-1) to reset the parameter.

d. To reset all error and timer hours shown on ascreen, press up or down temperature button(Item 2 in Figure 2-1) until all “=0” flashes onscreen. To reset all parameters shown, press On/Off button (Item 1 in Figure 2-1) .

e. To exit the Information screens, press the “Information” button (Item 4 in Figure 2-1).

VIEW Screen

Equipment TIMERS

Equipment ERRORS 1

Equipment ERRORS 2

CursorButtons

Info Button

TemperatureButtons

Figure 2-5 HVAC INFORMATION SCREENS


2.4.8 HVAC Diagnostics Screens

The Diagnostics screens will allow user to view thereal time status of system components. Thesescreens will aide in troubleshooting system problemswhen necessary. Outputs monitored include,pressure transducers, pressure switches, compressorunloaders, condenser fan and LLS status, heat valve,boost pump, floor blower and engine coolant switchstatus . To enter the diagnostic screens:

a. Press the “Information” button (Item 4 inFigure 2-1).

b Scroll through the screens by pressing the “Cursor” buttons (Item 3 in Figure 2-1), until diagnostic screens are shown.

c To exit the diagnostics screens, press the “Information” button (Item 4 in Figure 2-1).

Examples of the available screens can be seen inFigure 2-6.

Info Button

Cursor Buttons

Figure 2-6 HVAC DIAGNOSTIC SCREENS


2.4.9 HVAC Alarm Description

The MCC Eco TempNG Controller will notify userin the event there is a problem or interruption insystem control. The broadcasted alarms are reportedto the Eco Temp NG driver display and A/C FailLight (if applicable).

a.High or Low pressure Condition

In the event a high pressure or low pressurecondition occurs, the compressor and liquid linesolenoid will be disabled for a minimum of oneminute. High or Low pressure can be triggered byeither a pressure transducer or physical pressureswitch.

1) For high pressure condition, the condenserand evaporator fan circuits remain energized to bringthe system pressure down. After the one minutecompressor “Off” cycle, if pressures return tooperational limits, the compressor circuit willre-energize.

If the high pressure condition occurs more thanfour (4) times within a 20 minute period, thecompressor, LLS and condenser circuits will belocked out and an alarm will be broadcast to theDriver display and A/C Fail light.

2) For low pressure condition, the condenserand evaporator fan circuits remain energized. Afterthe one minute compressor “Off” cycle, if pressuresreturn to operational limits, the compressor circuitwill re-energize.If the low pressure condition occurs more than

four (4) times within a 20 minute period, thecompressor, LLS and condenser circuit will belocked out and an alarm will be broadcast to theDriver display and A/C Fail light.b. High or Low Transducer Failure

In the event a high pressure or low pressuretransducer fails, the compressor, liquid line solenoidand condenser fans will remain energized, and thecompressor will unload to two (2) cylinder operationto allow the system to provide 33% capacity untilcondition can be corrected. High and low pressureswitches will disable the cooling circuit in the eventsystem pressures reach an unsafe condition.c. Sensor Failures

In the event an out of range (Open/Short)condition occurs with the Return Air, Outside Air,Deice, or Coil sensors, the system will be unable torecognize these parameters for proper operation ofA/C system. If one of these conditions occurs, theController will trigger a code on the display to alertDriver of this condition.

When alarms occur, the ERROR screen will assist in identifying the cause of the alarm. Follow instructions inSection 2.4.7 for instructions for accessing the ERROR screens.

Alarm Indicator Symbol

Equipment ERRORS 1 Equipment ERRORS 2

Figure 2-7 MCC Eco NG Display Alarms


2.5 MCC Eco NG Coolview

MCC Coolview is designed to assist in monitoring, diagnosing and troubleshooting of the vehicle HVACsystem via a communication cable between the controller and laptop/remote computer.

CommunicationSection

Input Section Switch Input Section

Output SectionSection Tabs

Figure 2-8 MCC Eco NG Coolview (Example Screen shot)


2.5.1 Starting the MCC Coolview Applicationa. Connect USB end of USB to RS-485 converter(MCC P/N 35-0735) to USB port of computer.

b. Connect RS-485 end of USB to RS-485 converterto controller's RS-485 communication cable.

c. Connect RS-485 end of USB to RS-485 converterto controller's RS-485 communication cable.

d. Open Eco NG Coolview software on computer.e. Choose communication port associated withcommunication cable by selecting the drop downlist under “Available Port” section in Coolviewscreen (See Figure 2-9).

f. Click “Start” button (See Figure 2-9) to begincommunication between controller and Eco NGCoolview. In normal operation, the “Rx” communication light on Eco NG coolview screen andUSB to RS-485 converter will flash to indicateCommunication has been established. If transmitting a command, such as “sim on” or re-setting errors, the “Tx” will flash to indicate such.

g. Once communication has been established, software version of controller and display will beshown on Eco NG Coolview screen (SeeFigure 2-9).

Start/StopButton

SoftwareVersions

TemperatureScale Selector

CommunicationPort Selector

CommunicationIndicator Lights

Figure 2-9 MCC Eco NG Coolview (VIEW Tab)


2.5.2 Coolview Screen Layouta. Inputs and Mode Indicator- Coolview displays “real time” status of the items shown in Figure 2-10.

HVACMode/Blower Status

TemperatureSensors(Real Time)

PressureTransducers(Real Time)

Heat ValveStatus

SystemStatus

HVACSet Point

Figure 2-10 MCC Eco NG Coolview Inputs and Mode (VIEW Tab)


b.Outputs- Coolview displays “real time” status of the items shown in Figure 2-11. Indicator boxes will turngreen when outputs are switched on, and red when switched off.

ComponentOutput Component

Indicator

Figure 2-11 MCC Eco NG Coolview Outputs (VIEW Tab)

c. Error List- Coolview displays input/output, communication and compressor errors that are stored in controller's memory. Only errors that have occurred are displayed. See Figure 2-12.

Component

Error Count

Hours sincereset

ComponentError reset

Reset allErrors

Figure 2-12 MCC Eco NG Coolview Error List (ERROR Tab)


d. Statistics- Coolview displays the run hours of the following items shown in Figure 2-13.

Hours sinceresetRun hoursComponent

ComponentError reset

Reset allErrors

Figure 2-13 MCC Eco NG Coolview Statistics (HOURS Tab)


e. Simulation Mode- In simulation mode, inputs and outputs can be toggled on/off to assist withtroubleshooting and performing maintenance checks. To start simulation mode:1) Click the “Simulation Button” on the Eco Ng Coolview screen to toggle the simulation mode on or off.

2) Once simulation mode has been toggled On, click the “stand--by” button to the right of component.

3) Click the button to the right of component to engage or adjust.

SimulationMode Button

SimulationMode Indicator

Stand ByButton

Figure 2-14 MCC Eco NG Coolview Simulation Mode


f. Logger Tab- The Logger retrieves data that is saved in the Data Logger on board memory. The data can beused for diagnostics and troubleshooting.

Figure 2-15 MCC Eco NG Coolview Data Logger


2.5.3 Eco NG Display Pin out Description

Pin 1

Pin 10

Pin outPin Function Pin Function1 Power 6 J1939H2 Dimmer 7 J1939 L3 5V Output 8 J1939 Shield4 Ground 9 Ground5 RS‐485(Pos) 10 RS‐485(Neg)

Figure 2-16 MCC Eco NG Display Pin out


2.5.4 Eco NG Controller Pin out Description

1 Digital Input 2 13 Vent Mode

2 Digital Input 5 14 Condenser High Speed

3 Cool Mode 15 Condenser Low Speed

4 Defrost 16 High PSI

5 Condenser Med Speed 17 Valve 1

6 Test Mode 18 Inside Sensor

7 Low PSI 19 Digital Input 0

8 Valve 2 20 Digital Input 13

9 ADI 0 21 Off Mode

10 Digital Input 1 22 Heat Mode

11 Digital Input 4 23 Digital Input 7

12 Auto Mode 24 Digital Input 8

Connector 1 (White)25 De-ice Sensor 37 Digital Input 1126 ADI 4 38 Ground27 3928 4029 41 PWM 1 Analog30 RS-485 (Pos) 42 PWM 2 Analog31 43 ADI 1

32 PWM 1 44 ADI 2

33 PWM 2 45 ADI 5

34 Outside Sensor 46

35 ADI 3 47

36 Digital Input 9 48

Connector 1 (Gray)

1 Clutch 12

2 Digital Output 0 13

3 14 Power 2

4 Clutch (High Current) 15

5 Digital Output 2 16 Not Used

6 Power 1 17

7 18

8 19 Valve 2 CCW

9 20 Boost Pump

10

Digital Output 3

21 Valve 2 CW

11 22 Boost Pump (High Current)

Connector 2

Digital Input 10Digital Input 12

Digital Input 13

RS-485 (Neg)

GroundGround

Ground

GroundGround

49 PWM 3 (Analog Out) 61 Not Used50 PWM 3 62

Ground

51 63

52 6453 65

5V Out

54 6655 6756 6857 69

58

J1939 High 2

70

59 Valve 1 CW 71

60 Valve CCW 72

Connector 1 (Green)

PWM 4

GroundGroundGround

GroundGround

J1939 Shield 1

J1939 Low 1J1939 High 1

J1939 Shield 2J1939 Low 2

PWM 4 Analog

5V Out

5V Out

5V Out5V Out

Digital Output 1

Digital Output 4Digital Output 5



Digital Output 10

Digital Output 11

Digital Output 12

Connector 1White

Connector 1Gray

Connector 1Green

Pin 1 Pin 25 Pin 49

Pin 1

Pin 2

Connector 2

Pin 22

Pin 21

Pin 24 Pin 48 Pin 72

Figure 2-17 MCC Eco NG Controller Pin out

3--1© 2015 Mobile Climate Control T-367 Rev. 07/2015

SECTION 3

TROUBLESHOOTING

Table 3-1 General System Troubleshooting Procedures

INDICATION -TROUBLE POSSIBLE CAUSES

3.1 System Will Not CoolCompressor will not run Drive-Belt loose or defective

Clutch coil defectiveClutch malfunctionCompressor malfunction

Electrical malfunction Coach power source defectiveCircuit Breaker/safety device open

3.2 System Runs But Has Insufficient Cooling

Compressor Drive-Belt loose or defectiveCompressor valves defective

Refrigeration system Abnormal pressuresNo or restricted evaporator air flowExpansion valve malfunctionRestricted refrigerant flowLow refrigerant chargeService valves partially closedSafety device open

Restricted air flow No evaporator air flow or restrictionHeating system Heat valve stuck open3.3 Abnormal Pressures

High discharge pressure Refrigerant overchargeNoncondensable in systemCondenser motor failureCondenser coil dirty

Low discharge pressure Compressor valve(s) worn or brokenLow refrigerant charge

High suction pressure Compressor valve(s) worn or brokenLow suction pressure Suction service valve partially closed

Filter-drier inlet valve partially closedFilter-drier partially pluggedLow refrigerant chargeExpansion valve malfunctionRestricted air flow

Suction and discharge pressures tendto equalize when system is operating

Compressor valve defective

3.4 Abnormal Noise Or Vibrations

Compressor Loose mounting hardwareWorn bearingsWorn or broken valvesLiquid sluggingInsufficient oilClutch loose, rubbing or is defectiveDrive-Belt cracked, worn or looseDirt or debris on fan blades


Table 3-1 General System Troubleshooting Procedures - Continued

INDICATION -TROUBLE POSSIBLE CAUSES

3.4 Abnormal Noise Or Vibrations - Continued

Condenser or evaporator fans Loose mounting hardwareDefective bearingsBlade interferenceBlade missing or broken

3.5 No Evaporator Air Flow Or Restricted Air Flow

Air flow through coil blocked Coil frosted overDirty coilDirty filter

No or partial evaporator air flow Motor(s) defectiveMotor brushes defectiveEvaporator fan loose or defectiveFan damagedReturn air filter dirtyIcing of coilFan relay(s) defectiveSafety device openFan rotation incorrect

3.6 Expansion Valve Malfunction

Low suction pressure with high superheat

Low refrigerant chargeWax, oil or dirt plugging valve orificeIce formation at valve seatPower assembly failureLoss of bulb chargeBroken capillary tube

Low superheat and liquid slugging inthe compressor

Bulb is loose or not installed.Superheat setting too lowIce or other foreign material holding valve open

Side to side temperature difference(Warm Coil)

Wax, oil or dirt plugging valve orificeIce formation at valve seatPower assembly failureLoss of bulb chargeBroken capillary

3.7 Heating Malfunction

Insufficient heating Dirty or plugged heater coreCoolant solenoid valve(s) malfunctioning or pluggedLow coolant levelStrainer(s) pluggedHand valve(s) closedWater pumps defectiveAuxiliary Heater malfunctioning.

No Heating Coolant solenoid valve(s) malfunctioning or pluggedController malfunctionPump(s) malfunctioningSafety device open

Continuous Heating Coolant solenoid valve stuck open

4-1© 2015 Mobile Climate Control T-367 Rev. 07/2015

SECTION 4

SERVICE

WARNINGBe sure to observe warnings listed in the safety summary in the front of this manual before

performing maintenance on the hvac system.

WARNINGRead the entire procedure before beginning work. Park the coach on a level surface, with

parking brake applied. Turn main electrical disconnect switch to the off position.

NOTETo avoid damage to the earth's ozone layer, use a refrigerant recovery systemwhenever removing refrigerant. When working with refrigerants you must comply with all local government environmental laws.

4.1 MAINTENANCE SCHEDULE

SYSTEMSYSTEM

ON OFF

a. Daily Maintenance

XX

Pre-trip Inspection - after startingCheck tension and condition of V-belt

b. Weekly Inspection

X

XXX

Perform daily inspectionCheck condenser, evaporator coils and air filters for cleanlinessCheck refrigerant hoses and compressor shaft seal for leaksFeel filter-drier for excessive temperature drop across drier

c. Monthly Inspection and Maintenance

XXXXXX

Perform weekly inspection and maintenanceClean evaporator drain pans and hosesCheck wire harnesses for chafing and loose terminalsCheck fan motor bearingsCheck compressor mounting bolts for tightnessCheck fan motor brushes


4.2 OPENING TOP COVER (EVAPORATORS)To open the evaporator assembly cover do the following: (See Figure 4-1.)a. Remove all 4 of the (5/16” x 18 x 1”) retaining bolts at front end of cover.b. Grasp the front cover section under the bottom edge and lift up. Cover will pivot on the 2 hinges at rear ofcover.

Hinges

RetainingBolts

Figure 4-1 Opening Top Cover (Evaporator)

4.3 REMOVING TOP COVERS (CONDENSER)The condenser cover consist of the condenser fan deck and 2 side covers.a. To remove the side covers, remove the 14- (5/16” x 18 x 1”) from each cover and carefully lift covers off.(Item 1 & 2 in Figure 4-2)

b. To remove the fan deck, remove the 3- (5/16” x 18 x 1”) from each end of fan deck assembly, and carefullylift and unplug fan assemblies from the harness. (Item 3 in Figure 4-2)

1

2

3

Figure 4-2 Removing Top Covers (Condenser)


4.4 SUCTION AND DISCHARGE SERVICE VALVES

The suction and discharge service valves (Figure 4-3)are provided with a double seat and a gauge port,which allows servicing of the compressor andrefrigerant lines.Turning the valve stem counterclockwise (all the wayout) will backseat the valve to open the line to thecompressor and close off the gauge port. In normaloperation, the valve is backseated to allow full flowthrough the valve. The valve should always bebackseated before removing the gauge port cap.Turning the valve stem clockwise (all the wayforward) will frontseat the valve to isolate thecompressor line and open the gauge port.To measure suction or discharge pressure, midseatthe valve by opening the valve clockwise 1/4 to 1/2turn. With the valve stem midway betweenfrontseated and backseated positions, the suction or

discharge gauge port is open to both the compressorand the line.

SERVICEPORT (R-22)

VALVE STEM CAP

VALVESTEM

TO DISCHARGE ORFROM SUCTION LINE

PORT TOCOMPRESSOR

Service ValveFrontseated(clockwise)

Service ValveBackseated(counterclockwise)

ACCESS VALVE(R-134a) ACCESS VALVE CAP

Figure 4-3 Suction or Discharge Service Valve


4.4.1 Installing R-134a Manifold Guage SetA R-134a manifold gauge/hose set with self-sealinghoses is required for service of models coveredwithin this manual. To perform service using themanifold gauge/hose set, do the following:a. Preparing Manifold Gauge/Hose Set For Use1. If the manifold gauge/hose set is new or wasexposed to the atmosphere it will need to be evacuated to remove contaminants and air as follows:

2. Back seat (turn counterclockwise ) both field service couplers (see Figure 4-4) and midseat bothhand valves.

3. Connect the yellow hose to a vacuum pump andan R-134a cylinder.

4. Evacuate to 10 inches of vacuum and then chargewith R-134a to a slightly positive pressure of 1.0psig.

5. Front seat both manifold gauge set hand valvesand disconnect from cylinder. The gauge set isnow ready for use.

b. Connecting Manifold Gauge/Hose SetTo connect the manifold gauge/hose set for readingpressures, do the following:1. Remove service valve stem cap and check tomakesure it is backseated. Remove access valve cap.

2. Connect the field service coupler (see Figure 4-4)to the access valve.

3. Turn the field service coupling knob clockwise,which will open the system to the gauge set.

4. Read system pressures.5. Repeat the procedure to connect the other side ofthe gauge set.

c. Removing the Manifold Gauge Set1. While the compressor is still ON, backseat thehigh side service valve.

2. Midseat both hand valves on the manifold gaugeset and allow the pressure in the manifold gaugeset to be drawn down to low side pressure. Thisreturns any liquid thatmay be in the high side hoseto the system.

CAUTION

To prevent trapping liquid refrigerant inthe manifold gauge set be sure set isbrought to suction pressure before disconnecting.

3. Backseat the low side service valve. Backseat bothfield service couplers and frontseat bothmanifoldset hand valves. Remove the couplers from theaccess valves.

4. Install both service valve stem caps and accessvalve caps (finger-tight only).

Opened(Backseated )Hand Valve

Closed(Frontseated)Hand Valve

To Low SideAccess Valve

To High SideAccess Valve

(Red Knob)(Blue Knob)

1

43

YELLOW

2

4

56

3RED

3BLUE

2

Low PressureGauge

High PressureGauge

1. Manifold Gauge Set2. Hose Fitting (0.5-16 Acme)3. Refrigeration and/or Evacuation Hose. (SAE J2196/R-134a)4. Hose Fitting w/O-ring (M14 x 1.5)5. High Side Field Service Coupler6. Low Side Field Service Coupler

Figure 4-4 Manifold Gauge Set (R-134a)


DS1 23

4

5

7

6

8

13

9

10 1112

14

CONDENSER SECTION

EVAPORATOR SECTION

1. High Pressure Switch2. Low Pressure Switch3. Discharge Service Valve4. Suction Service Valve5. Pressure Transducer (SPT)6. Thermal Expansion Valve (TXV)7. Pressure Transducer (DPT)

8. Receiver Tank9. Filter Drier Service Valve (Inlet)10. Filter Drier Service Valve (Outlet)11. Filter Drier12. Liquid Line Solenoid Valve13. Fusible Plug14. Discharge Check Valve

Figure 4-5 Service Connections


4.4.2 SYSTEM PUMP DOWN FOR LOW SIDE REPAIR

To service or replace the thermostatic expansionvalves, filter drier, suction line or liquid line solenoidvalve. pump the refrigerant to the condenser andreceiver as follows:a. Install manifold gauge set to compressor suction&discharge valve service ports (items 4& 3). Referto Figure 4-5.

b. Frontseat the filter-drier inlet service valve (9) byturning clockwise. Disconnect suction pressuretransducer (5) electrical connector, install a jumperon the compressor mounted low pressure switch(2) (electrical connector on harness).

c. Start the system and run in cooling. Stop the unitwhen suction reaches 0 psig (0 Bar).

d.Disconnect the compressor clutch wire to disable clutch operation. Frontseat the compressordischarge service valve (3) to trap refrigerant in thehigh side of the system between the compressordischarge service valve and the filter-drier inletvalve. Wait 5minutes to verify that system remainsat approximately 0 psig (0 Bar). If system pressurerises above 0 psig (0 Bar), open the compressordischarge service valve, re-connect the compressor clutch wiring and repeat steps c and d untilthe system remains at 0 psig (0 Bar).

e. Service or replace necessary components.

f. Replace filter-drier (11). Leak check connectionson the low side of system by adding nitrogenthrough the suction service port. Refer to paragraph 4.5.

g. Energize the Liquid Line Solenoid Valve (LSV)(12) using an external power source (24 VDC) ormagnet fitted to the LSV stem.

h. Using refrigerant hoses designed for vacuum service, evacuate and dehydrate the low side of thesystem by connecting a vacuum pump to the center hose connection of manifold gauge set. Verifythe compressor suction service valve is mid-seated. Open (backseat) the manifold suction anddischarge service valves. Evacuate system to 500microns. Close off vacuum pump valve and stoppump.Wait 5minutes to verify that vacuumholds.If vacuum holds below 1000 microns, isolate themicron gauge from system to prevent exposure topressure.

i. Open compressor suction and discharge servicevalves and inlet service valve of filter drier.

j. Disconnect external 24 VDC to liquid solenoidvalve (14).

k. Re-connect compressor clutch, low pressureswitch and low pressure transducer electrical connectors.

l. Run and check refrigerant level. Refer to paragraph 4.7.


4.4.3. Removing Entire System Charge

NOTESIt is recommended that the Filter/Drier bereplaced after opening the refrigeration system for any repair.

WARNING

Use of an electro-magnetic valve as ameans of positive shutoff for service isnot recommended or good service practice.

CAUTION

For Safety, the bus and A/C systemshould be OFF, and lockout/tag outprocedures should be implemented.

To remove the entire refrigerant charge for systemcomponent repair, do the following:

a. Connect a manifold gauge set to the system asshown in Figure 4-5.

b. Connect a reclaimer to the center manifold gaugeset connection.

c. Energize the Liquid Line Solenoid Valve (LSV)(Item 12 in Figure 4-5) using an external powersource (24 VDC).

d. Recover refrigerant in accordance with reclaimermanufacturers instructions.

e. After repair is completed, a leak check should beperformed prior to system evacuation/dehydration and charging. Refer to paragraph 4.5.

4.5 REFRIGERANT LEAK CHECK

A refrigerant leak check should always be performedafter the system has been opened to replace or repaira component. To check for leaks in the refrigerationsystem, perform the following procedure:

NOTEIt is emphasized that only the correct refrigerant should be used to pressurize the system. Use of any other refrigerant will contaminate the system.

a. Ensure the service valves are open.b. Energize the Liquid Line Solenoid Valve (LSV)(Item 12 in Figure 4-5) using an external powersource (24 VDC).

c. If system is without refrigerant, charge systemwith refrigerant vapor to build up pressure toapproximately 30 PSIG (R-134a).

d. Add sufficient nitrogen to raise system pressure to150 to 200 psig (10.21 to 13.61 bar).

e. Check for leaks. The recommended procedure forfinding leaks in a system is with an electronic leakdetector. Testing joints with soap suds is satisfactory and may be necessary under conditions whenan electronic leak detector will not function correctly.

f. Remove test gas.g. Evacuate and dehydrate the system. Refer to paragraph 4.6.

h. Charge the unit. Refer to Section 4.7.

4.6 EVACUATION AND DEHYDRATION

4.6.1 GeneralThe presence of moisture in a refrigeration systemcan have many undesirable effects. The mostcommon are copper plating, acid sludge formation,“freezing-up” of metering devices by free water, andformation of acids, resulting in metal corrosion. Atriple evacuation (Refer to paragraph 4.6.4) shouldbe performed after a major system repair(compressor, evaporator, or condenserreplacement). A one time evacuation (Refer toparagraph 4.6.3) should take place after a minorsystem repair (replacement of a solenoid valve or afilter drier).4.6.2 Preparation

NOTEUsing a compound gauge for determinationof vacuum level is not recommended because of its inherent inaccuracy.

a. Evacuate and dehydrate only after pressure leaktest. Refer to paragraph 4.5.


b. Essential tools to properly evacuate and dehydrateany system include a good two stage vacuumpump with a minimum of 6 cfm (10.2 m3/hr) volume displacement.

c. Keep the ambient temperature above 60°F(15.6°C) to speed evaporation of moisture. If ambient temperature is lower than 60°F (15.6°C), icemay form before moisture removal is complete.

4.6.3 Procedure for Evacuation and Dehydrating Sys-tem (One Time Evacuation)

a. Remove refrigerant using a refrigerant recoverysystem. Refer to paragraph 4.4.3.

b. The recommendedmethod is connecting lines (refrigerant hoses designed for vacuum service) asshown in Figure 4-5.


d. Start vacuum pump. Slowly open valves halfwayand then open vacuum gauge valve.

e. Evacuate unit until vacuum gauge indicates 500microns Hg vacuum.

f. Close off pump valve and stop pump. Wait fiveminutes to see if vacuum holds below 1000 microns.

g. Close vacuum gauge valve to prevent damage tovacuum gauge. Vacuum gauges should never beexposed to positive pressure to avoid damage oraffect the vacuum gauge calibration.

h. Charge system. Refer to paragraph 4.7.3.4.6.4 Procedure for Evacuation and Dehydrating Sys-

tem (Triple Evacuation)

a. Remove refrigerant using a refrigerant recoverysystem. Refer to paragraph 4.4.3.

b. The recommendedmethod is connecting lines (refrigerant hoses designed for vacuum service) asshown in Figure 4-5 .


d. Start vacuum pump. Slowly open valves halfwayand then open vacuum gauge valve.

e. Evacuate unit until vacuum gauge indicates 2000microns Hg vacuum. Close gauge valve, vacuumpump valve, and stop vacuum pump.

f. Break the vacuum with nitrogen. Raise systempressure to approximately 2 psig.

g. Purge the nitrogen from the system.h. Repeat steps d. thru g. one time.i. Start vacuum pump and open all valves. Dehydrate unit to 500 microns Hg vacuum.

j. Close off pump valve , and stop pump. Wait fiveminutes to see if vacuum holds.

k. Close vacuum gauge valve to prevent damage tovacuum gauge. Vacuum gauges should never beexposed to positive pressure to avoid damage oraffect the vacuum gauge calibration.

l. Charge system. Refer to paragraph 4.7.3.

4.7 CHECKING AND ADDING REFRIGERANT TO SYSTEM

4.7.1 Checking Refrigerant Charge By PressuresFor the purpose of checking refrigerant pressures todetermine if the approximate charge level is correct,the following conditions and method can be used:a. Install Manifold Gauge set as described in Paragraph 4.4.1

b. Coach engine operating at high idle.c. Unit operating fully loaded in cool mode for 15minutes.

d. Compressor discharge (head) pressure to 150PSIG (R-134a). (It may be necessary to heat thecoach to provide sufficient heat load).

e. Under the above conditions, the “Rule ofThumb”method can be used as a reference for propercharge level. See Figure 4-6.

“Rule of Thumb”Air Conditioning System Pressures

For Discharge Pressure

Condenser Inlet Temperature __________ _ F

Plus (Constant) 40 _ F

Equals __________ _ F

P/T Chart Temperature __________ PSIG

For Suction Pressure

Evap. Return Air Temperature __________ _ F

Minus (Constant) 30 _ F

Equals __________ _ F

P/T Chart Temperature __________ PSIG

Figure 4-6 Rule of Thumb


4.7.2 Checking Refrigerant Charge By Receiver SightGlasses

For the purpose of checking refrigerant sight glassesto determine if the approximate charge level iscorrect, the following conditions andmethod can beused:a. Unit operating fully loaded in cool mode for 15minutes.

b. Compressor discharge (head) pressure to 150PSIG (R-134a). (It may be necessary to heat thecoach to provide sufficient heat load).

c. Under the above conditions, the system is chargedproperly when liquid refrigerant is visible in thelower sight glass located on receiver tank, with norefrigerant visible in the upper sight glass.

4.7.3 Adding Full Chargea. Install manifold gauge set at the compressor suction service valve and discharge service port. Seefigure Figure 4-5.

b. Leak check the system. Refer to paragraph 4.5.c. Evacuate and dehydrate system. Refer to paragraph 4.6.

d. Add manifold gauge set at filter drier outlet valve(item 10 in Figure 4-7). Connect center hose ofgauge set to appropriate refrigerant cylinder andhigh side hose to filter drier outlet valve serviceport. Purge air from hoses.

e. Note weight of refrigerant and cylinder.f. While system is in a deep vacuum, add liquid refrigerant to the high side of system through the filterdrier outlet valve. Monitor refrigerant weight being added using a refrigerant scale.

g. When correct charge has been added (refer toparagraph 1.3), close cylinder valve.

h. Check charge level in accordance with the procedures of paragraph 4.7.1.


DS1 23

4

5

7

6

8

13

9

10 1112

14

CONDENSER SECTION

EVAPORATOR SECTION

DS

Scale

RefrigerantBottle

1. High Pressure Switch2. Low Pressure Switch3. Discharge Service Valve4. Suction Service Valve5. Pressure Transducer (SPT)6. Thermal Expansion Valve (TXV)7. Pressure Transducer (DPT)

8. Receiver Tank9. Filter Drier Service Valve (Inlet)10. Filter Drier Service Valve (Outlet)11. Filter Drier12. Liquid Line Solenoid Valve13. Fusible Plug14. Discharge Check Valve

Figure 4-7 Service Connections


4.7.4 Adding Partial Charge

a. Check charge level in accordance with the procedures of paragraph 4.7.2.

b. Install manifold gauge set at the compressor suction service valve and discharge service port. Seefigure Figure 4-5.

c. Place appropriate refrigerant cylinder on scale.Prepare to charge vapor refrigerant by connectingcharging hose from container to center connection on gauge manifold. Purge air from hoses.

d. Run the unit in the cool mode for 15 minutes withminimum of 150 psig (R134a). It may be necessaryto heat coach to provide adequate heat load. Withthe suction service valve midseated, open the refrigerant cylinder valve and add vapor charge untilthe refrigerant level appears in the lower receiversight glass. If it is not at the proper level, add or remove refrigerant to bring it to the proper level.Refrigerant level should not appear in the upper sight glass, asthis would indicate an overcharge.

e. Backseat the suction service valve. Close the vaporvalve on the refrigerant cylinder and note weight.Remove the manifold gauge set and replace allvalve caps.

4.8 CHECKING SYSTEM FOR NON-CONDENSIBLES

To check for noncondensibles, proceed as follows:

a. Stabilize system to equalize pressure between thesuction and discharge side of the system.

b. Check temperature at the condenser and receiver.

c. Check pressure at the filter-drier inlet servicevalve.

d. Check saturation pressure as it corresponds to thecondenser/receiver temperature using the Temperature-Pressure Chart, Table 4-3.

e. If gauge reading is 3 psig (0.20 bar) or more thanthe saturation pressure in step d, noncondensiblesare present.

f. Remove refrigerant using a refrigerant recoverysystem.

g. Evacuate and dehydrate the system. Refer to paragraph 4.6.4.

h. Charge the unit. Refer to paragraph 4.7.3.

4.9 CHECKING AND REPLACING HIGH OR LOW PRES-SURE SWITCH

WARNINGDo not use a nitrogen cylinder without apressure regulator

WARNINGDo not use oxygen in or near a refrigeration system as an explosion may occur.

a. Disconnect wiring and remove switch from unit.All units are equipped with a schrader valve at thepressure switch connections.

b. Connect switch to a cylinder of dry nitrogen. SeeFigure 4-8.

1. Cylinder Valve and Gauge2. Pressure Regulator3. Nitrogen Cylinder4. Pressure Gauge (0 to 400 psig = 0 to

27.22 bar)5. Bleed--Off Valve6. 1/4 inch Connection

1

2

3

4

5

6

Figure 4-8 Checking High Pressure Switchc. Connect an ohmmeter across switch terminals.d. Set nitrogen pressure regulator higher than the upper switch setting. (refer to paragraph 1.3.)

e. For a high pressure switch, close cylinder valve andopen bleed-off valve. Open cylinder valve andslowly close bleed-off valve. The switch shouldopen, (no continuity) within required cut out tolerance. Close cylinder valve and release pressurethrough the bleed-off valve. As pressure drops,


switch should close, (continuity) within requiredcut in tolerance.

f. For a low pressure switch, close cylinder valve andbleed-off valve. Open cylinder valve to bring pressure above the cutout setting. Close the cylindervalve and slowly open bleed-off valve. The switchshould open, (no continuity) within required cutout tolerance. Open cylinder valve and increasepressure by closing the bleed-off valve. As pressure increases, switch should close, (continuity)within required cut in tolerance.

g. Replace or re-install switch (as required) and reconnect wiring.

4.10 FILTER-DRIER

4.10.1 To Check Filter-Drier

The filter-drier (see Figure 4-9) must be changed ifthe drier is partially restricted or service has beenperformed on the refrigerant system. Check for arestriction by feeling the inlet and outlet lines of thefilter-drier. If the outlet side feels cooler than theinlet side, then the filter-drier should be changed.

1543

2

3

1. Filter--Drier Inlet Service Valve2. Valve Service Port3. Hex Nut4. Filter--Drier5. Filter--Drier Outlet Service Valve

Figure 4-9 Filter-Drier Removal

4.10.2 To Replace Filter-Drier

WARNING

Use of an electro-magnetic valve as ameans of positive shutoff for service isnot recommended for safety, or good service practice.

a. Perform a system low side pump down. Refer toparagraph 4.4.2.

b. Front seat the filter drier outlet valve to isolate filter drier.

c. Lock out/Tag out the bus electrical system to prevent unit operation.

d. Using wrenches to back up the service valves,slowly loosen hex nuts retaining the filter drier.

WARNINGThe filter-drier may contain liquid refrigerant. Slowly loosen the ORS hex nuts toavoid refrigerant contact with exposedskin or eyes.

e. Place a new filter-drier near the unit for immediateinstallation.

f. Loosen or remove clamps securing the filter-drier.g. Remove the filter-drier.h. Remove seal caps from the new filter-drier. Applya light coat ofmineral oil to theO-Rings and seat inthe grooves of the filter-drier.

i. Assemble the new filter-drier to lines ensuring thatthe arrow on the body of the filter-drier points inthe direction of the refrigerant flow (refrigerantflows from the condenser to the evaporator), andthat the O-Rings have remained in place. Fingertighten ORS hex nuts.

j. Tighten the filter-drier ORS hex nuts using twoopen end wrenches.

k. Leak check filter drier connections with nitrogenby adding through filter drier service valve ports.

l. Remove nitrogen and evacuate filter drier using filter drier service ports.

m.Open filter drier service ports and restore electrical power to unit.

4.11 SERVICING THE LIQUID LINE SERVICE VALVE

The Liquid line solenoid valve (Figure 4-10) requiresno maintenance unless a malfunction to the internalparts or coil occurs. This may be caused by foreignmaterial such as: dirt, scale, or sludge in therefrigeration system, or improper voltage to the coil.There are only three possible valvemalfunctions: coilburnout, failure to open, or failure to close.Coil burnout may be caused by the following:1 Improper voltage.2 Continuous over-voltage, more than 10% or under-voltage of more than 15%.


3 Incomplete magnet circuit due to the omission ofthe coil housing or plunger.

4 Mechanical interface with movement of plungerwhich may be caused by a deformed enclosingtube.

Failure to open may be caused by the following:

1 Coil burned out or an open circuit to coil connections.

2 Improper voltage.

3 Defective plunger or deformed valve body assembly.

Failure to close may be caused by the following:

1 Defective plunger or deformed valve body assembly.

2 Foreign material in the valve.

4.11.1 Coil Replacement

a. It is not necessary to remove the refrigerant chargefrom the system.

b. Place main battery disconnect switch in OFFposition and lock.

c. Disconnect wire leads to coil.

d. Remove coil retaining screw.

e. Lift coil from enclosing tube and replace.

f. With the coil installed replace the retaining screw.

g. Connect wire leads and test operation

4.11.2 Internal Part Replacement

a. Perform a low side pump down on system. Referto paragraph 4.4.2.

b. Carefully loosen enclosing tube assembly and ensure no pressure remains within the valve. Disassemble valve and replace defective parts.

c. Assemble valve and leak check. Refer to paragraph4.5

d. Evacuate/Dehydrate low side of system. Refer toparagraph .

e.Open valves and test operation..

1. Coil retaining screw2. Coil Assembly3. Enclosing TubeAssembly

4. Gasket5. Body

1

2

3

4

5

Figure 4-10 Liquid Line Solenoid Valve

4.11.3 Replace Entire LLS Valve


b. Remove coil assembly and enclosing tube assembly. Refer to paragraph 4.11.1.

c. Un-braze valve body from piping, while using aninert gas purge to avoid system contaminationfrom carbon due to heat and oxidation.

d. Clean tubing to accept new valve body.e. Disassemble enclosing tube assembly and components from new valve. Install new valve body bybrazing body to piping while using inert gas purgeto protect system contamination.

f. Once valve body has cooled, re-install enclosingtube assembly and components on new valve.

g. Install new filter-drier.h. Leak check connections. Refer to paragraph 4.5,excluding the replacement of filter drier referenced in step ( e ).

i. Evacuate/Dehydrate low side of system. Refer toparagraph 4.6.

j. Replace coil assembly and test operation.


4.12 THERMOSTATIC EXPANSION VALVE

The thermostatic expansion valve (Figure 4-10) is anautomatic device which maintains constantsuperheat of the refrigerant gas leaving theevaporator regardless of suction pressure. The valvefunctions are: (a) automatic control of refrigerantflow to match the evaporator load and (b)prevention of liquid refrigerant entering thecompressor. Unless the valve is defective, it seldomrequires any maintenance.

4.12.1 Valve Replacement


b. Remove insulation from expansion valve andbulb.

c. Loosen retaining straps holding bulb to suctionline and detach bulb from the suction line.

d. Un-braze valve body and equalizer line from piping, while using an inert gas purge to avoid systemcontamination from carbon due to heat andoxidation.

e. Clean tubing to accept new valve body.f. Reinstall the new valve assembly into the unit in reverse order.

g. Leak check valve assembly. Refer to paragraph 4.5h. The thermal bulb is installed below the center ofthe suction line (four or eight o'clock position).This area must be clean to ensure positive bulbcontact. Strap thermal bulb to suction line. Ensurethat retaining straps are tight and renew insulation.

i. Evacuate/Dehydrate system. Refer to paragraph4.6.

j. Open isolation valvesk. Run the coach for approximately 30 minutes onfast idle.

l. Check refrigerant level. Refer to paragraph 4.7.1.

m.Check superheat. Refer to paragraph 4.12.2.4.12.2 Superheat Measurement

NOTEAll readings must be taken from the TXVbulb location and out of the direct air stream.

1. Suction Line(section view)

2. TXV Bulb Clamp3. Nut & Bolt (clamp)

4. Thermocouple5. TXV Bulb (Shownin the 4'clockposition)

1

2

3 4

5

Figure 4-11 Thermostatic Expansion Valve Bulb andThermocouple

a. Remove Presstite insulation from expansion valvebulb and suction line.

b. Loosen one TXV bulb clamp and make sure areaunder clamp is clean.

c. Place temperature thermocouple in contact withthe suction tube and parallel to the TXV bulb, andthen secure loosened clamp making sure bothbulb and thermocouple are firmly secured to suction line. See Figure 4-11. Reinstall insulationaround the bulb.

d. Connect an accurate lowpressure gauge to the lowpressure port (Figure 1-2).

e. Start bus and run on fast idle until unit has stabilized, about 20 to 30 minutes.

NOTEWhen conducting this test, the suction pressure must be at least 6 psig (0.41 bar) belowthe expansion valve maximum operatingpressure (MOP) if applicable.

f. From the temperature/pressure chart (Table 4-3),determine the saturation temperature corresponding to the evaporator outlet pressure.

g. Note the temperature of the suction gas at the expansion valve bulb. Subtract the saturation temperature from this temperature. The difference isthe superheat of the suction gas.

h. The superheat may cycle from a low to high reading. Monitor the superheat taking readings every3-5 minutes for a total of 5-6 readings. Calculatethe superheats, add the readings and divide by thenumber of readings taken to determine average superheat. Refer to paragraph 1.3 for superheat setting.


i. If superheat is not within tolerance, replace thevalve.

4.13 REPLACING EVAPORATOR RETURN AIR FILTERSThe evaporator return air filters are located in thereturn air section in ceiling. Access to the filters isaccomplished by opening the return air cover.

The filters should be checked for cleanlinessperiodically depending on operating conditions. Adirty filter will restrict air flow over the evaporatorcoil which may cause insufficient cooling or heatingand possible frost buildup on the coil. To remove thefilters, do the following.


4.14 COMPRESSOR MAINTENANCE

4.14.1 Shaft Seal ReservoirCompressor is fitted with a shaft seal reservoirequipped with a clear tube for checking level as wellas for draining oil from reservoir, it is recommendedthat the reservoir is checked and serviced regularly.

Oil Reservoir Tube

Figure 4-12. Compressor Service Connections4.14.2 Refrigerant Removal From An Inoperative Com-

pressor.To remove the refrigerant from a compressor that isnot operational, do the following:a. Attach a manifold gauge set as shown inFigure 4-13 and isolate the compressor by frontseating the suction and discharge valves.

b. Recover refrigerant with a refrigerant reclaimer. Ifthe discharge service valve port is not accessible, itwill be necessary to recover refrigerant throughthe suction service valve port only.

c. Service or replace components as required andleak check the compressor.

d. Using refrigerant hoses designed for vacuum service, connect a vacuum pump to center connection ofmanifold gauge set. Evacuate system to 500microns. Close off pump valve, isolate vacuumgauge and stop pump.Wait 5minutes to verify thatvacuum remains at or below 1000 microns.

e. Once vacuum is maintained, backseat compressorservice valves and disconnect manifold gauge set.

f. Check refrigerant level. Refer to paragraph 4.7. Itmay be necessary to clear any alarms that havebeen generated.

DS

7

1

2

3

4

5

61. Discharge ServiceValve and Port

2. Suction ServiceValve and Port

3. Manifold GaugeSet

4. Vacuum Pump5. Reclaimer6. Refrigerant Cylinder7. Thermistor VacuumGauge

Figure 4-13. Compressor Service Connections

4.14.3 Pump Down An Operable Compressor For RepairTo service an operable compressor, pump therefrigerant into the condenser coil and receiver asfollows:a. Install manifold gauge set. Refer to Figure 4-13.b. Frontseat the compressor suction service valve byturning clockwise.

c. Install a jumper on the compressor mounted lowpressure switch. Start the unit and run in coolinguntil 10 ”/hg (25.4 cm/hg) of vacuum is reached.Shut the system down and tag out system powersource.

d. Frontseat the compressor discharge service valveand wait 5 minutes to verify that vacuum is maintained. If the pressure rises above vacuum, openthe compressor discharge service valve and repeatsteps c and d until a vacuum is maintained.

e. Service or replace components as required andleak check the compressor.

f. Using refrigerant hoses designed for vacuum service, connect a vacuum pump to the center connection of the manifold gauge set. Evacuate system to 500 microns. Close off pump valve, isolatevacuum gauge and stop pump. Wait 5 minutes toverify that vacuum remains at or below 1000 microns.


g. Once vacuum is maintained, re-connect low pressure switch. Backseat compressor service valvesand disconnect manifold gauge set.

h. Check refrigerant level. Refer to paragraph 4.7. Itmay be necessary to clear any alarms that havebeen generated.

4.14.4 Removing the CompressorIf compressor is inoperative and the unit still hasrefrigerant pressure, isolate the compressor andremove the refrigerant. Refer to paragraph 4.14.2. Ifcompressor is operative, perform a pump down.Refer to paragraph 4.14.3.a. Place main battery disconnect switch in OFFposition and lock.

b. Tag anddisconnect wiring to the high pressure andlow pressure switch, unloaders and clutch.

c. Remove tension on drive belts, remove drive belts.d. Loosen bolts at suction anddischarge service valveflanges and break seal to be sure pressure is released. Remove bolts.

e. Remove four bolts holding compressor to basef. Attach sling or other device to the compressor andremove compressor from the coach through theaccess door.

NOTES

1. Service replacement compressors aresold without service valves. Valve padsare installed in their place. The optionalunloaders are not supplied, as thecylinder heads are shipped with plugs.The customer should retain the originalunloader valves for use on thereplacement compressor.

2. The piston plug that is removed from thereplacement compressor head must beinstalled in the failed compressor ifreturning for warranty or core credit.

3 Do not interchange allen-headcapscrews that mount the piston plugand unloader, they are notinterchangeable.

4 Check oil level in service replacementcompressor. (Refer to paragraphs 1.3and 4.14.6.)

g. Remove the three socket head capscrews from thecylinder head(s) that have unloader valves installed. See Figure 4-15. Remove the unloader valveand bypass piston assembly, keeping the samecapscrews with the assembly. The original unloader valve must be transferred to the replacement compressor. The plug arrangement removed from the replacement is installed in theoriginal compressor as a seal. If piston is stuck, itmay be extracted by threading a socket headcapscrew into top of piston. A small Teflon seatring at the bottom of the bypass piston plug mustbe removed.

23

4

5

78

9

1011

12

13 1

1. Electric UnloaderValve

2. Suction ServiceValve Charging Port

3. Suction ServiceValve

4. Clutch5. Oil Fill Plug6. Shaft Seal Reservoir

7. Bottom Plate8. Oil Drain Plug9. Oil Level Sight Glass10. Oil Pump11. O-ring12. Discharge Service

Valve13. Service Port

6

Figure 4-14. Compressors

GASKET

BYPASSPISTONPLUG

SPRINGFLANGECOVER

(NOT INTERCHANGEABLEWITH

CONTROL VALVE SCREWS)

COMPRESSORHEAD

CAPSCREWS

Figure 4-15. Removing Bypass Piston Plugh. Remove the pressure switches and install on replacement compressor after checking switch operation (refer to paragraph 4.9).

i. Remove clutch assemble and retain original clutchkey. Install on replacement compressor.


j. Install compressor in unit by performing the removal steps in reverse. It is recommended thatnew locknuts be used when replacing compressor.Install new gaskets on service valves and tightenbolts uniformly (55 to 80 ft-lbs suction and 20 to30 ft-lbs discharge service valves).

k. Leak check connections and replace filter-drier.l. Using refrigerant hoses designed for vacuum service, connect a vacuum pump (see Figure 4-13)and evacuate compressor to 500 microns.

m. Open compressor service valves.n. Start unit and check refrigerant level (refer to paragraph 4.7).

o. Check compressor oil level (refer to paragraph4.14.6). Add or remove oil if necessary.

p. Check compressor unloader operation.(refer toparagraph 4.14.7)

q. Backseat compressor service valves.r. Remove manifold gauge set (refer to paragraph4.4.1 ).

4.14.5 Transferring Compressor ClutchTo remove a clutch (see Figure 4-16) from acompressor and install on a replacementcompressor, do the following:

8

12

3

4

67

5

1. Compressor2. Seal Cover3. Coil4. Rotor5. Rotor Nut

6. Armature7. Spacer Nuts8. Retaining Capscrew,Lockwasher, 3/8 Washer

Figure 4-16. Compressor Clutcha. Place main battery disconnect switch in OFFposition and lock.

b. Tag and disconnect wiring to the clutch.

c. Remove tension on drive belts, remove drive belts.d. Remove the armature as a complete assembly byremoving the retaining capscrew, lockwasher, andspecial 3/8 washer from the compressor crankshaft. Use spanner wrench to prevent crankshaftrotation.

e. Install a 7/8-14 x 4” (MCC P/N 07-00381-00)capscrew into the center hole of the armature assembly and use it as a jacking bolt to remove thearmature. Use spanner wrench as in step d. to prevent crankshaft rotation.

f.Using special tool (MCC P/N 07-00242-01), remove the rotor nut and rotor. Retain original key.

g. Noting the position of the wire, remove the threebolts holding the coil to the compressor.

h. Remove every other bolt from the seal cover of thenew compressor in the same manner as the original compressor. Mount the coil assembly with thewire in the same orientation as it was mounted onthe original compressor. Tighten the mountingbolts to 45-50 ft/lbs (5.53-6.92 mkg).

i. Mount the rotor on the shaft. Seat the rotor to thehub, using the rotor nut. Be sure pulley turns freelywithout binding. Tighten rotor nut by first notingtorque necessary to start the nut on the hub andthen adding 50 ft/lbs (6.92 mkg) of torque.

4.14.5.a 3-Point Shim-less Compressor Clutch

a. Install armature on shaft using original key andtighten mounting bolt to 20 ft/lbs (2.8 mkg).

b. Perform a check of the air gap between the insideface of the armature and the mating face of the rotor. The air gap should be measured with a minimum of 50 psig (3.44 bar) in the crankcase. A preliminary check may be performed before thecrankcase is pressurized but a final check must beperformed before the clutch is operated. The gapshould be between 0.030 and 0.060 inch (7.62 to15.24 mm).

c. Loosen each of the three lock-nuts with a 7/16”box wrench while holding the jacking screws witha 1/8” hex socket wrench.

d.Back off the three jacking screws until they do nottouch the armature plate.

e. Turn the jacking screws clock-wise until theymakecontact with the armature plate and then one andone half more turns after contact.

f. Measure the initial clearance, the gap should bebetween .030” and .060”. All three set screw locations should be very close in clearance dimensions.


g. With the clearance set, hold each set screw whiletightening the lock nuts to 7 ft/lbs.

h. Reconnect wiring and test clutch operation.4.14.6 Compressor Oil LevelTo check, and if required correct, the compressor oillevel do the following:a. Operate the coach for at least one-half hour at fastidle speed, with the temperature controls at thecoolest setting, and the compressor fully loaded. Itmay benecessary to pre-heat the coach and/or operate the system in the reheat mode to keep thecompressor fully loaded throughout this procedure

b. Ensure the system is fully charged (refer to paragraph 4.7) and the compressor crankcase is warmto the touch after fifteen minutes of operation.

c. Shut off the system and immediately record the oillevel in the compressor sight glass. SeeFigure 4-14. If the compressor is not level, an average between the sight glass levels will have to bemade to determine level.

d. The correct oil level for this application should bebetween the Min/Max of the oil level sightglass.See Figure 4-14. If the oil level is correct, releasethe coach into service. If the level is above thesightglass maximum, proceed to step e. If the levelis below the sightglass minimum proceed to step f.

e. To remove oil and bring the level between theMin/Max sightglass markings, do the following:1.With the system off, connect a manifold gaugeset to the compressor suction and discharge service valves. Front seat the service valves to isolatethe compressor from the system (SeeFigure 4-13) and reclaim the refrigerant to belowatmospheric pressure. Shut off the reclaimer andverify the pressure does not rise. If the pressurerises, continue reclaiming until the pressure remains below atmospheric.

WARNINGExtreme care must be taken to ensurethat all the refrigerant has been removedfrom the compressor crankcase or the resultant pressure will forcibly dischargecompressor oil.

2.Drain or pump out compressor oil until the level is brought between the Min/Max markings.3.Evacuate the compressor to 500microns. Backseat the compressor service valves and repeat theoil level check procedure.

f. To add oil to the compressor, do the following:1.With the system off, connect a manifold gaugeset to the compressor suction and discharge service valves. Front seat both service valves to isolate the compressor from the system (SeeFigure 4-13) and reclaim the refrigerant to belowatmospheric pressure. Shut off the reclaimer andverify the pressure does not rise. If the pressurerises, continue reclaiming until the pressure remains below atmospheric.2.Add oil to compressor crankcase slowly,through the oil fill plug opening (see Figure 4-14)to bring level to mid range of allowed levels.3.Evacuate compressor to 500 microns. Backseatcompressor suction and discharge valves, startsystem and recheck oil level.4.Remove manifold gauge set.

4.14.7 Checking Unloader OperationTo check unloader operation do the following:a. Install a manifold gauge set as shown inFigure 4-13. Ensure both manifold valves arefrontseated and center connection is tight onblank fitting.

b.Midseat compressor suction service valve.c. Disconnect the suction pressure transducer. Thiswill force the controller to energize the unloader(s).

d. Start the bus and run in cooling, lower set point ifrequired to ensure system remains in full speedcooling.

e. Locate the unloader connector at the compressor.Observe manifold suction gauge while unpluggingthe connector. Pressure should decrease 3 to 5 psi(0.2 to 0.4 bar) when the unloader is unpluggedand increase the same amount as the plug is reconnected. Repeat test for second unloader if fitted.


f. If pressures do not react as described, check unloader coil or repair unloader mechanism as required.

g. When testing is complete, reconnect transducerand unloader connectors and remove manifold

gauge set.h.Disconnection of the suction pressure transducerwill cause an alarm. Once the transducer is reconnected, the alarm will go to inactive and can thenbe cleared.


4.15 TEMPERATURE SENSOR CHECKOUT

a. An accurate ohmmeter must be used to check resistance values shown in Table 4-1.

b.Due to variations and inaccuracies in ohmmeters,thermometers or other test equipment, a readingwithin two percent of the chart value would beconsidered acceptable. If a sensor is bad, the resistance value would usually be much higher or lowerthan the value given in Table 4-1.

c. At least one sensor lead must be disconnectedfrom the controller before any reading can be taken. Not doing so will result in a false reading. Twopreferred methods of determining the actual testtemperature at the sensor are an ice bath at 32°F(0°C) and/or a calibrated digital temperature meter.

Table 4-1 Temperature Sensor Resistance

TemperatureResistance In Ohms

°F °C-20 -28.9 165,300-10 -23.3 117,8000 -17.8 85,50010 -12.2 62,40020 - 6.7 46,30030 - 1.1 34,50032 0 32,70040 4.4 26,20050 10.0 19,90060 15.6 15,30070 21.1 11,90077 25 10,00080 26.7 9,30090 32.2 7,300100 37.8 5,800110 43.3 4,700120 48.9 3,800

4.16 PRESSURE TRANSDUCER CHECKOUT

NOTESystemmust be operating to check transducers.

a. With the system running use the driver display andmanifold gauges to check suction and/or discharge pressure(s) simultaneously.

b.Determine with the gauges whether one or bothpressure readouts are correct. If one is correct, exchange the pressure transducer locations. If theproblem moves with the transducer, replace thefaulty transducer.

c. If the driver display read out disagrees with bothvalues shown on the manifold gauges proceed tostep d.

d. Verify that the wiring to the transducer(s) is ingood condition.

e. Use a digital volt-ohmmeter to measure voltageacross the transducer connector corresponding toterminals A & B. See Figure 4-17. The readingshould be 5.0 VDC.

f. Use a digital volt-ohmmeter to measure voltageacross the transducer at terminals A & C. SeeFigure 4-17. Compare to values in Table 4-2. Areading within two percent of the values in thetable would be considered good.

A B

C

Figure 4-17 Transducer Terminal Location

4.17 REPLACING SENSORS AND TRANSDUCERS

a. Place main battery disconnect switch in OFFposition and lock.

b. Tag and disconnect wiring from defective sensoror transducer.

c. Remove and replace defective sensor or transducer. Sensor/transducer connections are fitted withSchreader valves to facilitate replacement.

d. Connect wiring to replacement sensor or transducer.

e. Checkout replacement sensor or transducer. Referto section 4.15 or 4.16 as applicable.

f. Repair or replace any defective component(s), asrequired.


Table 4-2 Pressure Transducer Voltage

“/hg Voltage Psig Voltage Psig Voltage Psig Voltage Psig Voltage Psig Voltage

20” 0.369 40 0.858 95 1.397 150 1.936 205 2.475 260 3.01410” 0.417 45 0.907 100 1.446 155 1.985 210 2.524 265 3.063Psig Voltage 50 0.956 105 1.495 160 2.034 215 2.573 270 3.1120 0.466 55 1.007 110 1.544 165 2.083 220 2.622 275 3.1615 0.515 60 1.054 115 1.593 170 2.132 225 2.671 280 3.21010 0.564 65 1.103 120 1.642 175 2.181 230 2.720 285 3.25915 0.614 70 1.152 125 1.691 180 2.230 235 2.769 290 3.30820 0.663 75 1.204 130 1.740 185 2.279 240 2.818 295 3.35725 0.712 80 1.250 135 1.789 190 2.328 245 2.867 300 2.40630 0.761 85 1.299 140 1.838 195 2.377 250 2.916 305 3.45535 0.810 90 1.348 145 1.887 200 2.426 255 2.965 310 3.504


Table 4-3 R-134a Temperature - Pressure Chart

Temperature Vacuum

°F °C “/hg Kg/cm@ Bar

-40 -40 14.6 37.08 0.49

.35 .37 12.3 31.25 0.42

-30 -34 9.7 24.64 0.33

-25 -32 6.7 17.00 0.23

-20 -29 3.5 8.89 0.12

-18 -28 2.1 5.33 0.07

-16 -27 0.6 1.52 0.02

Temperature Pressure

°F °C Psig Kg/cm@ Bar

-14 -26 0.4 0.03 0.03-12 -24 1.2 0.08 0.08-10 -23 2.0 0.14 0.14-8 -22 2.9 0.20 0.20-6 -21 3.7 0.26 0.26-4 -20 4.6 0.32 0.32-2 -19 5.6 0.39 0.390 -18 6.5 0.46 0.452 -17 7.6 0.53 0.524 -16 8.6 0.60 0.596 -14 9.7 0.68 0.678 -13 10.8 0.76 0.7410 -12 12.0 0.84 0.8312 -11 13.2 0.93 0.9114 -10 14.5 1.02 1.0016 -9 15.8 1.11 1.0918 -8 17.1 1.20 1.1820 -7 18.5 1.30 1.2822 -6 19.9 1.40 1.3724 -4 21.4 1.50 1.4826 -3 22.9 1.61 1.58

Temperature Pressure

°F °C Psig Kg/cm@ Bar

28 -2 24.5 1.72 1.6930 -1 26.1 1.84 1.8032 0 27.8 1.95 1.9234 1 29.6 2.08 2.0436 2 31.3 2.20 2.1638 3 33.2 2.33 2.2940 4 35.1 2.47 2.4245 7 40.1 2.82 2.7650 10 45.5 3.20 3.1455 13 51.2 3.60 3.5360 16 57.4 4.04 3.9665 18 64.1 4.51 4.4270 21 71.1 5.00 4.9075 24 78.7 5.53 5.4380 27 86.7 6.10 5.9885 29 95.3 6.70 6.5790 32 104.3 7.33 7.1995 35 114.0 8.01 7.86100 38 124.2 8.73 8.56105 41 135.0 9.49 9.31110 43 146.4 10.29 10.09115 46 158.4 11.14 10.92120 49 171.2 12.04 11.80125 52 184.6 12.98 12.73130 54 198.7 13.97 13.70135 57 213.6 15.02 14.73140 60 229.2 16.11 15.80145 63 245.6 17.27 16.93150 66 262.9 18.48 18.13155 68 281.1 19.76 19.37


SECTION 5

ELECTRICAL

5.1 INTRODUCTION

This section includes electrical wiring schematics. Theschematics shown in this section provides information for theEco Xcel model rooftop air conditioning units which are fitted

with two evaporator blower/motor assemblies in eachevaporator section, and four (4) condenser fan motorassemblies.Additional technical data regarding wiring, electricalconnectors and relay assignment are listed below .

UNIT CONTROLLER FIGURE NUMBERS

50-2104 MCC Figure 5-1T50-2112 MCC Figure 5-2


Model:50--2104

Figure

5--1

SCHEMATIC

50--2104S


Model:T50--2112

Figure

5--2

SCHEMATIC

T50--2112S

INDEX

1© 2015 Mobile Climate Control T-367Rev 07/2015

AAir Filter 4-15

CCircuit Breaker 1--4

Clutch 4-18

Compressor 1--3, 4-16, 4-17

Condenser Fan 1--3

Condensing Section 1--2

DDESCRIPTION 1--1

EELECTRICAL 5--1

Evacuation 4-7

Evacuation, One Time 4-8

Evacuation, Triple 4-8

Evaporator 1--3

Evaporator Fan 1--3

FFilter--Drier 4-12

Fuse 1--4

HHeating Cycle 1--5

High Pressure Switch 1--2, 1--3, 1--4, 4-11

LLEAK CHECK 4-7

Low Pressure Switch 1--3, 1--4, 4-11

MMaintenance Schedule 4-1

OOil Level 4-19

Operating Instructions 2--1

OPERATION 2--1

PPressure Transducer 4-21

Pump Down 4-6, 4-16

RRefrigerant Charge 1--3, 4-8, 4-9, 4-11

Refrigerant Removal 4-7, 4-16

Refrigeration Cycle 1--5

Rooftop Unit 1--2

SSAFETY Safety--1

SERVICE 4-1

Service Valves 4-3

Shaft Seal Reservoir 4-16

Starting 2--1

Stopping 2--1

Superheat 4-14

TTemperature Pressure Chart 4-23

Temperature Sensor 1--3, 4-21

Thermostatic Expansion Valve 1--3, 4-14

INDEX

2© 2015 Mobile Climate Control T-367Rev 07/2015

Top Cover 4-2

TROUBLESHOOTING 3--1

WWater Temperature Switch 1--3

3189 Farmtrail RoadYork PA 17406 USATel: 1--800--673--2431Fax: 1--717--764--0401

MCC provides exceptional performance in mobile climate comfort.

Every driver deserves the best possiblevehicle climate with MCC products

www.mcc-hvac.comMember of MCC Group S Certified ISO 9001 and ISO 1 4001.

Specifications subject to change without notice. MCC is a registered trademark.

© 2015 Mobile Climate Control T-367 Rev. 07/2015

OPERATION/SERVICE MANUAL for

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