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United Technologies Carrier TRANSICOLD 68RM35-604-20 Operation And Service

Rearmount bus air conditioning unit
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Rearmount
68RM35-604-20
R-134a
NYCDOT
T-288

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Summary of Contents for United Technologies Carrier TRANSICOLD 68RM35-604-20

  • Page 1 Rearmount 68RM35-604-20 R-134a NYCDOT T-288...
  • Page 2 OPERATION AND SERVICE MANUAL BUS AIR CONDITIONING UNIT Rearmount 68RM35-604-20 R-134a Carrier Transicold Division, Carrier Corporation, P .O. Box 4805, Syracuse, N.Y. 13221 Carrier Corporation 1999 D Printed in U. S. A. 0699...
  • Page 3 SAFETY SUMMARY GENERAL SAFETY NOTICES The following general safety notices supplement the specific warnings and cautions appearing elsewhere in this manual. They are recommended precautions that must be understood and applied during operation and maintenance of the equipment covered herein. The general safety notices are presented in the following three sections labeled: First Aid, Operating Precautions and Maintenance Precautions.
  • Page 4 SAFETY SUMMARY SPECIFIC WARNING AND CAUTION STATEMENTS To help identify the label hazards on the Unit and explain the level of awareness each one carries, an explanation is given with the appropriate consequences: DANGER --- means an immediate hazard which WILL result in severe personal injury or death. WARNING --- means to warn against hazards or unsafe conditions which COULD result in severe personal injury or death.

  • Page 5: Table Of Contents

    TABLE OF CONTENTS Section Page SAFETY SUMMARY ............DESCRIPTION .
  • Page 6 TABLE OF CONTENTS (CONT’D) Section Page 4.11 CHECKING PRESSURE SWITCHES ....... . . 4.12 THERMOSTATIC EXPANSION VALVE .
  • Page 7 LIST OF ILLUSTRATIONS (CONT’D) Figure Page 4-8. Thermostatic Expansion Valve Bulb and Thermocouple ....4-9. Condenser Fan Motor Removal ........4-10 4-10.

  • Page 8: Description

    SECTION 1 DESCRIPTION INTRODUCTION All control systems are powered by 24 vdc This manual contains operating and electrical supplied by the bus battery and alternator or Data, and service instructions for the 68RM35 bus alternate source. air conditioning system shown in Table 1-1. The 68RM35 unit is a one-piece system consisting of a Operation of the 68RM35 units is controlled compressor, condenser, evaporator and electrical...

  • Page 9: Condenser Fan Motor Removal

    CURBSIDE ROADSIDE (CS) (RS) 1. Condenser Fan Motor (CM1) 15. Condenser Fan Switch (CFS), Lower 2. Filter-Drier Inlet Valve 16. Evaporator Fan Housing, Curbside 3. Filter-Drier 17. Discharge Line Connection 4. Low Ambient Thermostat (LATH) 18. Suction Line Connection 5. Filter-Drier Outlet Valve 19.
  • Page 10 CURBSIDE ROADSIDE (CS) (RS) 1. Electrical Control Panel (See Figure 1-3.) 2. Liquid Line Solenoid Valve 3. Thermostatic Expansion Valve (TXV) 4. Roadside Blower Housing 5. Air Filter 6. Evaporator Coil 7. Curbside Blower Housing Figure 1-2. Unit Assembly - - Inside View T-288...
  • Page 11 1. Circuit Breaker (CB5)-60 Amp 12. Circuit Breaker (CB6)-10 Amp 22. Heat Relay No. 2 (HR2) 2. Circuit Breaker (CB4)-60 Amp 13. Circuit Breaker (CB1)-15 Amp 23. Boost Pump Relay (BPR) 3. Circuit Breaker (CB3)-60 Amp 14. Cool Disable Relay (CDR) 24.

  • Page 12: Refrigeration System Component Specifications

    REFRIGERATION SYSTEM COMPONENT i. Water Temperature Switch SPECIFICATIONS Closes at 105_F (41_C) on temperature rise a. Refrigerant Charge Reheat Coolant Valve R-134a: 16 to 17 lb (7.3 to 7.7 kg) (Customer Supplied) b. Compressor k. 05G Compressor Electric Unloader Pressure Switches UPS1, UPS2 &...
  • Page 13 Table 1-2. Unloader Pressure Switch Settings UNLOADER PRESSURE SWITCH-Contacts Open/Close Settings [psig(kg/cm@)] UPS1 UPS2 UPS3 Refrigerant Load Up Unload Load Up Unload Load Up Unload (Opens) (Closes) (Opens) (Closes) (Opens) (Closes) R-134a 35 2 26 2 31 2 23 2 220 15 270 15 0.14)

  • Page 14: System Operating Controls And Components

    SYSTEM OPERATING CONTROLS AND Condenser Motor Overload (COL1 and COL2) COMPONENTS Each condenser fan motor is equipped with an a. Electronic Thermostat (TH) internal thermal protector switch. If excessively high motor temperature exists, the COL switch will The electronic thermostat senses and controls the open de-energize corresponding...
  • Page 15 rises, the switch will re-open. Refer to Table 1-2 for the ON position, EFR1 and EFR2 relays are switch settings. energized. When energized, a set of internal EFR1 and EFR2 contacts are closed to start the Unloader pressure switch UPS3 closes on evaporator fan motors.

  • Page 16: Moisture/Liquid Indicator

    Boost Pump Relay (BPR) a storage space when pumping down the system. The receiver is equipped with a sight glass, to The boost pump relay (BPR) is plugged into the observe correct charge level, relay board on the electrical control panel located moisture/liquid indicator.

  • Page 17: Air Conditioning Refrigerant Cycle

    UPS2 UPS1 UPS3 1. Compressor 2. Discharge Line 3. Discharge Line Check Valve 4. Condenser Coil 5. Receiver 6. Filter-Drier Inlet Valve 7. Filter-Drier 8. Filter-Drier Outlet Valve 9. Thermostatic Expansion Valve 10. Evaporator Coil 11. Suction Line 12. Subcooler 13.

  • Page 18: Operation

    SECTION 2 OPERATION STARTING AND STOPPING INSTRUCTIONS During Auto/Reheat mode of operation, the compressor runs continuously. Compressor a. Starting operation is only stopped when the outside 1. Start the vehicle engine. ambient temperature falls to 45 F (7.2C). The Low Ambient Thermostat (LATH) senses ambient 2.
  • Page 19 (BPR), Water Pump Relay (WPR) and Reheat RISING Coolant Valve (RCV) stopping the flow of engine TEMPERATURE coolant through the heater coil. The system is now HIGH SPEED, operating in semi-unloaded COOL mode with low 5˚F ABOVE FULLY LOADED SETPOINT speed evaporator fan operation.
  • Page 20 10 SEC Figure 2-2. Automatic High Speed Cool Mode Operation - with Reheat T-288...
  • Page 21 10 SEC Figure 2-3. Automatic High Speed Cool Mode Operation - No Reheat T-288...
  • Page 22 10 SEC F Ambient Figure 2-4. Automatic High Speed Heat Mode Operation (Below 45_ T-288...

  • Page 23: Troubleshooting

    SECTION 3 TROUBLESHOOTING Table 3-1. Troubleshooting Procedures INDICATION/ REFERENCE POSSIBLE CAUSES TROUBLE SECTION UNIT WILL NOT COOL Compressor will not run V-Belt loose or defective Check Clutch coil defective Check/Replace Clutch malfunction Check/Replace Compressor malfunction See Note. Safety device open Electrical malfunction Bus power source defective Check/Repair...

  • Page 24: Abnormal Noises Or Vibrations

    Table 3-1. Troubleshooting procedures - Continued INDICATION/ REFERENCE POSSIBLE CAUSES TROUBLE SECTION ABNORMAL NOISES OR VIBRATIONS Compressor Loose mounting hardware Check/Tighten Worn bearings See Note. Worn or broken valves See Note. Liquid slugging Insufficient oil 4.18.2 Clutch loose, rubbing or is defective Check V-belt cracked, worn or loose Check/Adjust...

  • Page 25: Service

    SECTION 4 SERVICE WARNING Beware of rotating evaporator fan when conducting following test. MAINTENANCE SCHEDULE UNIT REFERENCE REFERENCE OPERATION OPERATION SECTION a. Daily Maintenance Pre-trip inspection --- after starting 2.1 and 2.2 Check tension and condition of V-belt(s) None b. Weekly Inspection and Maintenance Perform daily inspection 4.1a Check condenser, evaporator coils and air filters...
  • Page 26 center hose as well as each other. When the low (backseated), pressure will cause vapor to flow and high side valves are frontseated (closed), the from the high side to the low side across the high and low side hoses are isolated from each compressor.

  • Page 27: System Pumpdown

    4. Backseat filter-drier inlet or outlet valve, If a recovery system is not available, proceed as depending upon which one will be used. follows: a. Equipment Required 5. With manifold set valves frontseated, connect the high side manifold hose (red) to the filter 1.

  • Page 28: Refrigerant Leak Check

    condense more liquid and raise head 7. Remove the refrigerant and nitrogen used to pressure. pressurize the system prior to leak repair. NOTE 8. Charge the unit as outlined in section 4.8. Refrigerant will flow from the system to the EVACUATION AND DEHYDRATION cylinder until the pressures equalize.
  • Page 29 6. Liquid Line Solenoid Jumper Harness - A remaining moisture in the system for the liquid line solenoid jumper harness is used to apply second evacuation. Close the cylinder valve. an external 24 vdc source to energize the 7. Repeat steps 5. and 6. solenoid.

  • Page 30: Adding Refrigerant To System

    ADDING REFRIGERANT TO SYSTEM Installing a Full Charge 1. Install a manifold gauge set as outlined in section 4.3. 2. Evacuate and dehydrate the system as outlined in section 4.7.b, as applicable, if not completed at this time. 3. Place the R-134a refrigerant cylinder on the scale and connect charging line from the cylinder to the filter-drier inlet valve.

  • Page 31: Filter-Drier Removal

    b. Unit operation in cool mode and the Open both inlet and outlet valves. compressor fully loaded (6-cylinder k. Test filter-drier for leaks. operation) for 15 minutes. Check refrigerant level. c. Head pressure at least 150 psig (for R-134a systems). (It may be necessary to block condenser air flow to raise head pressure.) Under the above conditions, the system is properly charged when the bottom receiver sight glass...

  • Page 32: Pressure Switch Continuity Check

    Table 4-1. Pressure Switch Continuity Check Ohmmeter Reading R-134a R-134a No Continuity Continuity Switches (Switch Opens ) (Switch Closes) High Press- 300 10 psig 200 10 psig ure (HPS) Low Press- 6 3 psig 25 3 psig ure (LPS) Condenser 250 10 psig 190 15 psig Fan Speed...

  • Page 33: Thermostatic Expansion Valve

    9. Attach the sensor bulb just below center of the Place insulation around TXV bulb and suction line (4 or 7 o’clock position viewing thermocouple. from cross section to the suction line, see 4. Connect suction gauge to the service port on Figure 4-8).

  • Page 34: Servicing The Reheat Coolant Valve

    CAUTION a. Defective plunger or deformed valve body assembly. If unit was recently operating, be careful of remaining hot coolant in the hoses when b. Foreign material in the valve. disassembling. It is not necessary to drain the coolant from the h.

  • Page 35: Servicing The Evaporator Fan Blower Motor Assembly

    1/16-inch Position 1/3 of blade height below shroud. 1. Blower Housing 5. Venturi 2. Fan Blower 6. Evaporator Motor 3. Unit Frame 7. Hub Set Screw 4. Venturi Clip Bolt 1. Condenser Coil 5. Fan Blade 2. Fan Blade Hub 6.

  • Page 36: Replacing The Return Air Filters

    NOTE a. Remove brush covers. If the compressor runs, pump down the b. With fingers or suitable hook, lift the brush compressor by frontseating the suction spring end up so the brush may slide up and service valve until the pressure drops to 1 out of the holder.
  • Page 37 Figure 4-11. Model 05G Compressor 4.18.2 Checking the Compressor Oil Level NOTE b. Installing It may be necessary to preheat the coach NOTE and/or operate the system in the Reheat It is important to check the compressor oil Mode to keep the compressor fully loaded level of the new compressor.

  • Page 38: Compressor Oil Charge Connections

    pressure remains at zero psig. If it does not, 2. Frontseat the suction service valve and place a continue reclaiming until the pressure remains jumper wire on the low pressure switch to by-pass the switch. at zero psig. 3. Start unit and pull crankcase pressure until 4.
  • Page 39 open suction service port to ensure there is no pressure at the oil drain plug. d. Remove the oil drain plug on the bottom plate of the compressor and drain the proper amount of oil from the compressor. Replace the plug securely back into the compressor. e.
  • Page 40 Table 4-2. R-134a Temperature - Pressure Chart BOLD NO. = Inches Mercury Vacuum (cm Hg Vac) Temperature Pressure Temperature Pressure Psig Kg/cm@ Psig Kg/cm@ ---40 ---40 14.6 49.4 37.08 0.49 ---1 26.1 180.0 1.84 1.80 ---35 ---37 12.3 41.6 31.25 0.42 27.8 191.7...

  • Page 41: Electrical Schematic Wiring Diagram

    SECTION 5 ELECTRICAL SCHEMATIC WIRING DIAGRAM NOTE If you do not find your exact unit or schematic listed on page 1-2 in the front of this book, consult your local Carrier Transicold service representative or call the technical hot line at 800-450-2211 for assistance in getting a copy of the applicable schematic.

  • Page 42: Electrical Schematic Diagram Legend And Symbols

    LEGEND SYMBOL DESCRIPTION ACHM A/C HOURMETER (OPTIONAL) SYMBOLS ACMS A/C MODE SWITCH (O.E.M. SUPPLIED) A/C RELAY ACSR1 A/C STOP RELAY #1 INDICATES RELAY BOARD CONNECTION ACSR2 A/C STOP RELAY #2 BOOST PUMP MOTOR INDICATES A WIRE GROUND BOOST PUMP RELAY 15A CIRCUIT BREAKER INDICATES CUSTORMER SUPPLIED 40A CIRCUIT BREAKER...
  • Page 43 10 SEC Figure 5-2. Electrical Schematic Diagam (Based on Drawing 68RM35-1038-12) T-288...
  • Page 44 INDEX Coolant Valve, 3-2 A/C Mode Switch, 1-7, 1-8, 2-1, 3-1 A/C Stop Light, 1-5, 1-8 Description, 1-1, 3-1 A/C Stop Relay, 1-5, 1-8 Discharge Line Check Valve, 1-2 A/C Switch, 1-5, 1-8, 4-3, 4-6 Discharge Line Isolation Valve, 1-2 ACMS Switch, 1-5 Air Conditioning Relay, 1-4 Air Conditioning Stop Relay, 1-4...
  • Page 45 INDEX Liquid line solenoid valve, 3-1 Schematic Wiring Diagrams, 5-1 Liquid--Suction Heat Exchanger, 1-2, 1-10, 1-11 Service Valves, 3-1 Low Ambient Switch, 1-5 Subcooler, 1-10, 1-11 Low Ambient Thermostat, 1-2, 1-7, 1-8, 2-1, 3-1 Suction and Discharge Service Valves, 3-1, 4-1, 4-2, 4-6, 4-8, 4-11, 4-12, 4-13 Low Pressure Gauge, 4-2 Superheat, 4-8, 4-9...

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