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Test M: Compressor Clutch Does Not Engage - Except 6.5L Diesel

WARNING: This page is about a different car, the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit reference, see CONNECTOR IDENTIFICATION  and/or WIRING DIAGRAMS  .
NOTE: Definition: A/C compressor clutch will not engage when an A/C request has been made and a Powertrain DTC has not been set.
  1. If review of system operation has been performed, go to next step. If review of system operation has not been performed, see DESCRIPTION  and OPERATION  . Review HVAC operation and perform visual inspection of system. See OPERATION . If system inspection and review of operation has been performed, go to next step.
  2. Install scan tool to vehicle DLC. Start engine. Using scan tool, observe ECT parameter in powertrain data list. If scan tool indicates ECT parameter is below 250°F (121°C), go to next step. If scan tool indicates ECT parameter is above 250°F (121°C), diagnose and repair engine overheating condition.
  3. Ensure ambient air temperature is above 38°F (3°C). Start the engine. Place blower switch in maximum speed position. Place A/C request switch in ON position. Place air temperature switch in coldest position. If compressor operates, problem is intermittent. Check system wiring, harness connectors and components for damage or defects. If compressor does not operate, go to next step.
  4. Park vehicle inside or in the shade out of direct sunlight. Open windows to ventilate vehicle interior. Turn ignition off. If A/C system was operating, allow 2 minutes for refrigerant system pressure to equalize. Install A/C manifold gauge set to system. Record ambient air temperature. Record high and low side static pressure values. Compare recorded refrigerant pressure values with specifications for the ambient air temperature. See A/C SYSTEM PERFORMANCE SPECIFICATIONS - WITH FRONT A/C  or A/C SYSTEM PERFORMANCE SPECIFICATIONS - WITH REAR A/C  tables under SYSTEM TESTS. If pressure values are within specifications for the ambient air temperature, and within 15 psi (1.05 kg/CM2 ) of each other, go to next step. If pressure values are not within specifications for the ambient air temperature, and/or not within 15 psi (1.05 kg/CM2 ) of each other, go to LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.
  5. If HVAC control assembly is inoperative, go to step  7. If HVAC control assembly is operative, got to next step.
  6. Start engine. Using scan tool, observe A/C REQUEST SIGNAL parameter in engine data 2 list. Place A/C request switch in ON position. If scan tool indicates YES, go to step  9. If scan tool does not indicate YES, go to step  10.
  7. Check voltage supply circuit (Brown wire) to HVAC control assembly for an open, high resistance or a short to ground. See WIRING DIAGRAMS . If a circuit problem was found, repair as necessary and go to step  41. If a circuit problem was not found, go to next step.
  8. Check ground circuit (Black wire) to HVAC control assembly for an open or high resistance. See WIRING DIAGRAMS . If an open or high resistance was found, repair as necessary and go to step  41. If an open or high resistance was not found, go to step  32.
  9. Using scan tool, observe A/C COMPRESSOR CYCLING SWITCH parameter. If scan tool indicates parameter is normal, go to step  16. If scan tool indicates parameter is not normal, go to step  11.
  10. Turn ignition off. Disconnect A/C high pressure switch. Connect a 3-amp fused jumper wire between the 2 terminals of A/C high pressure switch harness connector. Start engine. Place A/C request switch in the ON position. Using scan tool, observe A/C REQUEST SIGNAL parameter. If scan tool indicates that the A/C REQUEST SIGNAL parameter is YES, go to step  33. If scan tool does not indicate YES, go to step  12.
  11. Turn ignition off. Disconnect A/C low pressure switch. Connect a 3-amp fused jumper wire between the 2 terminals of A/C low pressure switch harness connector. Start engine. Using scan tool, observe A/C COMPRESSOR CYCLING SWITCH parameter. If scan tool indicates that the parameter is normal, go to step  30. If scan tool does not indicate parameter is normal, go to step  14.
  12. Turn ignition off. Reconnect A/C high pressure switch. Check A/C request signal circuit (Dark Green/White wire) for an open, high resistance or a short to ground. See WIRING DIAGRAMS . If a circuit problem was found, repair as necessary and go to step  41. If a circuit problem was not found, go to next step.
  13. Using a DVOM, measure A/C request signal voltage at PCM terminal No. C2 (Dark Green/White wire). See WIRING DIAGRAMS . If voltage is 12 volts, go to step  34. If voltage is not 12 volts, go to step  32.
  14. Check A/C low pressure switch signal circuit (Dark Green wire) for an open or high resistance. See WIRING DIAGRAMS . If an open or high resistance was found, repair as necessary and go to step  41. If an open or high resistance was not found, go to next step.
  15. Check A/C low pressure switch ground circuit (Black wire) for an open or high resistance. See WIRING DIAGRAMS . If an open or high resistance was found, repair as necessary and go to step  41. If an open or high resistance was not found, go to step  34.
  16. Using scan tool, command compressor clutch relay on and off. If clutch relay turns on and off with each command, go to next step. If clutch relay does not turn on and off with each command, go to step  19.
  17. Turn ignition off. Remove compressor clutch relay from underhood fuse block. See Figure. Using a test light connected to ground, probe underhood fuse block terminal No. C3 (Orange wire). See WIRING DIAGRAMS . If test light illuminates, go to next step. If test light does not illuminate, go to step  27.
  18. Connect a 10-amp fused jumper wire between underhood fuse block terminals No. C3 (Orange wire) and D1 (Dark Green wire). See WIRING DIAGRAMS . If compressor clutch engages, go to step  29. If compressor clutch does not engage, go to step  22.
  19. Turn ignition on. Using a test light connected to ground, probe underhood fuse block terminal No. D3 (Pink wire). See WIRING DIAGRAMS . If test light illuminates, go to next step. If test light does not illuminate, go to step  26.
  20. Connect a test light between underhood fuse block terminals No. C1 (Dark Green/White wire) and D3 (Pink wire). See WIRING DIAGRAMS . Using scan tool, command compressor clutch relay on and off. If test light turns on and off with each command, go to step  29. If test light does not turn on and off with each command, go to next step.
  21. If test light remains illuminated with each on and off command, go to step  24. If test light does not remain illuminated with each command, go to step  25.
  22. Check compressor clutch voltage supply circuit (Dark Green wire) for an open, high resistance or a short to ground. See WIRING DIAGRAMS . If a circuit problem was found, repair as necessary and go to step  41. If a circuit problem was not found, go to next step.
  23. Check compressor clutch ground circuit (Black wire) for an open or high resistance. See WIRING DIAGRAMS . If an open or high resistance was found, repair as necessary and go to step  41. If an open or high resistance was not found, go to step  31.
  24. Check compressor clutch relay control circuit (Dark Green/White wire) for a short to ground. See WIRING DIAGRAMS . If a short to ground was found, repair as necessary and go to step  41. If a short to ground was not found, go to step  34.
  25. Check compressor clutch relay control circuit (Dark Green/White wire) between relay and PCM for an open or short to voltage. See WIRING DIAGRAMS . If an open or short to voltage was found, repair as necessary and go to step  41. If an open or short to voltage was not found, go to step  34.
  26. Repair open or short to ground condition in voltage supply circuit (Pink wire) to coil side of clutch relay. See WIRING DIAGRAMS . If repair is complete, go to step  41.
  27. Repair voltage supply circuit (Orange wire) to switch side of clutch relay. See WIRING DIAGRAMS . If repair is complete, go to step  41.
  28. Repair short to ground in compressor clutch voltage supply circuit (Dark Green wire). See WIRING DIAGRAMS . If repair is complete, go to step  41.
  29. Check harness connector at compressor clutch relay for a poor connection. If a poor connection was found, repair as necessary and go to step  41. If a poor connection was not found, go to step  35.
  30. Check harness connector at A/C low pressure switch for a poor connection. If a poor connection was found, repair as necessary and go to step  41. If a poor connection was not found, go to step  36.
  31. Check harness connector at compressor clutch for a poor connection. If a poor connection was found, repair as necessary and go to step  41. If a poor connection was not found, go to step  38.
  32. Check harness connector at HVAC control assembly for a poor connection. If a poor connection was found, repair as necessary and go to step  41. If a poor connection was not found, go to step  39.
  33. Check harness connector at A/C high pressure switch for a poor connection. If a poor connection was found, repair as necessary and go to step  41. If a poor connection was not found, go to step  37.
  34. Check harness connector at PCM for a poor connection. If a poor connection was found, repair as necessary and go to step  41. If a poor connection was not found, go to step  40.
  35. Replace compressor clutch relay. See Figure. After repairs are complete, go to step  41.
  36. Replace A/C low pressure switch. After repairs are complete, go to step  41.
  37. Replace A/C high pressure switch. After repairs are complete, go to step  41.
  38. Replace compressor clutch coil. See COMPRESSOR SERVICING article in GENERAL SERVICING. After repairs are complete, go to step  41.
  39. Replace main HVAC control assembly. See MAIN HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After repairs are complete, go to step  41.
  40. Replace and program PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. If replacement is complete, go to next step.
  41. Operate system to verify repair. If the condition was corrected, system is okay. If the condition was not corrected, return to step  4.
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