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Test L: Compressor Clutch Does Not Engage - 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. Connect scan tool to vehicle DLC. Start engine. Using scan tool, observe ELECTRONIC COOLANT TEMPERATURE parameter in powertrain data list. If scan tool indicates ELECTRONIC COOLANT TEMPERATURE 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. Compare refrigerant pressure values with specifications for 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 pressure is 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, go to next step.
  6. Start engine. Using scan tool, observe A/C REQUEST SIGNAL parameter in engine data 1 list. Place A/C request switch in ON position. If scan tool indicates YES, go to step  13. If scan tool does not indicate YES, go to step  9.
  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  37. If a circuit problem was not found, go to next step.
  8. Check HVAC control 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  37. If an open or high resistance was not found, go to step  28.
  9. Turn ignition off. Disconnect harness connector from A/C high pressure switch. Connect a 3-amp fused jumper wire between the 2 terminals of high pressure switch harness connector. Start engine. Using scan tool, observe A/C REQUEST SIGNAL parameter. Place A/C request switch in ON position. If scan tool indicates YES, go to step  29. If scan tool does not indicate YES, go to next step.
  10. Turn ignition off. Disconnect harness connector from A/C low pressure switch. Connect a 3-amp fused jumper wire between the 2 terminals of low pressure switch harness connector. Start engine. Using scan tool, observe A/C REQUEST SIGNAL parameter. Place A/C request switch in ON position. If scan tool indicates YES, go to step  26. If scan tool does not indicate YES, go to next step.
  11. Turn ignition off. Reconnect high and low pressure switches. Check A/C request signal circuit (Dark Green/White wire) for a short to ground, high resistance or an open. See WIRING DIAGRAMS . If a circuit problem was found, repair as necessary and go to step  37. If a circuit problem was not found, go to next step.
  12. Using a DVOM, measure A/C request signal circuit (Dark Green/White wire) voltage at PCM harness connector. If voltage is 12 volts, go to step  30. If voltage is not 12 volts, go to step  28.
  13. Using scan tool, command A/C 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  16.
  14. Turn ignition off. Remove compressor clutch relay from underhood fuse block. See Figure. Using a test light connected to ground, probe clutch relay terminal No. D3 (Pink wire) in underhood fuse block. See WIRING DIAGRAMS . If test light illuminates, go to next step. If test light does illuminate, go to step  24.
  15. Connect a 10-amp fused jumper wire between terminals No. D3 (Pink wire) and D1 (Dark Green wire) at underhood fuse block. See WIRING DIAGRAMS . Turn ignition on. If compressor clutch engages, go to step  25. If compressor clutch does not engage, go to step  19.
  16. Using a test light connected to ground, probe underhood fuse block terminal No. D3. See WIRING DIAGRAMS . If test light illuminates, go to next step. If test light does not illuminate, go to step  23.
  17. Connect test light between underhood fuse block terminals No. D3 and C1. SeeWIRING DIAGRAMS . Using scan tool, command compressor clutch relay on and off. If test light turns on and off with each command, go to step  25. If test light does not turn on and off with each command, go to next step.
  18. If test light remains illuminated with each command, go to step  21. If test light does not remain illuminated with each command, go to step  22.
  19. Check voltage supply circuit (Dark Green wire) to compressor clutch for an open, high resistance and a short to ground. See WIRING DIAGRAMS . If a circuit problem was found, repair as necessary and go to step  37. If a circuit problem was not found, go to next step.
  20. Check ground circuit (Black wire) to compressor clutch 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  37. If a circuit problem was not found, go to step  27.
  21. Check compressor clutch relay control circuit (Dark Green/White wire) between relay and PCM for a short to ground. See WIRING DIAGRAMS . If a short to ground was found, repair as necessary and go to step  37. If a short to ground was not found, go to step  30.
  22. Check compressor clutch relay control circuit (Dark Green/White wire) between relay and PCM for an open. See WIRING DIAGRAMS . If an open was found, repair as necessary and go to step  37. If an open was not found, go to step  30.
  23. Repair voltage supply circuit (Pink wire) to coil side of clutch relay. See WIRING DIAGRAMS . If repair is complete, go to step  37.
  24. Repair voltage supply circuit (Orange wire) to switch side of clutch relay. See WIRING DIAGRAMS . If repair is complete, go to step  37.
  25. Check harness connector at compressor clutch relay for a poor connection. If a poor connection was found, repair as necessary and go to step  37. If a poor connection was not found, go to step  31.
  26. 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  37. If a poor connection was not found, go to step  32.
  27. Check harness connector at compressor clutch for a poor connection. If a poor connection was found, repair as necessary and go to step  37. If a poor connection was not found, go to step  34
  28. Check harness connector at HVAC control assembly for a poor connection. If a poor connection was found, repair as necessary and go to step  37. If a poor connection was not found, go to step  35.
  29. 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  37. If a poor connection was not found, go to step  33.
  30. Check harness connector at PCM for a poor connection. If a poor connection was found, repair as necessary and go to step  37. If a poor connection was not found, go to step  36.
  31. Replace compressor clutch relay. After repairs are complete, go to step  37.
  32. Replace A/C low pressure switch. After repairs are complete, go to step  37.
  33. Replace A/C high pressure switch. See HIGH PRESSURE CUT-OFF SWITCH & PRESSURE RELIEF VALVE  under REMOVAL & INSTALLATION. After repairs are complete, go to step  37.
  34. Replace compressor clutch coil. See COMPRESSOR SERVICING article in GENERAL SERVICING. After repairs are complete, go to step  37.
  35. Replace main HVAC control assembly. See MAIN HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After repairs are complete, go to step  37.
  36. 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.
  37. 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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