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Test G: Compressor Clutch Does Not Engage

WARNING: This page is about a different car, the 2002 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For correct circuit identification and connector terminal locations, see CONNECTOR IDENTIFICATION  and/or WIRING DIAGRAMS .
NOTE: Definition: The A/C compressor clutch will not engage when an A/C request has been made and a Powertrain DTC has not been set.
  1. Perform DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. Go to next step.
  2. Start engine. Observe coolant temperature indicator. If engine coolant temperature indicator is illuminated, repair engine coolant temperature concern. If the engine coolant temperature indicator is not illuminated, go to next step.
    3. NOTE: Ambient air temperature must be greater than 38°F (3°C).
  3. Start engine. Place blower motor switch in maximum speed position. Place A/C request switch in ON position. Place air temperature switch in coldest position. If A/C compressor operates, problem is intermittent. Check wiring and connections. If A/C compressor does not operate, go to next step.
  4. Park vehicle inside or in shade. Open windows to ventilate interior of vehicle. If A/C system was operating, allow A/C system to equalize for about 2 minutes. Turn ignition off. Install manifold gauge set. Record ambient air temperature at vehicle. Record readings of low and high side STATIC pressures. Compare pressure values with specifications for ambient air temperature. See A/C PERFORMANCE TEST  under PERFORMANCE TESTS. If pressure values within specifications for 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 ambient air temperature, and/or not within 15 psi (1.05 kg/cm2 ) of each other, see LEAK TESTING in GENERAL SERVICING PROCEDURES article in GENERAL SERVICING.
  5. Turn ignition on, engine off. Using scan tool, observe A/C HIGH SIDE PRESSURE SENSOR parameter in POWERTRAIN DATA LIST. Compare A/C HIGH-SIDE PRESSURE on scan tool to high-side pressure value on manifold gauge set. If high-side pressure values within 15 psi (1.05 kg/cm2 ) of each other, go to next step. If high-side pressure values are not within 15 psi (1.05 kg/cm2 ) of each other, go to step  19.
  6. If HVAC control assembly is inoperative, go to step  10. If HVAC control assembly operative, go to next step.
  7. Start engine. Using scan tool, observe A/C REQUEST parameter in BODY CONTROL MODULE DATA LIST 2. Place blower motor switch in maximum position. Place mode switch in VENT position. Place A/C request switch in ON position. If scan tool indicates A/C Request parameter is YES, go to next step. If scan tool indicates A/C Request parameter is NO, go to step  12.
  8. Using scan tool, observe A/C RELAY COMMANDED parameter in POWERTRAIN DATA LIST 2. If scan tool indicates A/C RELAY COMMANDED parameter is ON, go to next step. If scan tool indicates A/C RELAY COMMANDED parameter is OFF, go to step  29.
  9. Using scan tool, command A/C compressor clutch relay ON and OFF. If A/C compressor clutch relay turns ON and OFF with each command, go to step  13. If A/C compressor clutch relay does not turn ON and OFF with each command, go to step  15.
  10. Test HVAC control assembly ignition "3" voltage circuit for a short to ground, a high resistance, or an open. Repair as necessary, then go to step  36. If circuit is okay, go to next step.
  11. Test HVAC control assembly ground circuit for an open. Repair as necessary, then go to step  36. If circuit is okay, go to step  27.
  12. Start engine. Place A/C request switch in ON position. Measure voltage between A/C request circuit at BCM and ground. If voltage measures near 12 volts, go to step  28. If voltage does not measure near 12 volts, go to step  17.
  13. Turn ignition off. Disconnect A/C compressor clutch relay. Probe A/C compressor clutch relay switch side voltage supply circuit with a test light connected to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step  22.
  14. Connect a 10-amp fused jumper wire between A/C compressor clutch relay switch side voltage circuit and A/C compressor clutch supply voltage circuit. Turn ignition on, engine off. If A/C compressor clutch engages, go to step  25. If A/C compressor clutch does not engage, go to step  18.
  15. Turn ignition off. Disconnect A/C compressor clutch relay. Turn ignition on, engine off. Probe A/C compressor clutch relay coil side voltage supply circuit with a test light connected to ground. If test light illuminates, go to next step. If test light does not illuminate, go to step  21.
  16. Connect a test light between A/C compressor clutch relay control circuit and coil side voltage supply circuit. Using scan tool, command A/C 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 step  23.
  17. Test A/C request signal circuit for a short to ground, a high resistance, or an open. Repair as necessary, then go to step  36. If circuit is okay, go to step  27.
  18. Test A/C compressor clutch supply voltage circuit at A/C compressor clutch for a short to ground, a high resistance, or an open. Repair as necessary, then go to step  36. If circuit is okay, go to step  20.
  19. Test A/C pressure sensor ground circuit for an open. Repair as necessary, then go to step  36. If circuit is okay, go to step  24.
  20. Test A/C compressor clutch ground circuit for a high resistance or an open. Repair as necessary, then go to step  36. If circuit is okay, go to step  26.
  21. Repair A/C compressor clutch relay coil side voltage supply circuit. After repairs are complete, go to step  36.
  22. Repair A/C compressor clutch relay switch side voltage supply circuit. After repairs are complete, go to step  36.
  23. Test A/C compressor clutch relay control circuit for an open, or a short to ground. Repair as necessary, then go to step  36. If circuit is okay, go to step  29.
  24. Inspect for poor connections at A/C high pressure sensor harness connector. Repair as necessary, then go to step  36. If connections are okay, go to step  30.
  25. Inspect for poor connections at A/C compressor clutch relay. Repair as necessary, then go to step  36. If connections are okay, go to step  31.
  26. Inspect for poor connections at A/C compressor clutch coil harness connector. Repair as necessary, then go to step  36. If connections are okay, go to step  32.
  27. Inspect for poor connections at HVAC control assembly harness connector. Repair as necessary, then go to step  36. If connections are okay, go to step  33.
  28. Inspect for poor connections at BCM. Repair as necessary, then go to step  36. If connections are okay, go to step  34.
  29. Inspect for poor connections at PCM harness connector. Repair as necessary, then go to step  36. If connections are okay, go to step  35.
  30. Replace A/C high pressure switch. See COMPRESSOR SERVICING in GENERAL SERVICING article in GENERAL SERVICING. After replacement, go to step  36.
  31. Replace A/C compressor clutch relay. See COMPRESSOR CLUTCH RELAY  under REMOVAL & INSTALLATION. After replacement, go to step  36.
  32. Replace A/C compressor clutch coil. See COMPRESSOR SERVICING in GENERAL SERVICING article in GENERAL SERVICING. After replacement, go to step  36.
  33. Replace HVAC control assembly. See HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After replacement, go to step  36.
  34. Replace BCM. See appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. After replacement, go to step  36.
  35. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. After replacement, go to next step.
  36. Operate system to verify repair. If system operates properly, system is okay. If system does not operate properly, go to step  4.
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