LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2001 >> Impala Base, 3.8 K >> Repair and Diagnosis >> External Pages >> Different car >> Section 46 (HVAC Systems - Manual) >> Symptom Tests >> Test G: Compressor Clutch Does Not Engage

Test G: Compressor Clutch Does Not Engage

WARNING: This page is about a different car, the 2002 Oldsmobile Intrigue. 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: 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-DIAGNOSTICS. Go to next step.
  2. Connect a scan tool. Start engine. Using scan tool, observe engine coolant temperature sensor (ECT) parameter in Powertrain Data list. If scan tool indicates ECT parameter is above 255°F (124°C), repair engine overheating condition. When repairs are complete, go to step  36. If scan tool does not indicate ECT parameter is above 255°F (124°C), go to next step.
  3. Ensure ambient air temperature is above 38°F (3°C). 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, check wiring for intermittent and poor 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 approximately 2 minutes. Ensure ignition switch is in OFF position. Install A/C system test gauges. Using a thermometer, record ambient temperature at vehicle. Record low side and high side STATIC pressures. Compare pressure values with specifications for ambient air temperature. See Figure. If pressure values are 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 not within 15 psi (1.05 kg/cm2 ) of each other, see A/C SYSTEM PERFORMANCE TEST  under PERFORMANCE TESTS.
  5. Turn ignition on, engine off. Using a scan tool, observe A/C HIGH SIDE PRESSURE SENSOR parameter in powertrain control module (PCM) data 2 list. Compare A/C high side pressure on scan tool to high side pressure value on A/C system test gauges. If high side pressure values are 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  22.
  6. If HVAC control assembly is inoperative, go to step  17. If HVAC control assembly is operative, go to next step.
  7. Start engine. Using a scan tool, observe A/C REQUEST SIGNAL parameter in PCM Engine Data 2 list. Place air temperature switch in coldest position. Turn blower motor to ON position. Place A/C request switch in ON position. If scan tool indicates A/C Request Signal parameter is ON, go to step  11. If scan tool does not indicate A/C Request Signal parameter is ON, go to next step.
  8. If A/C request indicator illuminates, go to step  10. If A/C request indicator does not illuminate, go to next step.
  9. Ensure blower motor is on. Turn ignition on. Locate and repair short to voltage in Dark Green wire between HVAC control module terminal "A", connector C1 and terminal B1, connector C2. If a short to voltage is found, repair as necessary. After repair, go to step  36. If circuit is okay, go to step  29.
  10. Turn ignition off. Locate and repair short to ground, high resistance, or an open in Dark Green/White wire at HVAC control module terminal A3, connector C2. If a short to ground, high resistance or an open is found, repair as necessary. After repair, go to step  36. If circuit is okay, go to step  30.
  11. Using a scan tool, command A/C Relay ON and OFF. If A/C compressor clutch relay turns ON and OFF with each command, go to step  15. If A/C compressor clutch relay does not turn ON and OFF with each command, go to next step.
  12. Turn ignition off. Disconnect A/C compressor clutch relay. Turn ignition on, engine off. Using a test light connected to ground, probe coil side battery positive voltage circuit of A/C compressor clutch relay. If test light illuminates, go to next step. If test light does not illuminate, go to step  24.
  13. Connect a test light between A/C compressor clutch relay control circuit of the A/C compressor clutch relay and the coil side battery positive voltage circuit of the A/C compressor clutch relay. Using a scan tool, command A/C 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.
  14. If test light remains illuminated with each command, go to step  20. If test light does not remain illuminated with each command, go to step  19.
  15. Turn ignition off. Disconnect A/C compressor clutch relay. Using a test light connected to ground, probe switch side battery positive voltage circuit of A/C compressor clutch relay. If test light illuminates, go to next step. If test light does not illuminate, go to step  25.
  16. Connect a 10-amp fused jumper between switch side battery positive voltage circuit of A/C compressor clutch relay and A/C compressor clutch supply voltage circuit of the A/C compressor clutch. If A/C compressor clutch engages, go to step  27. If A/C compressor clutch does not engage, go to step  21.
  17. Test ignition 3 voltage circuit of HVAC control module for a short to ground, a high resistance, or an open. If a short to ground, high resistance or an open is found, repair as necessary. After repair, go to step  36. If circuit is okay, go to next step.
  18. Test Black wire at HVAC control module terminal B8 connector C2 for an open. If an open is found, repair as necessary. After repair, go to step  36. If circuit is okay, go to step  29.
  19. Test A/C compressor clutch relay control circuit of the A/C compressor clutch relay for an open. If an open is found, repair as necessary. After repair, go to step  36. If circuit is okay, go to step  30.
  20. Test A/C compressor clutch relay control circuit of A/C compressor clutch relay for a short to ground. If a short to ground is found, repair as necessary. After repair, go to step  36. If circuit is okay, go to step  30.
  21. Test A/C compressor clutch supply voltage circuit at A/C compressor clutch for a short to ground, a high resistance, or an open. If a short to ground, high resistance or an open is found, repair as necessary. After repair, go to step  36. If circuit is okay, go to step  23.
  22. Test Red/Black wire at A/C refrigerant pressure sensor for an open. If an open is found, repair as necessary. After repair, go to step  36. If circuit is okay, go to step  26.
  23. Test Black wire between A/C compressor clutch terminal "A" and ground for a high resistance or an open. If a high resistance or an open is found, repair as necessary. After repair, go to step  36. If circuit is okay, go to step  28.
  24. Repair switch side battery positive voltage circuit of A/C compressor clutch relay. After repair, go to step  36.
  25. Repair coil side battery positive voltage circuit of A/C compressor clutch relay. After repair, go to step  36.
  26. Check A/C refrigerant pressure sensor harness connector for poor connections. If poor connection is found, repair as necessary. When repair is complete, go to step  36. If connector is okay, go to step  31.
  27. Check A/C compressor clutch relay harness connector for poor connections. If poor connection is found, repair as necessary. When repair is complete, go to step  36. If connector is okay, go to step  32.
  28. Check A/C compressor clutch harness connector for poor connections. If poor connection is found, repair as necessary. When repair is complete, go to step  35. If connector is okay, go to step  33.
  29. Check HVAC control module harness connector for poor connections. If poor connection is found, repair as necessary. When repair is complete, go to step  36. If connector is okay, go to step  34.
  30. Check PCM harness connector for poor connections. If poor connection is found, repair as necessary. When repair is complete, go to step  36. If connector is okay, go to step  35.
  31. Replace A/C pressure sensor. See A/C PRESSURE SENSOR  under REMOVAL & INSTALLATION. After repair, go to step  36.
  32. Replace A/C compressor clutch relay. See COMPRESSOR RELAY  under REMOVAL & INSTALLATION. After repair, go to step  36.
  33. Replace A/C compressor clutch. See COMPRESSOR SERVICING article in GENERAL SERVICING. After repair, go to step  36.
  34. Replace HVAC control assembly. See HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After repair, go to step  36.
  35. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. When repairs are complete, go to next step.
  36. Operate system to verify repair. If system operates normally, repair is complete. If system still malfunctions, go to step  4.
scientia non olet · About LEMON Manuals