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Test E: Compressor Clutch Does Not Disengage

WARNING: This page is about a different car, the 2002 Pontiac Grand Prix. 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 disengage when an A/C request has not been made and a Powertrain DTC has not been set.
  1. If diagnostic system check was not performed, go to DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. If diagnostic system check was performed, go to next step.
  2. Start engine. Place blower motor switch in OFF position. Place A/C request switch in OFF position. If A/C compressor operates, go to next step. If A/C compressor does not operate, check wiring systems and connectors for poor connections.
  3. Using scan tool, observe A/C REQUEST SIGNAL parameter in Powertrain Control Module engine data 2 list. If scan tool indicates A/C REQUEST SIGNAL parameter is YES, go to next step. If scan tool does not indicate A/C REQUEST SIGNAL parameter is YES, go to step  6.
  4. Check A/C request signal circuit for short to ground. If a short to ground is found, repair as necessary. When repair is complete, go to step  17. If short to ground is not found, go to next step.
  5. Turn ignition off. Remove A/C request signal circuit terminal from HVAC control assembly. Start engine. Using scan tool, observe A/C REQUEST SIGNAL parameter. If scan tool indicates A/C REQUEST SIGNAL parameter is NO, go to step  12. If scan tool indicates A/C request signal parameter is not NO, go to step  11.
  6. Remove A/C compressor clutch relay. If A/C compressor clutch turns off, go to next step. If A/C compressor clutch does not turn off, go to step  9.
  7. Using DVOM, measure resistance between switch side A/C compressor clutch relay terminals. If resistance measurement equals infinity, go to next step. If resistance measurement does not equal infinity, go to step  10.
  8. Check A/C compressor clutch relay control circuit for short to ground. See WIRING DIAGRAMS . If a short to ground is found, repair as necessary. When repair is complete, go to step  17. If short to ground is not found, go to step,  12.
  9. Check A/C compressor clutch supply voltage circuit for short to voltage. See WIRING DIAGRAMS . If a short to voltage is found, repair as necessary. When repair is complete, go to step  17. If short to voltage is not found, go to step,  14.
  10. Check A/C compressor clutch relay for poor connections. If poor connection is found, repair as necessary. When repair is complete, go to step  17. If poor connection is not found, go to step,  13.
  11. Check HVAC control assembly harness connector for poor connections. If poor connection is found, repair as necessary. When repair is complete, go to step  17. If poor connection is not found, go to step,  15.
  12. Check Powertrain Control Module (PCM) harness connector for poor connections. If poor connection is found, repair as necessary. When repair is complete, go to step  17. If poor connection is not found, go to step,  16.
  13. Replace A/C compressor clutch relay. See COMPRESSOR RELAY  under REMOVAL & INSTALLATION. When repair is complete, go to step  17.
  14. Replace A/C compressor clutch. See COMPRESSOR SERVICING article in GENERAL SERVICING. When repair is complete, go to step  17.
  15. Replace HVAC control assembly. See HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. When repair is complete, go to step  17.
  16. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CENTURY, GRAND PRIX, IMPALA, MONTE CARLO & REGAL article in ENGINE PERFORMANCE. Perform programming procedure for PCM. When repair is complete, go to next step.
  17. Operate system to verify repair. If condition is corrected, system is okay. If condition is not corrected, go to step  4.
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