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Test B: A/C Compressor Clutch Does Not Disengage

NOTE: For circuit reference, see CONNECTOR IDENTIFICATION  and/or WIRING DIAGRAMS  .
  1. Perform DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After check is complete, go to next step.
  2. Start engine. Place blower motor switch in OFF position. Place mode switch in OFF position. If A/C compressor clutch engages, go to next step. If A/C compressor clutch does not engage, problem is intermittent. Check wiring and connections.
  3. Using scan tool, observe A/C REQUEST SIGNAL parameter in Powertrain Engine Data 2 list. If scan tool indicates A/C REQUEST SIGNAL parameter is YES, go to next step. If scan tool indicates A/C REQUEST SIGNAL parameter is NO, go to step  6.
  4. Check A/C request signal circuit for a short to ground. Repair circuit as necessary, then go to step  17. If circuit is okay, go to next step.
  5. Turn ignition off. On 2.2L engine, disconnect PCM harness connector. On 4.3L engine, disconnect A/C high pressure switch. On all models, start engine. Using scan tool, observe A/C REQUEST SIGNAL parameter. If scan tool indicates A/C REQUEST SIGNAL parameter is YES, go to step  12. If scan tool indicates A/C REQUEST SIGNAL parameter is NO, go to step  11.
  6. Remove A/C compressor clutch relay. See COMPRESSOR RELAY  under REMOVAL & INSTALLATION. 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. Measure resistance between switch side of A/C compressor clutch relay terminals. If resistance measures infinity, go to next step. If resistance does not measure infinity, go to step  10.
  8. Check A/C compressor clutch relay control circuit for a short to ground. Repair circuit as necessary, then go to step  17. If circuit is okay, go to step  12.
  9. Check A/C compressor clutch supply voltage circuit for a short to voltage. Repair circuit as necessary, then go to step  17. If circuit is okay, go to step  14.
  10. Check A/C compressor clutch relay for loose wires and/or poor connections. Repair as necessary, then go to step  17. If wiring and connections are okay, go to step  13.
  11. Check HVAC control module harness connector for loose wires and/or poor connections. Repair as necessary, then go to step  17. If wiring and connections are okay, go to step  15.
  12. Check PCM harness connector for loose wires and/or poor connections. Repair as necessary, then go to step  17. If wiring and connections are okay, go to step  16.
  13. Replace A/C compressor clutch relay. See COMPRESSOR RELAY  under REMOVAL & INSTALLATION. After replacement, go to step  17 17.
  14. Replace A/C compressor clutch. See COMPRESSOR SERVICING article in GENERAL SERVICING. After replacement, go to step  39.
  15. Replace HVAC control assembly. See HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After replacement, go to step  17.
  16. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - BLAZER (JIMMY CANADIAN), SONOMA & S10 PICKUP article in ENGINE PERFORMANCE. After replacement, go to next step.
  17. Operate system to verify repair. If system does not operate properly, go to step  3. If system operates correctly, test is complete.
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