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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 32 (HVAC Systems - Manual) >> Diagnostic Tests >> DTC P1546: Short Or Open In A/C Compressor Clutch Relay Circuit >> Check Procedure

Check Procedure

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.
  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. Go to next step.
  2. Ensure ambient air temperature is greater than 38°F (3°C). Turn ignition off. Inspect A/C compressor for free rotation. Start engine. Place HVAC control assembly in OFF position. If A/C compressor operates, see TEST E: COMPRESSOR CLUTCH DOES NOT DISENGAGE . If A/C compressor does not operate, go to next step.
  3. Connect scan tool. Turn ignition on, engine off. Use scan tool to command A/C relay ON and OFF in Special Functions, Engine Output Controls list. If A/C relay turns ON and OFF with each command, check connection with A/C compressor relay and relay socket. If A/C relay does not turn ON and OFF with each command, go to next step.
  4. Turn ignition off. Remove A/C clutch relay. Turn ignition on, engine off. Using a test light connected to ground, probe voltage supply terminal of A/C clutch relay. If test light illuminates, go to next step. If test light does not illuminate, go to step  11.
  5. Connect test light between ignition 3 voltage side and control circuit side of A/C compressor relay. Use scan tool to command A/C RELAY ON and OFF. If test light turns on and off with each command, go to step  9. If test light does not turn ON and OFF with each command, go to next step.
  6. If test light remains illuminated with each command of scan tool, go to step  8. If test light does not remain illuminated with each command of scan tool, go to next step.
  7. Check A/C compressor relay control circuit of A/C compressor clutch relay for a short to voltage or an open. See WIRING DIAGRAMS . If a short to voltage or an open condition exists, repair as necessary. When repair is complete, go to step  14. If short to voltage or an open condition is not found, go to step  10.
  8. Check A/C compressor relay control circuit of A/C compressor clutch relay for a short to ground. See WIRING DIAGRAMS . If a short to ground exists, repair as necessary. When repair is complete, go to step  14. If short to ground is not found, go to step  10.
  9. 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  14. If poor connection is not found, go to step  12.
  10. Check PCM harness connector for poor connections. If poor connection is found, repair as necessary. When repair is complete, go to step  14. If poor connection is not found, go to step  13.
  11. Repair A/C compressor relay ignition 3 voltage circuit. When repair is complete, go to step  14.
  12. Replace A/C compressor relay. See COMPRESSOR RELAY  under REMOVAL & INSTALLATION. When repair is complete, go to step  14.
  13. Replace and reprogram PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CENTURY, GRAND PRIX, IMPALA, MONTE CARLO & REGAL article in ENGINE PERFORMANCE. When repair is complete, go to next step.
  14. Use scan tool to clear DTCs. Recheck for DTC If DTC P1546 resets, go to step 2. If DTC does not reset, system is okay.
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