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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 12 (HVAC SYSTEMS - AUTOMATIC)SYMPTOM TESTSTEST H: COMPRESSOR CLUTCH DOES NOT ENGAGE
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8

Test H: Compressor Clutch Does Not Engage

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Test H: Compressor Clutch Does Not Engage
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. 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. After performing system check, go to next step.
  2. With ambient air temperature above 38°F (3°C), start engine. Switch Blower Motor to high speed position. Place mode switch in defrost position. Place air temperature switch in coldest position. If A/C clutch is engaged, inspect for intermittent loose wires and/or poor connections to A/C compressor. See INTERMITTENTS  under TROUBLE SHOOTING. If A/C clutch is not engaged, go to next step.
  3. Park vehicle in shade or inside. Open windows to ventilate interior of vehicle. Allow A/C system to equalize (about 2 minutes). Turn off ignition. Connect test gauges to high and low pressure ports. Record ambient temperature at vehicle. Record readings of low and high side static pressures. Compare low and high side pressures with allowable limits for the recorded ambient temperature. Perform A/C performance test. See A/C SYSTEM PERFORMANCE  under SYSTEM TESTS. If high and low side pressures are within allowable limits for recorded ambient air temperature and if high and low pressures are within 15 psi (1.0 km/cm2 ) of each other, go to next step. If high and low side pressures are not within allowable limits for recorded ambient air temperature and/or if high and low pressures are not within 15 psi (1.0 km/cm2 ) of each other, see LEAK TESTING in GENERAL SERVICING PROCEDURES.
  4. 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 reading on scan tool to A/C high pressure reading on A/C test gauges. If high side pressure reading on scan tool and test gauges is within 15 psi (1.0 km/cm2 ) of each other, go to next step. If high side pressure reading between scan tool and test gauges are not within 15 psi (1.0 km/cm2 ) of each other, go to step  20.
  5. If HVAC Control Module is inoperative, go to step  19. If HVAC is not inoperative, go to next step
  6. Start engine. Observe COMMANDED A/C parameter in POWERTRAIN data list. Place air temperature switch in coldest position. If scan tool indicates COMMANDED A/C parameter is ON, go to step  13. If scan tool indicates COMMANDED A/C parameter is not ON, go to next step.
  7. Use scan tool to observe A/C CLUTCH (DESIRED) parameter in DASH INTEGRATION MODULE (DIM) A/C data list. If scan tool indicates that A/C (DESIRED) CLUTCH parameter is ON, go to next step. If scan tool indicates that A/C CLUTCH (DESIRED) parameter is not ON, go to step  9.
  8. Use scan tool to observe A/C CLUTCH (ACTUAL) parameter in DIM A/C data list. If scan tool indicates A/C CLUTCH (ACTUAL) parameter is ON, go to step  13. If scan tool indicates A/C CLUTCH (ACTUAL) parameter is not ON, go to step  34.
  9. Use scan tool to observe CONTROL HEAD (DESIRED) parameter in DIM A/C data list. If scan tool indicates (DESIRED) parameter is ON, go to next step. If scan tool indicates (DESIRED) parameter is not ON, go to step  12.
  10. Use scan tool to observe PRESSURE STATUS parameter in DIM A/C data list. If scan tool indicates PRESSURE STATUS parameter is normal, go to next step. If scan tool indicates, PRESSURE STATUS parameter is not normal, inspect wiring and connectors for intermittent loose wires and/or poor connections. See INTERMITTENTS  under TROUBLE SHOOTING.
  11. Use scan tool to observe TEMPERATURE STATUS parameter in DASH INTEGRATION MODULE (DIM) A/C data list. If scan tool indicates TEMPERATURE STATUS parameter is okay, go to step  31. If scan tool indicates temperature status parameter is not okay, check engine for overheating problem and repair as necessary.
  12. Use scan tool to observe A/C CONTROL HEAD (DESIRED) parameter in DIM A/C data list. Place mode switch in defrost position. If scan tool indicates A/C CONTROL HEAD (DESIRED) parameter turns ON and OFF with each command, go to step  30. If scan tool indicates A/C CONTROL HEAD (DESIRED) parameter does not turn ON and OFF with each command, go to step  33.
  13. Use scan tool to 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  17. If A/C compressor clutch relay does not turn ON and OFF with each command, go to next step.
  14. Turn ignition off. Disconnect A/C compressor clutch relay. Turn ignition on, engine off. Measure voltage between ground and terminal No. 2 (supply side) of A/C compressor clutch relay socket. If battery voltage exists, go to next step. If battery voltage does not exist, go to step  27.
  15. Connect positive lead of DVOM to coil input side of compressor clutch relay socket and negative lead to terminal C11 (Dark Green wire) of A/C compressor clutch relay socket. Using scan tool, command A/C clutch relay ON and OFF. If DVOM shows voltage each time scan tool commands A/C clutch relay ON and OFF, go to step  29. If DVOM does not show voltage each time scan tool commands A/C clutch relay ON, go to next step.
  16. If DVOM shows continuous voltage when scan tool reads ON and OFF, go to step  23. If DVOM does not show voltage when scan tool reads ON or OFF, go to step  22.
  17. Turn ignition off. Disconnect A/C compressor clutch relay from underhood fuse box (located on top of left front fender). Measure voltage between ground and terminal No. 3 of A/C compressor clutch relay. If battery voltage exists, go to next step. If battery voltage does not exist, go to step  26.
  18. Connect a 10 amp fused jumper wire between A/C CLU fuse (15-amp) and terminal C11 (Dark Green wire) of A/C compressor clutch relay socket. Turn ignition on. If A/C clutch engages, go to step  29. If A/C compressor clutch does not engage, go to step  24.
  19. Check continuity in Dark Green wire between ground and terminal "A" of A/C compressor clutch harness connector. If continuity exists, repair short to ground in Dark Green wire. Go to step  42. If continuity does not exist, go to step  21.
  20. Check low reference circuit of A/C pressure sensor for an open. Repair any damage or loose connectors found. Go to step  42. If no problem was found, go to step  28.
  21. Check ground circuit of HVAC Control Module for an open. See WIRING DIAGRAMS . If open condition is found, repair as necessary. Go to step  42. If open condition is not found, go to step  33.
  22. Check A/C compressor clutch relay control circuit of A/C compressor clutch relay for an open. See WIRING DIAGRAMS . If open condition is found, repair as necessary. Go to step  42. If open condition is not found, go to step  34.
  23. Check A/C compressor clutch relay control circuit of A/C compressor clutch relay for a short to ground. See WIRING DIAGRAMS . If short to ground is found, repair as necessary. Go to step  42. If open condition is not found, go to step  34.
  24. Check A/C compressor clutch supply voltage circuit at A/C compressor clutch for a short to ground. See WIRING DIAGRAMS . If short to ground is found, repair as necessary. Go to step  42. If open condition is not found, go to next step.
  25. Check A/C compressor clutch ground circuit for high resistance or an open. See WIRING DIAGRAMS . If high resistance or open is found, repair as necessary. Go to step  42. If open condition is not found, go to step  32.
  26. Repair A/C compressor clutch relay switch side voltage supply circuit. See WIRING DIAGRAMS . When repair is complete, go to step  42.
  27. Repair A/C compressor clutch relay coil side voltage supply circuit. See WIRING DIAGRAMS . When repair is complete, go to step  42.
  28. Check for loose wires or connectors at A/C high pressure sensor harness connector. If poor connection is found, repair as necessary. Go to step  42. If poor connection is not found, go to step  37.
  29. Check for loose wires and/or poor connections at A/C compressor clutch relay. If poor connection is found, repair as necessary. Go to step  42. If poor connection is not found, go to step  38.
  30. Check for loose wires and/or poor connections at Instrument Panel Module (IPM). If poor connection is found, repair as necessary. Go to step  42. If poor connection is not found, go to step  35.
  31. Check for loose wires and/or poor connections at Dash Integration Module (DIM). If poor connection is found, repair as necessary. Go to step  42. If poor connection is not found, go to step  36.
  32. Check for poor connections at A/C compressor clutch harness connector. If poor connection is found, repair as necessary. Go to step  42. If poor connection is not found, go to step  39.
  33. Check for loose wires and/or poor connections at HVAC control module. If poor connection is found, repair as necessary. Go to step  42. If poor connection is not found, go to step  40.
  34. Check for loose wires and/or poor connections at Powertrain Control Module (PCM). If poor connection is found, repair as necessary. Go to step  42. If poor connection is not found, go to step  41.
  35. Replace IPM. See INSTRUMENT PANEL MODULE (IPM)  under REMOVAL & INSTALLATION. When repair is complete, go to step  42.
  36. Replace DIM. See DASH INTEGRATION MODULE (DIM)  under REMOVAL & INSTALLATION. When repair is complete, go to step  42.
  37. Replace A/C refrigerant pressure switch. See A/C PRESSURE SENSOR  under REMOVAL & INSTALLATION. When repair is complete, go to step  42.
  38. Replace A/C compressor clutch relay. When repair is complete, go to step  42.
  39. Replace A/C Compressor. See COMPRESSOR  under REMOVAL & INSTALLATION. When repair is complete, go to step  42.
  40. Replace HVAC Control Module. See HVAC CONTROL MODULE  under REMOVAL & INSTALLATION. Go to step  42
  41. Replace PCM. See POWERTRAIN CONTROL MODULE in REMOVAL, OVERHAUL & INSTALLATION - AURORA & INTRIGUE article in ENGINE PERFORMANCE. Go to step  42
  42. Operate system to verify repair. If condition is corrected, system is okay. If condition is not corrected, go to step  3.
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