HVAC System Compressor Clutch Controls: Diagnosis GMC Envoy I

A/C CLUTCH CIRCUIT DIAGNOSIS

To help save diagnostic time, ALWAYS check for blown fuses or fusible links before proceeding with any testing. If fuses are blown, locate and repair short circuit before replacing fuses.

Ensure all related relay and wire harness connections are clean and tight. Repair as necessary. See WIRING DIAGRAMS .

Diagnosis

1. If On-Board Diagnostic (OBD) System Check has not been performed, see OBD SYSTEM CHECK in TESTS W/CODES article in ENGINE PERFORMANCE. If OBD SYSTEM CHECK has been performed, go to next step.
2. Install scan tool. Check if DTC P0530 is set. If DTC P0530 is set, see TESTS W/CODES article in ENGINE PERFORMANCE. If DTC P0530 is not set, go to next step.
3. Turn ignition on, engine off. Check if compressor clutch is engaged. If compressor clutch is engaged, go to next step. If compressor clutch is not engaged, go to step 5).
4. Disconnect A/C clutch relay. If compressor clutch disengages, go to step 6). If compressor clutch does not disengage, go to step 7).
5. Start engine and allow it to reach normal operating temperature. Cycle A/C selector switch on and off. If compressor clutch cycles on and off, go to step 8). If compressor clutch does not cycle on and off, go to step 9).
6. Using a test light connected to battery voltage, probe A/C clutch relay control circuit terminal (Dark Green/White wire) at A/C clutch relay connector. If test light illuminates, go to step 10). If test light does not illuminate, go to step 11).
7. Disconnect compressor clutch harness connector. If compressor clutch disengages, go to step 12). If compressor clutch does not disengage, go to step 13).
8. Turn ignition on, engine off. Install A/C manifold gauge set. Observe A/C high-side pressure readings on gauge set and compare to scan tool reading. If high-side pressure readings are within 20 psi (1.4 kg/cm 2 ) of each other, go to step 36). If pressures are not as specified, go to step 14).
9. Turn A/C on, then off. If scan tool indicates A/C was requested, then not requested, go to step 15). If operation is not as specified, go to step 16).
10. Check A/C clutch relay control circuit (Dark Green/White wire) for a short to ground. Repair as necessary. Go to step 36). If no problem is found, go to step 22).
11. Replace A/C clutch relay. Go to step 36).
12. Repair short to power in compressor clutch battery feed circuit (Dark Green wire). Go to step 36).
13. Replace faulty compressor clutch coil assembly. Go to step 36).
14. Turn ignition on, engine off. Disconnect A/C pressure sensor harness connector. Using a DVOM, measure voltage between battery voltage and Black wire at A/C pressure sensor harness connector. If reading is battery voltage, go to step 18). If reading is not as specified, go to step 19).
15. With ignition on, engine off, observe A/C HIGH-SIDE pressure reading on scan tool. If reading is 40-430 psi (2.8-30.2 kg/cm 2 ), go to step 20). If reading is not as specified, go to step 21).
16. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Using a test light connected to ground, probe A/C selector switch input circuit (Light Blue wire) at PCM harness connector. Cycle A/C selector switch on and off. If test light toggles on and off, go to next step. If test light does not toggle on and off, go to step 23).
17. Check Light Blue wire for a poor connection at PCM. Repair as necessary. Go to step 36). If no problem is found, go to step 22).
18. Replace A/C pressure sensor. Go to step 36).
19. Repair open or poor connection in A/C pressure sensor ground circuit (Black wire). Go to step 36).
20. Disconnect A/C clutch relay. Using a test light connected to ground, probe A/C clutch relay battery and ignition feed circuits at A/C clutch relay connector. If test light illuminates at both circuits, go to step 24). If test light does not illuminate at both circuits, go to step 25).
21. Install A/C manifold gauge set. With ignition on, engine off, observe A/C high-side pressure readings on gauge set and scan tool. If high-side pressures are within 20 psi (1.4 kg/cm 2 ) of each other, diagnose A/C-heater system. See «A/C-HEATER SYSTEM - MANUAL»(ref-40621) article. If high-side pressures are not as specified, go to step 18).
22. Replace PCM. Go to step 36).
23. Repair A/C request signal circuit (Light Blue wire) from A/C selector switch. Go to step 36).
24. Connect a fused jumper wire between A/C clutch relay connector terminals No. 30 and 87. If compressor clutch engages, go to step 26). If compressor clutch does not engage, leave jumper wire installed and go to step 27).
25. If test light does not illuminate at battery feed terminal, check for a short to ground in compressor clutch battery feed circuit (Dark Green wire), or a faulty compressor clutch diode. Repair as necessary. Go to step 36). If no problem is found, go to step 28).
26. Remove jumper wire. Start engine and let idle. Using a test light connected to battery voltage, probe A/C clutch relay connector terminal No. 86 (Dark Green/White wire). Using scan tool, command A/C clutch relay on. If test light illuminates, go to step 11). If test light does not illuminate, go to step 29).
27. Disconnect compressor clutch harness connector. Using a test light connected to ground, probe Dark Green wire at compressor clutch harness connector. If test light illuminates, go to step 30). If test light does not illuminate, go to step 31).
28. Repair open in battery or ignition feed circuits to A/C clutch relay. Go to step 36).
29. Using a test light connected to ground, probe A/C clutch relay connector terminal No. 86 (Dark Green/White wire). If test light illuminates, go to step 32). If test light does not illuminate, go to step 33).
30. Using a test light connected to battery voltage, probe compressor clutch ground circuit (Black wire) at compressor clutch harness connector. If test light illuminates, go to step 34). If test light does not illuminate, go to step 35).
31. Repair open in compressor clutch battery feed circuit (Dark Green wire). Go to step 36).
32. Check A/C clutch relay control circuit (Dark Green/White wire) for a short to power. Repair as necessary. Go to step 36). If no problem is found, go to step 17).
33. Check A/C clutch relay control circuit (Dark Green/White wire) for an open or poor connection. Repair as necessary. Go to step 36). If no problem is found, go to step 17).
34. Replace compressor clutch coil. Go to step 36).
35. Repair open or poor connection in compressor clutch ground circuit (Black wire). Go to next step.
36. Start engine and let idle. Cycle A/C selector switch on and off. If compressor clutch cycles on and off, system is okay at this time. See DIAGNOSTIC AIDS. If operation is not as specified, go to step 2).

Diagnostic Aids

If DTC P0530 is set, do not perform this diagnostic procedure. Diagnose appropriate DTC before proceeding. See TESTS W/CODES article in ENGINE PERFORMANCE.

A/C refrigerant pressure less than 43 psi (3.0 kg/cm 2 ), or greater than 428 psi (30.1 kg/cm 2 ) will cause PCM to disable compressor clutch. With engine running and A/C on, use scan tool to monitor A/C high-side pressure for 2 minutes. If pressure is out of range, diagnose A/C-heater system. See A/C-HEATER SYSTEM - MANUAL article.

1. Before performing diagnosis, ensure A/C system is adequately charged. If A/C system is not adequately charged, evacuate and recharge system using approved refrigerant recovery/recycling equipment. If A/C system is adequately charged, go to next step.
2. Start engine and allow it to reach normal operating temperature. Turn A/C on. If compressor clutch engages, then disengages within 60 seconds, problem is not in compressor clutch. Diagnose A/C-heater system. See «A/C-HEATER SYSTEM - MANUAL»(ref-40621) article or in «A/C-HEATER SYSTEM - AUTOMATIC»(ref-40623) article. If operation is not as specified, go to next step.
3. Install scan tool. Turn A/C on. Monitor A/C REQUEST data on scan tool display. If display reads YES, go to next step. If display does not read YES, go to step 8).
4. Disconnect compressor clutch harness connector. Connect a test light between compressor clutch battery feed circuit (Dark Green wire) and ground circuit (Black wire) at compressor clutch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 12).
5. Check for faulty compressor clutch harness connector. Repair as necessary. Go to next step. If no problem is found, go to step 7).
6. Repair compressor clutch harness connector. Go to step 27).
7. Replace compressor clutch. Go to step 27).
8. Turn ignition off. Disconnect VCM harness connector C3. Turn ignition on. Using a test light connected to ground, probe A/C request signal circuit (Dark Green/White wire) at VCM harness connector C3. If test light illuminates, go to next step. If test light does not illuminate, go to step 11).
9. Check for poor connection at VCM harness connector C3. If a problem is found, go to next step. If no problem is found, go to step 26).
10. Repair VCM harness connector C3. Go to step 27).
11. Repair open or short to ground in Dark Green/White wire to A/C pressure switch and/or A/C control switch. Go to step 27).
12. Using a test light connected to ground, probe compressor clutch battery feed circuit (Dark Green wire) at compressor clutch harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 14).
13. Repair open in compressor clutch ground circuit (Black wire). Go to step 27).
14. Install scan tool. Turn ignition on, engine off. Using scan tool, command A/C clutch relay on. If A/C clutch relay energizes "clicks", go to step 23). If A/C clutch relay does not energize, go to next step.
15. Disconnect A/C clutch relay. Using a test light connected to ground, probe A/C clutch relay harness connector terminal No. 2. If test light illuminates, go to step 17). If test light does not illuminate, go to next step.
16. Repair open or short to ground in A/C clutch relay ignition feed circuit. Go to step 27).
17. Connect a test light between A/C clutch relay harness connector terminals No. 1 and No. 2 (Dark Green/White wire). Using scan tool, command A/C clutch relay on. If test light illuminates, go to next step. If test light does not illuminate, go to step 19).
18. Replace A/C clutch relay. Go to step 27).
19. Check for a faulty connection at VCM harness connector C3. If a problem is found, go to next step. If no problem is found, go to step 21).
20. Repair faulty connection at VCM harness connector C3. Go to step 27).
21. Check for an open in Dark Green/White wire between A/C clutch relay connector cavity No. 1 and VCM harness connector C3, terminal No. 1. If a problem is found, go to next step. If no problem is found, go to step 26).
22. Repair open in Dark Green/White wire between A/C clutch relay and VCM. Go to step 27).
23. Remove A/C clutch relay. Using a fused jumper wire, jumper terminals No. 3 (A/C clutch relay battery feed circuit) and No. 5 (compressor clutch battery feed circuit) together at A/C clutch relay connector. If compressor clutch engages, go to next step. If compressor clutch does not engage, go to step 25).
24. Replace A/C clutch relay. Go to step 27).
25. Repair open or short to ground in compressor clutch battery feed circuit (Dark Green wire). Go to step 27).
26. Replace VCM. Using required equipment, program new VCM and perform VTD password learn and CKP system variation learn procedures. Go to next step.
27. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not continue to run, go to step 2).
28. Allow engine to reach normal operating temperature. Using scan tool, retrieve DTCs. If any DTCs are set, diagnose as necessary. See TESTS W/CODES article in ENGINE PERFORMANCE. If no DTCs are set, go to next step.
29. Using scan tool, select CAPTURE INFO, REVIEW CAPTURE INFO. If any DTCs are displayed that have not been diagnosed, perform diagnosis for applicable DTC. See TESTS W/CODES article in ENGINE PERFORMANCE. If no DTCs are displayed, testing is complete.

A/C Compressor Clutch Control Circuit Wiring Diagram (With Manual A/C-Heater & 4.3L Engine). Scheme 1

A/C Compressor Clutch Control Circuit Wiring Diagram (With Automatic A/C). Scheme 2

A/C Compressor Clutch Control Circuit Wiring Diagram (2.2L Engine). Scheme 3