A/C Compressor Clutch Circuit Troubleshooting
A/C Compressor Clutch Circuit TroubleshootingNOTE:
- It is normal for the A/C compressor to turn off under certain conditions, such as low idle, high engine coolant temperature, or hard acceleration.
- Do not use this troubleshooting procedure if the fans are also inoperative with the A/C on. Refer to the symptom troubleshooting index.
- Before doing any symptom troubleshooting, check for powertrain DTCs, R18A1 engine, K20Z3 engine.
1. Check the No. 20 (7.5 A) fuse in the under-hood fuse/relay box, and the No. 36 (10 A) fuse in the under-dash fuse/relay box.
Are the fuses OK?
YES - Go to step 2.
NO - Replace the fuses and recheck. If the fuses blow again, check for a short in the No. 20 (7.5 A) and No. 36 (10 A) fuses circuit.
2. Connect the HDS to the DTC.
3. Start the engine.
4. Turn on the A/C on the HVAC control unit.
5. Check the A/C CLUTCH in the PGM-FI Data List with the HDS.
Is the A/C CLUTCH on?
YES - Go to step 7.
NO - Go to step 6.
6. Check the engine coolant temperature and idle speed (use the HDS PGM-FI data list if possible).
Are the engine coolant temperature and idle speed OK?
YES - Go to step 7.
NO - Troubleshoot and repair the cause of the high engine coolant temperature, or low idle.
7. Remove the A/C compressor clutch relay from the under-hood fuse/relay box, and test it.
Is the relay OK?
YES - Go to step 8.
NO - Replace the A/C compressor clutch relay.
8. Measure the voltage between the A/C compressor clutch relay 4P socket terminal No.1 and body ground.
Is there battery voltage?
YES - Go to step 9.
NO - Replace the under-hood fuse/relay box.
9. Connect the A/C compressor clutch relay 4P socket terminals No.1 and No.2 with a jumper wire.
Does the A/C compressor clutch click?
YES - Go to step 10.
NO - Go to step 19.
10. Disconnect the jumper wire.
11. Turn the ignition switch ON (II).
12. Measure the voltage between the A/C compressor clutch relay 4P socket terminal No.3 and body ground.
Is there battery voltage?
YES - Go to step 13.
NO - Repair open in the wire between the No. 36 (10 A) fuse in the under-dash fuse/relay box and the A/C compressor clutch relay.
13. Turn the ignition switch OFF.
14. Reinstall the A/C compressor clutch relay.
15. Jump the SCS line with the HDS.
NOTE: This step must be done to protect the engine control module (ECM)/powertrain control module (PCM) from damage.
16. Disconnect ECM/PCM connector A (44P).
17. Connect the ECM/PCM connector A (44P) terminal No. 14 to body ground with a jumper wire.
18. Turn the ignition switch ON (II).
Does the A/C compressor click?
YES - Check for loose wires or poor connections at ECM/PCM connector A (44P). If the connections are good, check the ECM/PCM grounds. If the grounds are good, substitute a known-good ECM/PCM, and recheck. If the symptom/indication goes away, replace the original ECM/PCM, R18A1 engine, K20Z3 engine.
NO - Repair open in the wire between the A/C compressor clutch relay and the ECM/PCM.
19. Disconnect the jumper wire.
20. Disconnect the A/C compressor clutch 3P connector.
21. Check for continuity between the A/C compressor clutch relay 4P socket terminal No.2 and the A/C compressor clutch 3P connector terminal No.2.
Is there continuity?
YES - Check the A/C compressor clutch clearance, and the compressor clutch field coil. Repair as needed.
NO - Repair open in the wire between the A/C compressor clutch relay and the A/C compressor clutch.