A/C Compressor Clutch Circuit Troubleshooting
- It is normal for the A/C compressor to turn off under certain conditions, such as low idle, high engine coolant temperature, hard acceleration, or high/low refrigerant pressure.
- Do not use this troubleshooting procedure if the fans are also inoperative with the A/C on. Refer to SYMPTOM TROUBLESHOOTING INDEX .
- Before doing any symptom troubleshooting, check for powertrain DTCs (see GENERAL TROUBLESHOOTING INFORMATION ).
- Check the No. 43 (7.5 A) and the No. 10 (7.5 A) fuses in the under-dash fuse/relay box.
Are the fuses OK?
YES - Go to step 2.
NO - Replace the blown fuses, and recheck. If either fuse blown again, check for a short in the No. 43 (7.5 A) or No. 10 (7.5 A) fuse circuits.
- Connect the HDS to the DLC.
- Start the engine.
- Turn on the A/C.
- 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.
- Check the engine coolant temperature and idle speed (use the HDS PGM-FI Data List if possible).TP SENSOR REFERENCE TABLE
TP sensor About 0.5 Vat idle RPM A/T 740-840 at idle M/T 700-800 at idle ECT sensor 2 176-212°F (80-100°C) Are the coolant temperature and idle speed OK?
YES - Go to A/C PRESSURE SWITCH CIRCUIT TROUBLESHOOTING .
NO - Troubleshoot and repair the cause of the high engine coolant temperature or low idle.
- Turn the ignition switch to LOCK (0).
- Remove the A/C compressor clutch relay from the auxiliary under-hood relay box, and test it (see POWER RELAY TEST
).
Is the relay OK?
YES - Go to step 9.
NO - Replace the A/C compressor clutch relay.
- Measure the voltage between A/C compressor clutch relay 4P socket terminal No. 1 and body ground.
Is there battery voltage?
YES - Go to step 10.
NO - Repair open in the wire between the No. 43 (7.5 A) fuse in the under-dash fuse/relay box and the A/C compressor clutch relay.
- Connect 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 11.
NO - Go to step 21.
- Disconnect the jumper wire.
- Turn the ignition switch to ON (II).
- Measure the voltage between A/C compressor clutch relay 4P socket terminal No. 4 and body ground.
Is there battery voltage?
YES - Go to step 14.
NO - Repair open in the wire between the No. 10 (7.5 A) fuse in the under-dash fuse/relay box and the A/C compressor clutch relay.
- Turn the ignition switch to LOCK (0).
- Reinstall the A/C compressor clutch relay.
- Make sure the A/C switch is OFF.
- Jump the SCS line with the HDS.NOTE: This step must be done to protect the engine/powertrain control module (ECM/PCM) from damage.
- Disconnect ECM/PCM connector A (49P).
- Connect the ECM/PCM connector A (49P) terminal No. 15 to body ground with a jumper wire.
- Turn the ignition switch to ON (II).
Does the A/C compressor click?
YES - Check for loose wires or poor connections at ECM/PCM connector A (49P). If the connections are good, substitute a known-good ECM/PCM, and recheck. If the symptom/indication goes away, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ).
NO - Repair open in the wire between the A/C. compressor clutch relay and the ECM/PCM.
- Disconnect the jumper wire.
- Disconnect the A/C compressor clutch 3P connector.
- Check for continuity between A/C compressor clutch relay 4P socket terminal No. 2 and A/C compressor clutch 3P connector terminal No. 2.
Is there continuity?
YES - Check the A/C compressor clutch clearance, the thermal protector circuit, and the A/C compressor clutch field coil (see A/C COMPRESSOR CLUTCH CHECK ).
NO - Repair open in the wire between the A/C compressor clutch relay and the A/C compressor clutch.