A/C Signal Circuit Troubleshooting

A/C Signal Circuit Troubleshooting

1. Start the engine, and let it idle.

2. Turn the blower switch on.

3. Turn the A/C switch on.

4. Check the A/C CLUTCH in the DATA LIST with the HDS.

Does it indicate ON?
YES - Go to step 5.

NO - Do the A/C system test. Service and Repair


5. Check the A/C system.

Does the A/C system operate?
YES - The air conditioning system circuit is OK.

NO - Go to step 6.


6. Turn the ignition switch to LOCK (0).

7. Turn the ignition switch to ON (II).

8. Activate the A/C CLUTCH in the INSPECTION MENU with the HDS.

Is there a clicking noise from the A/C compressor clutch?
YES - Do the A/C system test. A/C System Test

NO - Go to step 9.


9. Turn the ignition switch to LOCK (0).

10. Jump the SCS line with the HDS.

11. Disconnect PCM connector A (44P).

12. Turn the ignition switch to ON (II).

13. Momentarily connect PCM connector terminal A14 to body ground with a jumper wire several times.

Is there a clicking noise from the A/C compressor clutch?
YES - Update the PCM if it does not have the latest software, PCM Update or substitute a known-good PCM, Initial Inspection and Diagnostic Overview then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM. Service and Repair

NO - Check for poor connections or loose terminals at the A/C compressor clutch relay and the PCM. If the connections are OK, check the A/C compressor clutch relay, Testing and Inspection then repair open in the wire between the PCM (A14) and the A/C compressor clutch relay and the other A/C systems.