A/C Signal Circuit Troubleshooting

A/C Signal Circuit Troubleshooting

1. Start the engine.

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 -

Check the A/C system Initial Inspection and Diagnostic Overview.

5. Check the A/C system operation.

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 (49P).

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

13. Momentarily connect PCM connector terminal A13 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, then recheck. If the symptom/indication goes away and the PCM was updated, troubleshooting is complete. If the symptom/indication goes away and the PCM was substituted, 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 Power Relay Test. If needed, repair an open in the wire between the PCM (A13) and the A/C compressor clutch relay and the other A/C system parts.