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 -

Do the A/C pressure sensor circuit troubleshooting B2979.�

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. Turn the ignition switch to ON (II).

12. 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 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 in the under-hood fuse/relay box and the PCM. If the connections and the terminals 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 or the other A/C parts.�