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 A/C System Test.�

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 ECM connector A (44P).

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

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





Is there a clicking noise from the A/C compressor clutch?

YES -

Reconnect all connectors, and update the ECM if it does not have the latest software ECM/PCM Update, or substitute a known-good ECM, then recheck. If the symptom/indication goes away and the ECM was updated, troubleshooting is complete. If the symptom/indication goes away and the ECM was substituted, replace the original ECM Service and Repair.�

NO -

Check for poor connections or loose terminals at the A/C compressor clutch relay and the ECM. If the connections and the terminals are OK, check the A/C compressor clutch relay Testing and Inspection. If needed, repair open in the wire between the ECM (A14) and the A/C compressor clutch relay, and check other parts in the A/C systems.�