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.

Is it ON?

YES - Go to 5.

NO - Go to the A/C pressure switch circuit troubleshooting.n

5.Check the A/C system.

Does the A/C system operate?

YES - The air conditioning system circuit is OK.n

NO - Go to 6.

6.Turn the ignition switch OFF.

7.Turn the ignition switch 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.n

NO - Go to 9.

9.Momentarily connect under-hood fuse/relay box 14P connector terminal No. 10 to body ground with a jumper wire several times.


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

YES - Repair open in the wire between the ECM/PCM (E18) and the A/C clutch relay.n

NO - Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck. If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.n