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.

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 clicking noise from the A/C compressor clutch?

YES - Go to the A/C section, and look for the other symptoms.n

NO - Go to 9.

9.Momentarily connect the A/C compressor clutch relay 4P connector (into the under-hood fuse/relay box) termminal No. 3 to body ground with a jumper wire several times.


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

YES - Repair open in the wire between the ECM connector No. 4 terminal No. 19 (test pin box terminal No. 100) and the A/C clutch relay.n

NO - Substitute a known-good ECM and recheck. If symptom/indication goes away, replace the original  ECM.n