## 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