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 (see DTC B2979 OR PRE SENSOR OPEN IS INDICATED: AN OPEN IN THE A/C PRESSURE SENSOR CIRCUIT ).

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 (see 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.

Fig 1: Connecting PCM Connector Terminal A13 To Body Ground With Jumper Wire

Courtesy of AMERICAN HONDA MOTOR CO., INC.

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

YES  -Update the PCM if it does not have the latest software (see PCM UPDATE ), or substitute a known-good PCM (see SUBSTITUTING THE PCM ), then recheck. If the symptom/indication goes away with a known-good PCM, replace the original PCM (see PCM REPLACEMENT ).

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 (see 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.