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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 (see A/C SYSTEM INSPECTION )

  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 INSPECTION )

    NO  -Go to step 9

  9. Turn the ignition switch to LOCK (0)
  10. Jump the SCS line with the HDS
  11. Disconnect ECM/PCM connector A (49P)
  12. Turn the ignition switch to ON (II)
  13. Momentarily connect ECM/PCM connector terminal A15 to body ground with a jumper wire several times
    Fig 1: Connecting ECM/PCM Connector Terminal A15 To Body Ground With Jumper Wire
    G05992476Courtesy of AMERICAN HONDA MOTOR CO., INC.

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

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

    NO  -Check for poor connections or loose terminals at the A/C compressor clutch relay and the ECM/PCM If the connections are OK, check the A/C compressor clutch relay (see POWER RELAY TEST ) Then repair open in the wire between the ECM/PCM (A15) and the A/C compressor clutch relay and the other A/C systems