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A/C Compressor Clutch Circuit Troubleshooting

WARNING: This page is about a different car, the 2006 Acura MDX, 2005 Acura MDX, 2004 Acura MDX, and 2003 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
  • Do not use this troubleshooting procedure if the fans are also inoperative. Refer to the symptom troubleshooting index.
  • Before doing symptom troubleshooting, check for powertrain DTCs (see GENERAL TROUBLESHOOTING INFORMATION ).
  1. Check the No. 59 (7.5 A) fuse in the underhood fuse/relay box, and the No. 3 (7.5 A) fuse in the driver's underdash fuse/relay box.

    Are the fuses OK? 

    1. YES  - Go to step 2.
    2. NO  - Replace the fuse(s), and recheck.
  2. Check the engine coolant temperature, throttle position, and idle speed (use the HDS PGM-FI data list, if possible).
    ENGINE COOLANT TEMPERATURE CHECK

    ECT Sensor 144-169 °F (76-90 °C)
    TP Sensor About 0.5 V
    RPM More than 730

    Are the coolant temperature, throttle position, and idle speed OK? 

    1. YES  - Go to step 3.
    2. NO  - Troubleshoot and repair the cause of the high engine coolant temperature, low idle, or excessively high throttle position sensor reading.
  3. Remove the A/C compressor clutch relay from the underhood fuse/relay box, and test it (see POWER RELAY TEST ).

    Is the relay OK? 

    1. YES  - Go to step 4.
    2. NO  - Replace the A/C compressor clutch relay.
  4. Measure the voltage between the No.1 terminal of the A/C compressor clutch relay 4P socket and body ground.
    Fig 1: Measuring Voltage Between No.1 Terminal Of A/C Compressor Clutch Relay 4P Socket And Body Ground
    G03641872Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step 5.
    2. NO  - Replace the underhood fuse/relay box.
  5. Connect the No. 1 and No. 2 terminals of the A/C compressor clutch relay 4P socket with a jumper wire.
    Fig 2: Connecting No. 1 And No. 2 Terminals Of A/C Compressor Clutch Relay 4P Socket With Jumper Wire
    G03641873Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Does the A/C compressor clutch click? 

    1. YES  - Go to step 6.
    2. NO  - Go to step  19.
  6. Disconnect the jumper wire.
  7. Turn the ignition switch ON (II).
  8. Measure the voltage between the No. 4 terminal of the A/C compressor clutch relay 4P socket and body ground.
    Fig 3: Measuring Voltage Between No. 4 Terminal Of A/C Compressor Clutch Relay 4P Socket And Body Ground
    G03641874Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step 9.
    2. NO  - Repair open in the wire between the No. 3 fuse in the driver's underdash fuse/relay box and the A/C compressor clutch relay.
  9. Turn the ignition switch OFF.
  10. Reinstall the A/C compressor clutch relay.
  11. Make sure the A/C switch is OFF.
  12. Jump the SCS line with the HDS.
  13. Turn the ignition switch OFF.
  14. Disconnect PCM connector B (56P).
  15. Turn the ignition switch ON (II).
  16. Measure the voltage between the No. 11 terminal of PCM connector B (56P) and body ground.
    Fig 4: Measuring Voltage Between No. 11 Terminal Of PCM Connector B (56P) And Body Ground
    G03641875Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    1. YES  - Go to step 17.
    2. NO  - Repair open in the wire between the A/C compressor clutch relay and the PCM.
  17. Disconnect the A/C pressure switch 4P connector.
  18. Check for continuity between the No. 56 terminal of PCM connector B (56P) and No. 1 terminal of the A/C pressure switch 4P connector.
    Fig 5: Checking For Continuity Between No. 56 Terminal Of PCM Connector B
    G03641876Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Check for loose wires or poor connections at PCM connector B (56P). If the connections are good, substitute a known-good PCM, and recheck. If the symptom/indication goes away, replace the original PCM.
    2. NO  - Repair open in the wire between the PCM and the A/C pressure switch.
  19. Disconnect the jumper wire.
  20. Disconnect the A/C compressor clutch 1P connector.
  21. Check for continuity between the No. 2 terminal of the A/C compressor clutch relay 4P socket and the No. 1 terminal of the A/C compressor clutch 1P connector.
    Fig 6: Checking For Continuity Between No. 2 Terminal Of A/C Compressor Clutch Relay 4P Socket
    G03641877Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    1. YES  - Check the A/C compressor clutch clearance and the A/C compressor clutch field coil (see A/C COMPRESSOR CLUTCH CHECK  ).
    2. NO  - Repair open in the wire between the A/C compressor clutch relay and the A/C compressor clutch.
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