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Climate Control Unit Troubleshooting

WARNING: This page is about a different car, the 2009 Acura MDX, 2008 Acura MDX, and 2007 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check the No. 30 (10 A) fuse in the under-dash fuse/ relay box.

    Is the fuse OK? 

    YES  - Go to step 2.

    NO  - Replace the fuse, and recheck. If the fuse blows again, check for a short in the No. 30 (10 A) fuse circuit.

  2. Turn the ignition switch to ON (II).
  3. Measure the voltage between climate control unit connector A (40P) No. 3 terminal and body ground.
    Fig 1: Measuring Voltage Between Climate Control Unit Connector A (40P) No. 3 Terminal And Body Ground
    G05487664Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there battery voltage? 

    YES  - Go to step 4.

    NO  - Repair open in the wire between the No. 30 (10 A) fuse in the under-dash fuse/relay box and the climate control unit.

  4. Turn the ignition switch to LOCK (0).
  5. Check for continuity between climate control unit connector A (40P) No. 37 terminal and body ground.
    Fig 2: Identifying Continuity Between Climate Control Unit Connector A (40P) No. 37 Terminal And Body Ground
    G05487665Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Go to step 6.

    NO  - Check for an open in the wire between the climate control unit and body ground. If the wire is OK, check for poor ground at G506 (see GROUND TO COMPONENTS INDEX ).

  6. Disconnect climate control unit connector A (40P).
  7. Disconnect under-dash fuse/relay box connector X (39P).
  8. Check for continuity between under-dash fuse/relay box connector X (39P) No. 27 terminal and climate control unit connector A (40P) No. 4 terminal.
    Fig 3: Identifying Continuity Between Under-Dash Fuse/Relay Box Connector X (39P) No. 27 And No. 4 Terminal
    G05487666Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there continuity? 

    YES  - Check for loose wires and poor connections at climate control unit connector A (40P). If the connections are good, substitute a known-good climate control unit and recheck. If the symptom/ indication goes away, replace the original climate control unit.

    NO  - Repair open in the wire between the MICU and the climate control unit.