HVAC Control Power, Ground, and Communication Circuit Troubleshooting
- Check the No. 36 (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. 36 (10 A) fuse circuit.
- Turn the ignition switch to ON (II).
- Measure the voltage between HVAC control unit connector B (16P) terminal No. 15 and body ground.Fig 1: Measuring Voltage Between HVAC Control Unit Connector B (16P) Terminal No. 15 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage?
YES -Go to step 4.
NO -Repair an open in the wire between the No. 36(10 A) fuse in the under-dash fuse/relay box and the HVAC control unit.
- Measure the voltage between HVAC control unit connector B (16P) terminal No. 4 and body ground.
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there less than 0.5 V?
YES -Go to step 5.
NO -Check for an open in the wire between the HVAC control unit and body ground. If the wire is OK, check for poor ground at G403 (see CONNECTOR TO FUSE/RELAY BOX INDEX ).
- Turn the ignition switch to LOCK (0).
- Disconnect HVAC control unit connector B (16P).
- Disconnect HVAC control unit connector A (24P).
- Check for continuity between the following terminals of the gauge control module 32P connector and HVAC control unit connector A (24P).
32P: 24P:
No. 19 No. 24
No. 20 No. 23
Fig 3: Checking Continuity Between Terminals Of Gauge Control Module 32P Connector And HVAC Control Unit Connector A (24P)Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES -Check for loose wires or poor connections at HVAC control unit connectors A (24P), and B (16P). If the connections are good, substitute a known-good HVAC control unit, and recheck. If the indication goes away, replace the original HVAC control unit (see HVAC CONTROL UNIT REMOVAL/INSTALLATION ).
NO -Repair an open in the wire between the HVAC control unit and the gauge control module.