HVAC - With A/C

HVAC DTC Troubleshooting: 3

DTC indicator 3: A Problem in the Air Mix Control Linkage, Door, or Motor

1. Turn the ignition switch to LOCK (0), and then turn it to ON (II).

2. Do the Self-diagnostic Function with the HVAC control unit. Reading and Clearing Diagnostic Trouble Codes

3. Check for DTCs.

Is DTC 3 indicated?
YES - Go to step 4.

NO - Intermittent failure. Check for damaged wires or poor connections in the air mix control motor circuit.


4. Turn the ignition switch to LOCK (0).

5. Test the air mix control motor. Air Mix Control Motor Test

Is the air mix control motor OK?
YES - Go to step 6.

NO - Replace the air mix control motor, Air Mix Control Motor Replacement or repair the air mix control linkage or door.


6. Check for continuity between following terminals of the HVAC control unit 24P connector and the air mix control motor 7P connector.





Is there continuity?
YES - Go to step 7.

NO - Repair an open in the wire(s) between the HVAC control unit and the air mix control motor.






7. Check for continuity between body ground and heater control panel 24P connector terminals No. 19 and No. 20 individually.

Is there continuity?
YES - Repair a short to body ground in the wire(s) between the HVAC control unit and the air mix control motor.

NO - Substitute a known-good HVAC control unit, and recheck. If the symptom/indication goes away, replace the original HVAC control unit.