HVAC - With A/C

HVAC DTC Troubleshooting: 2

DTC indicator 2: A Short in the Air Mix Control Motor Circuit

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

2. Do the self-diagnostic with the HVAC control unit. How To Troubleshoot The Heating and A/C Systems (With A/C)

3. Check for DTCs.

Is DTC 2 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


6. Disconnect the air mix control motor 7P connector.

7. Disconnect the HVAC control unit 24P connector.

8. Check for continuity between body ground and the HVAC control unit 24P connector terminals No. 1, 13, and 18 individually.

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

NO - Go to step 9.






9. Check for continuity between the HVAC control unit 24P connector terminals as follows.





Is there continuity between any of the terminals?
YES - Repair short in the wire(s).

NO - Go to step 10.


10. Turn the ignition switch to ON (II), and measure the same terminals for voltage between each terminal and body ground.

Is there battery voltage?
YES - Repair short to power in the wire(s) between the HVAC control unit and the air mix control motor. This short may also damage the HVAC control unit. Repair the short to power before replacing the HVAC control unit.

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