HVAC - Without 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 with the heater control panel. How To Troubleshoot The Heating System (Without A/C)

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. Disconnect the air mix control motor 7P connector.

7. Disconnect the heater control panel 24P connector.

8. Check for continuity between the following terminals of the heater control panel 24P connector and the air mix control motor 7P connector.





Is there continuity?
YES - Go to step 9.

NO - Repair open in the wire(s) between the heater control panel and the air mix control motor.






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

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

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