HVAC Control Unit

Control System DTCs

HVAC DTC Troubleshooting: 3

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

1. Problem verification:

Problem verification
-1. Turn the ignition switch to LOCK (0), and then back to ON (II).

-2. Do the Self-Diagnostic Function with the HVAC control unit How to Troubleshoot the Heating and A/C Systems (Manual A/C).

-3. Check for DTCs.

Is DTC 3 indicated?
-YES- Go to step 2.
-NO- Intermittent failure. Check for loose wires or poor connections in the air mix control motor circuit.

2. Open wire check (M-HOT, M-COOL lines):

Open wire check (M-HOT, M-COOL lines)
-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the following connectors.





-3. Check for continuity between test points 1 and 2 respectively.














Is there continuity?
-YES- The M-HOT and M-COOL wires are OK. Go to step 3.
-NO- Repair an open in the wire(s) between the HVAC control unit and the air mix control motor.

3. Shorted wire check (M-HOT, M-COOL lines):

Shorted wire check (M-HOT, M-COOL lines)
-1. Check for continuity between test points 1 and 2 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- The M-HOT and M-COOL wires are OK. Go to step 4.

4. Air mix control motor check:

Air mix control motor check
-1. Test the air mix control motor Air Mix Control Motor Test.

Is the air mix control motor OK?
-YES- Replace the HVAC control unit HVAC Control Unit Removal and Installation (With Navigation).
-NO- Replace the air mix control motor Air Mix Control Motor Removal and Installation, or repair the air mix control linkage or door.