HVAC - With A/C

HVAC DTC Troubleshooting: 2

DTC 2: A Problem in the Mode Control Motor Circuit

1. Disconnect the mode control motor 7P connector.

2. Test the mode control motor. Mode Control Motor Test

Is the mode control motor OK?
YES - Go to step 3.

NO - Go to step 7.


3. Disconnect the HVAC control unit 30P connector.

4. Check for continuity between body ground and HVAC control unit 30P connector terminals No. 3, 4, 8, 9, 10, 21, and 22 individually.

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

NO - Go to step 5.






5. Turn the ignition switch to ON (II), and measure the voltage between the same terminals and body ground.

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

NO - Go to step 6.






6. Turn the ignition switch to LOCK (0), and check for continuity between the following terminals of the HVAC control unit 30P connector and the mode control motor 7P connector.





Is there continuity?
YES - Check for loose wires or poor connections at the HVAC control unit 30P connector and at the mode control motor 7P connector. If the connections are good, substitute a known-good HVAC control unit , and recheck. If the symptom/indication goes away, replace the original HVAC control unit.

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






7. Remove the mode control motor. Mode Control Motor Replacement

8. Check the mode control linkage and doors for smooth movement.

Do the mode control linkage and doors move smoothly?
YES - Replace the mode control motor.

NO - Repair the mode control linkage or doors.