DTC B14D8: Air Mix Door Actuator Circuit Stuck (Rear HVAC)

DTC detecting condition: 

• Rear air mix door actuator is locked.
• The potentiometer value of the actuator does not change.

Trouble symptom: 

Temperature cannot be adjusted.

Wiring diagram: 

Air conditioning system. Ref. to WIRING SYSTEM>AIR CONDITIONING SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK CONNECTOR. 
   1. Check connecting condition of the A/C Control Module connector and rear air mix door actuator.
   2. Read the DTC of [Air Conditioner] using the Subaru Select Monitor. Ref. to AIR CONDITIONER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B14D8 displayed? (Current malfunction)

   Yes  : Go to  2.

   No  : Even if DTC is displayed, the circuit has returned to a normal condition at this time.

   Reproduce the failure, and then perform the diagnosis again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
2. CHECK ACTUATOR. 

   Using the Subaru Select Monitor, check the following items in the [Active Test] of [Air Conditioner]. Ref. to AIR CONDITIONER (DIAGNOSTICS)>ACTIVE TEST .

   • [Rear air mix door actuator target opening angle]

   Did the rear air mix door actuator move to the specified target opening angle?

   Yes  : Rear air mix door actuator circuit is normal.

   No  : Go to  3.

3. CHECK HARNESS. 
   1. Turn the ignition switch to ON.
   2. Using a tester, measure the voltage between rear air mix door actuator connector terminals.

      Connector and terminal 

      (AD47) No. 3 (+) - (AD47) No. 1 (-):

   Is the voltage 4.5 - 5.0 V?

   Yes  : Go to  4.

   No  : Repair or replace the open, short circuit of the harness.

4. CHECK HARNESS (OPEN CIRCUIT). 
   1. Disconnect the connector from A/C Control Module.
   2. Using a tester, check the continuity between A/C Control Module connector and rear air mix door actuator connector terminals.

      Connector and terminal 

      (AD47) No. 3 - (i329) No. 12:

      (AD47) No. 1 - (i329) No. 24:

      (AD47) No. 2 - (i80) No. 26:

      (AD47) No. 5 - (i329) No. 20:

      (AD47) No. 4 - (i329) No. 30:

   Is there continuity?

   Yes  : Go to  5.

   No  : Repair or replace the open circuit of harness.

5. CHECK AIR MIX DOOR ACTUATOR. 

   Check the rear air mix door actuator parts. Ref. to AIR CONDITIONER>AIR MIX DOOR ACTUATOR .

   Is rear air mix door actuator normal?

   Yes  : Replace the A/C Control Module. Ref. to AIR CONDITIONER>CONTROL UNIT .

   No  : Replace the rear air mix door actuator. Ref. to AIR CONDITIONER>AIR MIX DOOR ACTUATOR .