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 rear air mix door 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.

CAUTION: Before performing diagnosis, refer to "CAUTION" in "General Description". Ref. to AIR CONDITIONER (DIAGNOSTICS)>General Description>CAUTION .

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.
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 .
- Air mix door Actuator Target Open (Rear Seat)
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.
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 & terminal
  
  (AD47) No. 3 (+) - (AD47) No. 1 (-):
Is the voltage 4.5 - 5.5 V?

Yes : Go to 4.

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