DTC B1438: Mode Door Actuator Circuit Open

DTC detecting condition: 

Mode door actuator potentiometer circuit is open.

Trouble symptom: 

Vent does not change.

Wiring diagram: 

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

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK CONNECTOR  .
   1. Turn the ignition switch to OFF.
   2. Check connecting condition of the A/C control panel connector and mode door actuator connector.

   Is the check result OK?

   Yes:  Go to  2.

   No:  Repair the connector.

2. CHECK DTC  .
   1. Turn the ignition switch to ON.
   2. Read the DTC of [Air Conditioner] using the Subaru Select Monitor. Ref. to AIR CONDITIONER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1438 displayed? (Current code)

   Yes:  Go to  3.

   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.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
3. CHECK ACTUATOR  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from the mode door actuator. Ref. to AIR CONDITIONER>MODE DOOR ACTUATOR>REMOVAL .
   3. Short No. 3 and No. 2 in (B146) connector.
   4. Turn the ignition switch to ON.
   5. Read the DTC of [Air Conditioner] using the Subaru Select Monitor. Ref. to AIR CONDITIONER (DIAGNOSTICS)>DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1439 displayed? (Current code)

   Yes:  Replace the mode door actuator. Ref. to AIR CONDITIONER>MODE DOOR ACTUATOR .

   No:  Go to  4.

4. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Restore the temporary shorted lines made in step 3.
   3. Disconnect the connector from the A/C control panel. Ref. to AIR CONDITIONER>CONTROL PANEL>REMOVAL .
   4. Using a tester, check the continuity between A/C control panel connector and mode door actuator connector terminals.

      Connector & terminal 

      (B146) No. 1 - (i130) No. 16:

      (B146) No. 2 - (i130) No. 33:

      (B146) No. 3 - (i130) No. 30:

   Is there continuity?

   Yes:  Replace the A/C control panel. Ref. to AIR CONDITIONER>CONTROL PANEL .

   No:  Repair or replace the open circuit of harness.