DTC B14EC: Humidity Sensor Circuit Open

DTC detecting condition: 

Temperature and humidity sensor circuit is open.

Trouble symptom: 

Proper outlet air temperature cannot be kept.

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 module connector and temperature and humidity sensor 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 B14EC displayed? (Current malfunction)

   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 again.

   NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
3. CHECK TEMPERATURE AND HUMIDITY SENSOR  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the temperature and humidity sensor.
   3. Short No. 2 and No. 3 in (i154) 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 B14ED displayed? (Current malfunction)

   Yes:  Replace the temperature and humidity sensor. Ref. to AIR CONDITIONER>TEMPERATURE AND HUMIDITY SENSOR .

   No:  Go to  4 .

4. CHECK HARNESS  .
   1. Turn the ignition switch to OFF.
   2. Restore the temporary shorted lines made in step 3.
   3. Turn the ignition switch to ON.
   4. Using a tester, measure the voltage between terminals in temperature and humidity sensor connector.

      Connector and terminal 

      (i154) No. 3 (+) - (i154) No. 2 (-):

   Is the voltage 4.5 - 5.5 V?

   Yes:  Go to  5 .

   No:  Repair or replace the open circuit of harness.

5. CHECK HARNESS (OPEN CIRCUIT)  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the connector from A/C control module.
   3. Using a tester, check the continuity between the A/C control module connector and temperature and humidity sensor connector.

      Connector and terminal 

      (i154) No. 2 - (i108) No. 7:

      (i154) No. 3 - (i107) No. 13:

   Is there continuity?

   Yes:  Replace the A/C control module. Ref. to AIR CONDITIONER>CONTROL UNIT .

   No:  Repair or replace the open circuit of harness.