DTC B1450: Low-Pressure Solenoid Valve Circuit/Open

DTC detecting condition: 

When Low pressure solenoid valve circuit is faulty.

Trouble symptom: 

Compressor does not operate.

Wiring diagram: 

Air conditioning system Ref. to WIRING SYSTEM (CROSSTREK MODEL (HEV))>AIR CONDITIONING SYSTEM>WIRING DIAGRAM .

Courtesy of SUBARU OF AMERICA, INC.

1. CHECK CONNECTOR  .
   1. Check connecting condition of the A/C control panel connector, heat pump control module connector and Low pressure solenoid valve connector.
   2. Turn the ignition switch to ON.
   3. Read the DTC of [Air Conditioner] using the Subaru Select Monitor. Ref. to AIR CONDITIONER (DIAGNOSTICS) (HEV)> DIAGNOSTIC TROUBLE CODE (DTC) .

   Is DTC B1450 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 HEAT PUMP CONTROL MODULE  .
   1. Turn the ignition switch to OFF.
   2. Disconnect the heat pump control module connector.
   3. Using a tester, measure the voltage between the heat pump control module connector and chassis ground.

      Connector and terminal 

      (i365) No. 23 (+) - Chassis ground (-):

      Is the voltage 11 - 14 V?

   Yes:  Go to  3.

   No:  Go to  5.

3. CHECK Low pressure solenoid valve  .
   1. Disconnect the Low pressure solenoid valve connector. Ref. to AIR CONDITIONER (HEV)>SOLENOID VALVE .
   2. Using the tester, measure the resistance between Low pressure solenoid valve terminals.

      Connector and terminal 

      (B657) No. 1 - (B657) No. 2:

   Is the resistance 12.2 - 13.7 Ω?

   Yes:  Go to  4.

   No:  Replace Low pressure solenoid valve. Ref. to AIR CONDITIONER (HEV)>SOLENOID VALVE .

4. CHECK HARNESS (SHORTED BETWEEN LINES)  .

   Using a tester, measure the resistance between Low pressure solenoid valve connector terminals.

   Connector and terminal 

   (B657) No. 1 - (B657) No. 2:

   Is the resistance 10 kΩ or more?

   Yes:  Replace the heat pump control module. Ref. to AIR CONDITIONER (HEV)>CONTROL UNIT .

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

5. CHECK Low pressure solenoid valve POWER SUPPLY CIRCUIT  .
   1. Disconnect the Low pressure solenoid valve connector. Ref. to AIR CONDITIONER (HEV)>SOLENOID VALVE .
   2. Using a tester, measure the voltage between Low pressure solenoid valve connector terminals.

      Connector and terminal 

      (B657) No. 2 (+) - Chassis ground (-):

   Is the voltage 11 - 14 V?

   Yes:  Go to  6.

   No:  Repair or replace the open circuit of harness.

6. CHECK HARNESS (OPEN CIRCUIT)  .

   Using a tester, measure the resistance between the Low pressure solenoid valve connector and heat pump control module connector.

   Connector and terminal 

   (B657) No. 1 - (i365) No. 23:

   Is the resistance less than 1 Ω?

   Yes:  Go to  7.

   No:  Repair or replace the open circuit of harness.

7. CHECK HARNESS (GROUND SHORT CIRCUIT)  .

   Using a tester, measure the resistance between Low pressure solenoid valve connector and chassis ground.

   Connector and terminal 

   (B657) No. 1 - Chassis ground:

   Is the resistance 10 kΩ or more?

   Yes:  Replace Low pressure solenoid valve. Ref. to AIR CONDITIONER (HEV)>SOLENOID VALVE .

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