DTC B1452: Heating Expansion Valve Circuit/Open

DTC detecting condition:

When Heating expansion 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.

Courtesy of SUBARU OF AMERICA, INC.

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

CHECK CONNECTOR .
1. Check connecting condition of the A/C control panel connector, heat pump control module connector and Heating expansion 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 B1452 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 HARNESS (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect Heating expansion valve connector and heat pump control module connector.
3. Using a tester, measure the resistance between the Heating expansion valve connector and heat pump control module connector.
  Connector and terminal
  
  (B660) No. 1 - (i365) No. 15:
  
  (B660) No. 4 - (i365) No. 16:
  
  (B660) No. 5 - (i365) No. 35:
  
  (B660) No. 2 - (i365) No. 36:
Is the resistance less than 1 Ω?

Yes: Go to 3.

No: Repair or replace the open circuit of harness.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
Using a tester, measure the resistance between Heating expansion valve connector and chassis ground.

Connector and terminal

(B660) No. 1 - Chassis ground:

(B660) No. 4 - Chassis ground:

(B660) No. 5 - Chassis ground:

(B660) No. 2 - Chassis ground:

Is the resistance 10 kΩ or more?

Yes: Go to 4.

No: Repair or replace the short circuit of the harness.
CHECK HEAT PUMP CONTROL MODULE .
Using a tester, measure the voltage between the heat pump control module connector and chassis ground.

Connector and terminal

(i365) No. 40 (+) - Chassis ground (-):

Is the voltage 11 - 14 V?

Yes: Go to 5.

No: Repair or replace the open, short circuit of the harness.
CHECK Heating expansion valve .
1. Connect the Heating expansion valve connector.
2. Using a tester, measure the resistance between Heating expansion valve connector terminals. (20°C)
  Connector and terminal
  
  (B660) No. 1 - (B660) No. 4:
  
  (B660) No. 2 - (B660) No. 5:
Is the resistance 8 - 10 Ω?

Yes: Go to 6.

No: Replace Heating expansion valve. Ref. to AIR CONDITIONER (HEV)>EXPANSION VALVE .
CHECK Heating expansion valve .
Using a tester, measure the resistance between Heating expansion valve connector terminals. (20°C)

Connector and terminal

(B660) No. 1 - (B660) No. 2:

(B660) No. 4 - (B660) No. 5:

Is the resistance 0 Ω?

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

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