Subaru Legacy BN/BS (2015-2019) Service Manual: Dtc b1440 air mix door actuator circuit open (driver)

Subaru Legacy BN/BS (2015-2019) Service Manual / Hvac system (diagnostics) / Diagnostic procedure with diagnostic trouble code (dtc) / Dtc b1440 air mix door actuator circuit open (driver)

DTC DETECTING CONDITION:

Air mix door actuator potentiometer circuit is open.

TROUBLE SYMPTOM:

• Temperature cannot be adjusted.

• Temperature of the driver’s side cannot be adjusted for model with left/right independent air conditioner.

WIRING DIAGRAM:

Air conditioning system Air Conditioning System > WIRING DIAGRAM

STEP	CHECK	YES	NO
1.CHECK CONNECTOR. 1) Check connecting condition of the A/C CM connector and air mix door actuator LH connector. 2) Read the DTC using Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)	Is B1440 displayed-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B1440 AIR MIX DOOR ACTUATOR CIRCUIT OPEN (DRIVER)	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 ACTUATOR. 1) Disconnect the air mix door actuator LH. 2) Short No. 3 and No. 5 of i174 connector. 3) Read the DTC using Subaru Select Monitor. Read Diagnostic Trouble Code (DTC)	Is B1442 displayed-	Replace the air mix door actuator LH. Air Mix Door Actuator > REMOVAL	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B1440 AIR MIX DOOR ACTUATOR CIRCUIT OPEN (DRIVER)
3.CHECK HARNESS. 1) Restore the temporary shorted lines made in step 2. 2) Turn the ignition switch to ON. 3) Using the tester, measure the voltage between terminals. Connector & terminal (i174) No. 1 (+) — No. 3 (−):	Is the voltage 4.5 — 5.0 V-	Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC B1440 AIR MIX DOOR ACTUATOR CIRCUIT OPEN (DRIVER)	Repair or replace the open circuit of harness.
4.CHECK HARNESS (OPEN CIRCUIT). 1) Disconnect the connector from A/C CM. 2) Using a tester, check continuity between terminals. Connector & terminal (i174) No. 1 — (i80) No. 12: (i174) No. 3 — (i181) No. 18: (i174) No. 5 — (i80) No. 17:	Is there continuity-	Replace the A/C CM. Control Unit > REMOVAL	Repair or replace the open circuit of harness.

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Other materials:

Diagnostics with phenomenon inspection
SymptomsFaulty partsEngine stalls when driving in “D” or “R” range, or selecting “N” > “D”, “N” > “R”.• Control valve• Engine control systemWhile driving in “D” range, vibration occurs immediately before ...