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Home >> Subaru >> 2017 >> Forester 2.0XT Touring >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> HVAC System (Diagnostics) >> Diagnostics with Phenomenon >> Inspection >> Air Does Not Come Out, Or Airflow Capacity Is Insufficient

Air Does Not Come Out, Or Airflow Capacity Is Insufficient

Trouble symptom: 

Trouble causes: 

Wiring diagram: 

Air conditioning system Ref. to WIRING SYSTEM>Air Conditioning System>WIRING DIAGRAM .

Fig 1: Air Conditioning System Wiring Diagram (Insufficient Airflow Capacity)
G09483854Courtesy of SUBARU OF AMERICA, INC.
  1. CHECK A/C CONTROL PANEL. 
    1. Using Subaru Select Monitor, check the following data of the data monitor. Ref. to AIR CONDITIONER(DIAGNOSTICS)>Data Monitor .
      • Air mix door actuator position (driver's side)
      • Air mix door actuator position (passenger's side)
      • Blower Fan Level
    2. Turn the temperature control dial at MAX COOL and increase and decrease the A/C control panel fan dial. (For vehicles with left/right independent air conditioner, perform setting on both sides.)

    Do [Air mix door actuator position (driver's side)] and Air mix door actuator position (passenger's side) indicate "0%"? Also, does [Blower Fan Level] increase or decrease in accordance with the fan dial operation?

    • Yes  : Go to 2. 
    • No  : Go to   5  .
  2. CHECK AIRFLOW CAPACITY. 

    Turn the temperature control dial to LO (both dials for the models equipped with left/right independent air conditioning function), A/C control panel fan dial to MAX and FRESH/RECIRC switch to RECIRC.

    Is the airflow capacity insufficient for the same model?

    • Yes  : Go to 3. 
    • No  : 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 A/C FILTER. 

    Check the A/C filter.

    Is the check result OK?

    • Yes  : Go to 4. 
    • No  : Clean or replace the A/C filter.
  4. CHECK EACH DUCT. 

    Check each duct joint for disconnection or clogging.

    Is the check result OK?

    • Yes  : Go to 5. 
    • No  : Repair the faulty duct.
  5. CHECK A/C CONTROL PANEL. 
    1. Turn the ignition switch to ON.
    2. Turn the fan dial to the maximum position.
    3. Using Subaru Select Monitor, check [Blower Fan Level] of the data monitor. Ref. to AIR CONDITIONER(DIAGNOSTICS)>Data Monitor .

    Does [Blower Fan Level] indicate "7"?

  6. CHECK A/C CONTROL PANEL. 
    1. Turn the fan dial to the minimum position.
    2. Using Subaru Select Monitor, check [Blower Fan Level] of the data monitor.

    Does [Blower Fan Level] indicate "1"?

  7. CHECK CONNECTOR. 

    Check for poor contact of connector.

    Is the check result OK?

    • Yes  : Go to 8. 
    • No  : Repair the connector.
  8. CHECK FUSE. 
    1. Remove a fuse in the fuse & relay box.
    2. Check the condition of fuse.

    Is the check result OK?

    • Yes  : Go to 9. 
    • No  : Replace the fuse.
  9. CHECK BLOWER MOTOR RELAY ON SIGNAL. 
    1. Stop the engine.
    2. Turn the fan dial OFF.
    3. Turn the ignition switch to ON.
    4. Using a tester, measure the voltage between the A/C control panel connector (i88) and chassis ground.

      Connector & terminal 

      (i88) No. 9 (+) - Chassis ground (-):

    Is the voltage 10 V or more? 

    • Yes  : Go to 10. 
    • No  :
  10. CHECK BLOWER MOTOR RELAY ON SIGNAL. 
    1. Start the engine.
    2. Turn the fan dial to ON.
    3. Using a tester, measure the voltage between the A/C control panel connector (i88) and chassis ground.

      Connector & terminal 

      (i88) No. 9 (+) - Chassis ground (-):

    Is the voltage 0 V?

  11. CHECK BLOWER MOTOR POWER SUPPLY CIRCUIT. 
    1. Turn the ignition switch to ON.
    2. Turn the fan dial to ON.
    3. Use a tester to measure the voltage between the blower motor connector (B87) and chassis ground.

      Connector & terminal 

      (B87) No. 2 (+) - Chassis ground (-):

    Is the voltage 10 V or more?

  12. CHECK BLOWER MOTOR UNIT. 

    Check the blower motor. Ref. to HVAC SYSTEM (HEATER, VENTILATOR AND A/C)>Blower Motor>INSPECTION .

    Is the check result OK?

  13. CHECK HARNESS (OPEN CIRCUIT). 
    1. Disconnect the power transistor and A/C control panel connector.
    2. Using a tester, measure the resistance between harness terminals.

      Connector & terminal 

      (B386) No. 4 - (B57) No. 4:

      (B87) No. 1 - (B57) No. 3:

      (B57) No. 2 - (i88) No. 40:

      (B57) No. 1 - Chassis ground:

    Is the resistance less than 1 Ω?

    • Yes  : Go to 14. 
    • No  : Repair or replace the open circuit of harness.
  14. CHECK HARNESS (GROUND SHORT CIRCUIT). 

    Use a tester to measure the harness resistance between the power transistor connector and chassis ground.

    Connector & terminal 

    (B57) No. 2 - Chassis ground:

    Is the resistance less than 1 Ω?

    • Yes  : Repair or replace the short circuit of the harness.
    • No  : Go to 15. 
  15. CHECK POWER TRANSISTOR. 

    Replace the power transistor with a properly functioning part.

    Does the blower motor rotate?

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