Air Does Not Come Out, Or Airflow Capacity Is Insufficient (Blower Motor Does Not Rotate)

WARNING: This page is about a different variant/trim than selected.

Trouble symptom:

Airflow capacity is insufficient.
Air does not come out when operating the fan dial.

Trouble causes:

Airflow capacity failure
CAN communication failure
A/C control panel failure
Blower motor failure

Wiring diagram:

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

Courtesy of SUBARU OF AMERICA, INC.

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

CHECK A/C CONTROL PANEL .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Air Conditioner]. Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)> DATA MONITOR .
  - Target air mix door actuator position (driver's side)
  - Target air mix door actuator position (passenger's side)
  - Blower Fan Level
3. 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 [Target air mix door actuator position (driver's side)] and [Target 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.
CHECK AIRFLOW CAPACITY .
Turn the temperature control dial to MAX COOL (both dials for the models equipped with left/right independent air conditioning function), A/C control panel fan dial to the maximum, 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 again.

NOTE: In this case, temporary poor contact of connector, temporary open or short circuit of harness may be the cause.
CHECK A/C FILTER .
Check the A/C filter. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> A/C FILTER .

Is the check result OK?

Yes: Go to 4.

No: Clean or replace the A/C filter. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> A/C FILTER .
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.
CHECK A/C CONTROL PANEL .
1. Turn the fan dial to the maximum position.
2. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Air Conditioner]. Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)> DATA MONITOR .
  - Blower Fan Level
  Does [Blower Fan Level] indicate "90 - 100"?
  
  Yes: Go to 6.
  
  No: Replace the A/C control panel. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> CONTROL PANEL .
CHECK A/C CONTROL PANEL .
1. Turn the fan dial to the minimum position.
2. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Air Conditioner]. Ref. to AIR CONDITIONER (DIAGNOSTICS) (EXCEPT FOR HEV)> DATA MONITOR .
  - Blower Fan Level
  Does [Blower Fan Level] indicate "1 - 16"?
  
  Yes: Go to 7.
  
  No: Replace the A/C control panel. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> CONTROL PANEL .
CHECK CONNECTOR .
Check for poor contact of connector.

Is the check result OK?

Yes: Go to 8.

No: Repair the connector.
CHECK FUSE .
1. Turn the ignition switch to OFF.
2. Remove the fuse No. 8 from fuse and relay box and the fuses No. 37 and No. 38 from the main fuse box.
3. Check the condition of fuse.
  Is the check result OK?
  
  Yes: Go to 9.
  
  No: Replace the fuse. If the replaced fuse blows out easily, repair the ground short circuit in harness between the pressure switch and fuse.
CHECK BLOWER MOTOR RELAY ON SIGNAL .
1. Turn the ignition switch to ON.
2. Turn the ON/OFF switch to OFF.
3. Using a tester, measure the voltage between the A/C control panel connector (i88) and chassis ground.
  Connector and terminal
  
  (i88) No. 28 (+) - Chassis ground (-):
  
  Is the voltage 10 V or more?
  
  Yes: Go to 10.
  
  No:
  - Check for open or short circuit in the harness between fuse and ECM.
  - Check the blower relay connector and relay unit. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> RELAY AND FUSE .
CHECK BLOWER MOTOR RELAY ON SIGNAL .
1. Start the engine.
2. Turn the ON/OFF switch to ON.
3. Using a tester, measure the voltage between the A/C control panel connector (i88) and chassis ground.
  Connector and terminal
  
  (i88) No. 28 (+) - Chassis ground (-):
  
  Is the voltage 0 V?
  
  Yes: Go to 11.
  
  No: Replace the A/C control panel Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> CONTROL PANEL .
CHECK BLOWER MOTOR POWER SUPPLY CIRCUIT .
1. Stop the engine.
2. Turn the ignition switch to ON.
3. Turn the ON/OFF switch to ON.
4. Use a tester to measure the voltage between the blower motor connector (il85) and chassis ground.
  Connector and terminal
  
  (il85) No. 2 (+) - Chassis ground (-):
  
  Is the voltage 10 V or more?
  
  Yes: Go to 12.
  
  No:
  - Check the blower motor power supply line harness for open circuit or connector disconnection.
  - Check the blower motor relay connector and relay unit. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> RELAY AND FUSE .
CHECK BLOWER MOTOR UNIT .
Check the blower motor Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> BLOWER MOTOR .

Is the check result of the blower motor OK?

Yes: Go to 13.

No: Replace the blower motor Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> BLOWER MOTOR .
CHECK HARNESS (OPEN CIRCUIT) .
1. Turn the ignition switch to OFF.
2. Disconnect the power transistor and A/C control panel connector.
3. Using a tester, measure the resistance between harness terminals.
  Connector and terminal
  
  (il83) No. 1 - (il85) No. 1:
  
  (il83) No. 4 - (i88) No. 38:
  
  0183) No. 3 - 088) No. 18:
  
  (i183) No. 2 - Chassis ground:
  
  Is the resistance less than 1 Ω?
  
  Yes: Go to 14.
  
  No: Repair or replace the open circuit of harness.
CHECK HARNESS (GROUND SHORT CIRCUIT) .
Use a tester to measure the harness resistance between the power transistor connector and chassis ground.

Connector and terminal

(i183) No. 4 - Chassis ground:

Is the resistance less than 1 Ω?

Yes: Repair or replace the short circuit of the harness.

No: Go to 15.
CHECK POWER TRANSISTOR .
Replace the power transistor with a properly functioning part.

Does the blower motor rotate?

Yes: Replace the power transistor Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> POWER TRANSISTOR .

No: Replace the A/C control panel. Ref. to AIR CONDITIONER (EXCEPT FOR HEV)> CONTROL PANEL .