Air Goes Out Of Control. (Blower Motor Rotates At High Speed)

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

Trouble symptom:

The blower rotates even though the blower switch is not turned on.
The blower motor continues to rotate at high speed. (Not adjustable.)

Trouble causes:

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

Wiring diagram:

Air conditioning system Ref. to WIRING SYSTEM (CROSSTREK MODEL (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) (HEV)>GENERAL DESCRIPTION>CAUTION .

Courtesy of SUBARU OF AMERICA, INC.

CHECK A/C CONTROL PANEL .
1. Turn the ignition switch to ON.
2. Turn the fan dial to the maximum position.
3. Using the Subaru Select Monitor, check the following items in the [Data Monitor] of [Air Conditioner]. Ref. to AIR CONDITIONER (DIAGNOSTICS) (HEV)>DATA MONITOR .
  - Blower Fan Level
Does [Blower Fan Level] indicate "89 - 100"?

Yes : Go to 2.

No : Replace the A/C control panel. Ref. to AIR CONDITIONER (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) (HEV)>DATA MONITOR .
  - Blower Fan Level
Does [Blower Fan Level] indicate "1 - 17"?

Yes : Go to 3.

No : Replace the A/C control panel. Ref. to AIR CONDITIONER (HEV)>CONTROL PANEL .
CHECK HARNESS .
1. Turn the ignition switch to OFF.
2. Disconnect the power transistor connector.
3. Use a tester to measure the resistance between the power transistor connector and chassis ground.
  Connector & terminal
  
  (i183) No. 1 - Chassis ground:
Is the resistance less than 1 Ω?

Yes : Repair or replace the short circuit of the harness between blower motor and power transistor.

No : Go to 4.
CHECK HARNESS .
1. Remove the A/C control panel.
2. Turn the ignition switch to ON.
3. Use a tester to measure the resistance between the power transistor connector and chassis ground.
  Connector & terminal
  
  (i183) No. 4 - Chassis ground:
Is the resistance less than 1 Ω?

Yes : Repair or replace the short circuit of the harness between A/C control panel and power transistor.

No : Go to 5.
CHECK HARNESS .
1. Turn the ignition switch to OFF.
2. Connect the disconnected connectors.
3. Turn the ignition switch to ON.
4. Use a tester to measure the voltage between the power transistor connector and chassis ground.
  Connector & terminal
  
  (il83) No. 4 (+) - Chassis ground (-):
Is the voltage approx. 9.6 V when the fan dial is set to 1st, and approx. 2.7 V when set to 6th?

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

No : Go to 6.
CHECK A/C CONTROL PANEL .
1. Turn the ON/OFF switch to OFF.
2. Turn the ignition switch to OFF.
3. Disconnect the power transistor connector.
4. Turn the ignition switch to ON.
5. Use a tester to measure the resistance between the power transistor connector and chassis ground.
  Connector & terminal
  
  (i183) No. 4 - Chassis ground:
When the ON/OFF switch is OFF and ON, does the resistance change?

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

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