Inspection Procedure 4: The blower air volume cannot be changed












COMMENTS ON TROUBLE SYMPTOM
If the blower air volume can not be changed when the blower switch is operated, the circuit between front power transistor and A/C-ECU may be defective.

PROBABLE CAUSES

  • Malfunction of the power transistor
  • Damaged the wiring harness or connectors
  • Malfunction of the automatic A/C control panel (A/C-ECU)

DIAGNOSIS PROCEDURE

STEP 1. Connector check: D-116 power transistor controller connector

Q. Is the check result normal?
Go to Step 2.
Repair the connector.

STEP 2. Resistance measurement at the D-116 power transistor connector.
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Continuity between terminal 4 and body earth
OK: Continuity (Less than 2 ohms)

Q. Is the check result normal?
Go to Step 4.
Go to Step 3.

STEP 3. Check the wiring harness between D-116 power transistor connector terminal No.4 and body earth.

  • Check the blower linear controller earth line for open circuit.

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Repair the wiring harness.

STEP 4. Connector check: D-08 A/C-ECU controller connector

Q. Is the check result normal?
Go to Step 5.
Repair the connector.

STEP 5. Check the wiring harness between D-08 A/C-ECU connector terminal 11 and D-116 power transistor controller connector terminal 3).

  • Check the power transistor power supply line for open circuit.

Q. Is the check result normal?
Go to Step 6.
Repair the wiring harness.

STEP 6. Replace the front power transistor and check the trouble symptom
Check that the front blower motor operates normally.

Q. Does the blower motor work normally?

This diagnosis is complete.
Replace the automatic A/C control panel (A/C-ECU).