INSPECTION PROCEDURE 4: The Blower Air Volume cannot be Changed










COMMENTS ON TROUBLE SYMPTOM


If air volume cannot be adjusted by using the blower control, the A/C control panel, the A/C-ECU or the power transistor may be faulty.

PROBABLE CAUSES



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

DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III CAN bus diagnostics


Use the M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?

Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C, Troubleshooting ).

STEP 2. M.U.T.-III diagnosis code


Check that the diagnosis code related to the air conditioner is not set.

Q. Is the diagnosis code set?

Carry out the diagnosis code procedures. Refer to .
Go to Step 3.

STEP 3. Connector check: C-121 power transistor controller connector


Q. Is the check result normal?

Go to Step 4.
Repair the connector.

STEP 4. Resistance measurement at the C-121 power transistor connector.


(1)Disconnect the connector, and measure at the wiring harness side.
(2)Continuity between terminal 1 and body earth
OK: Continuity exists (2 Ω or less)

Q. Is the check result normal?

Go to Step 5.
Repair the wiring harness wires between power transistor connector terminal No. 1 and body earth.

STEP 5. Connector check: C-111 A/C-ECU connector


Q. Is the check result normal?

Go to Step 6.
Repair the connector.

STEP 6. Check the wiring harness between C-115 blower motor connector terminal No.2 <LHD> or 1 <RHD> and C-111 A/C-ECU connector terminal No.1.



  • Check the blower motor earth line for open circuit.

Q. Is the check result normal?

Go to Step 7.
Repair the wiring harness.

STEP 7. Check the wiring harness between C-115 blower motor connector terminal No.4 and C-111 A/C-ECU connector terminal No.2.



  • Check the blower motor earth line for open circuit.

Q. Is the check result normal?

Go to Step 8.
Repair the wiring harness.

STEP 8. Replace the power transistor and check the trouble symptom


Check that the blower motor operates normally.

Q. Does the blower motor work normally?

This diagnosis is complete.
Replace the A/C-ECU.