Inspection Procedure 4

INSPECTION PROCEDURE 4: Blower Fan and Motor do not Turn.










CIRCUIT OPERATION

If the blower motor does not operate, the blower relay system is suspected.

TROUBLESHOOTING HINTS

- Malfunction of the power transistor
- Malfunction of the blower motor
- Malfunction of the A/C-ECU
- Damaged harness wires or connectors

DIAGNOSIS

Required Special Tools:

- MB991223: Harness Set
- MB992006: Extra Fine Probe

STEP 1. Check blower motor connector C-115 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is blower motor connector C-115 in good condition?

YES Go to Step 2.
NO Repair or replace the connector. Harness Connector Inspection.The blower motor should operate normally.
STEP 2. Measure the voltage at blower motor connector C-115.

(1)Disconnect blower motor connector C-115, and measure the voltage at the wiring harness side.

(2)Turn the ignition switch to the "ON" position.

(3)Turn the blower switch to the "Maximum air volume" position.





(4)Measure the voltage between terminal 1 and ground.

- The measured value should be approximately 12 volts (battery positive voltage).

Q. Is the measured voltage approximately 12 volts?

YES Go to Step 3.

NO Refer to Inspection procedure 9, "Blower motor power supply system Inspection Procedure 9."

STEP 3. Check blower motor connector C-115 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is blower motor connector C-115 in good condition?

YES Go to Step 4.
NO Repair or replace the connector. Harness Connector Inspection.The blower motor should operate normally.
STEP 4. Check the blower fan and motor operation.





Check that the motor turns when applying battery power between the connector terminals.
Also check to see that there is no abnormal sound emitted from the motor at this time..

Q. Is there any abnormal noise?

YES Go to Step 5.

NO Replace the blower relay. The blower motor should operate normally.

STEP 5. Check A/C-ECU connector C-22 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is A/C-ECU connector C-22 in good condition?

YES Go to Step 6.
NO Repair or replace the connector. Harness Connector Inspection.The blower motor should operate normally.
STEP 6. Check the wiring harness between A/C-ECU connector C-22 (terminal 1) and blower motor connector C-115 (terminal 2).

- Check the A/C-ECU signal line for open and short circuit.

Q. Is the wiring harness between A/C-ECU connector C-22 (terminal 1) and blower motor connector C-115 (terminal 2) in good condition?

YES Go to Step 7.
NO Repair the wiring harness. The blower motor should operate normally.
STEP 7. Check power transistor connector C-119 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is power transistor connector C-119 in good condition?

YES Go to Step 8.
NO Repair or replace the connector. Harness Connector Inspection.The blower motor should operate normally.
STEP 8. Measure the resistance at power transistor connector C-119.

(1)Disconnect power transistor connector C-119, and measure the resistance at the wiring harness side.





(2)Measure the resistance value between terminal 1 and ground.
OK: The measured value should be 2 ohms or less

Q. Does the measured resistance value correspond with this range?

YES Go to Step 10.

NO Go to Step 9.

STEP 9. Check the wiring harness between power transistor connector C-119 (terminal 1) and ground.

- Check the power transistor ground line for open circuit.

Q. Is the wiring harness between power transistor connector C-119 (terminal 1) and ground in good condition?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
NO Repair the wiring harness. The blower motor should operate normally.
STEP 10. Check the wiring harness between A/C-ECU connector C-22 (terminals 1 and 2) and power transistor connector C-119 (terminals 2 and 4).

- Check the A/C-ECU signal line for open and short circuit.

Q. Is the wiring harness between A/C-ECU connector C-22 (terminals 1 and 2) and power transistor connector C-119 (terminals 2 and 4) in good condition?

YES Go to Step 11.
NO Repair the wiring harness. The blower motor should operate normally.
STEP 11. Replace the power transistor and check the trouble symptom again

Check the trouble symptom again.

Q. Is the check result satisfactory?

YES The procedure is complete.
NO Replace the A/C-ECU.