Inspection Procedure 5

INSPECTION PROCEDURE 5: Front Blower Fan And Motor Do Not Turn.

Blower Motor Circuit (Part 1):

Blower Motor Circuit (Part 2):

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

TROUBLESHOOTING HINTS
- Malfunction of the front blower relay
- Malfunction of the power transistor
- Malfunction of the front 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 and A/C-ECU connector C-15 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Are blower motor connector C-115 and A/C-ECU connector C-15 in good condition?

YES : Go to Step 2.

NO : Repair or replace the connector. 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. Disconnect A/C-ECU connector C-15 and ground harness side terminal No.9.
3. Turn the ignition switch to the "ON" position.







4. Measure the voltage between terminal 1 and ground.
- The measured value should be approx. 12 volts (battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES : Go to Step 11.

NO : Go to Step 3.

STEP 3. Check blower relay connector C-202 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is blower relay connector C-202 in good condition?

YES : Go to Step 4.

NO : Repair or replace the connector. The blower motor should operate normally.

STEP 4. Check the blower relay continuity.







Follow the table below to check the blower relay for continuity.







Q: Is the blower relay continuity in good condition?

YES : Go to Step 5.

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

STEP 5. Measure the voltage at blower relay connector C-202.







1. Disconnect blower relay connector C-202, and measure the voltage at the junction block side.
2. Turn the ignition switch to the "ON" position.







3. Measure the voltage between terminal 1 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES : Go to Step 7.

NO : Go to Step 6.

STEP 6. Check the wiring harness between blower relay connector C-202 (terminal 1) and the ignition switch (IG2).







NOTE: Also check junction block connector C-215 for loose, corroded, or damaged terminals, or terminals pushed back in the connector If junction block connector C-215 is damaged, repair or replace the connector.

- Check the relay power supply line for open circuit.

Q: Is the wiring harness between blower relay connector C-202 (terminal 1) and the ignition switch (IG2) in good condition?

YES : It can be assumed that this malfunction is intermittent.

NO : Repair the wiring harness. The blower motor should operate normally.

STEP 7. Measure the voltage at blower relay connector C-202.







1. Disconnect blower relay connector C-202, and measure the voltage at the junction block side.







2. Measure the voltage between terminal 5 and ground.
- The measured value should be approximately 12 volts (battery positive voltage).

Q: Is the measured voltage approx. 12 volts?

YES : Go to Step 9.

NO : Go to Step 8.

STEP 8. Check the wiring harness between blower relay connector C-202 (terminal 5) and fusible link (1).













NOTE: Also check intermediate connector C-29 and junction block connector C-216 for loose, corroded, or damaged terminals, or terminals pushed back in the connector If intermediate connector C-29, junction block connector C-216 is damaged, repair or replace the connector.

- Check the blower relay power supply open circuit.

Q: Is the wiring harness between blower relay connector C-202 (terminal 5) and fusible link (1) in good condition?

YES : It can be assumed that this malfunction is intermittent.

NO : Repair the wiring harness. The blower motor should operate normally.

STEP 9. Check the wiring harness between blower relay connector C-202 (terminal 3) and A/C-ECU connector C-15 (terminal 9).










NOTE: Also check junction block connector C-211 for loose, corroded, or damaged terminals, or terminals pushed back in the connector If junction block connector C-211 is damaged, repair or replace the connector.

- Check the blower relay power supply line for open circuit.

Q: Is the wiring harness between blower relay connector C-202 (terminal 3) and A/C-ECU connector C-15 (terminal 9) in good condition?

YES : Go to Step 10.

NO : Repair the wiring harness. The blower motor should operate normally.

STEP 10. Check the wiring harness between blower motor connector C-115 (terminal 1) and blower relay connector C-202 (terminal 4).










- Check the blower relay ground line for open circuit.

Q: Is the wiring harness between blower motor connector C-115 (terminal 1) and blower relay connector C-202 (terminal 4) in good condition?

YES : It can be assumed that this malfunction is intermittent.

NO : Repair the wiring harness. The blower motor should operate normally.

STEP 11. Check the blower fan and motor operation.







When battery voltage is applied between the terminals, check that the motor operates. Also, check that there is no abnormal noise.

Q: Is there any abnormal noise?

YES : Go to Step 12.

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

STEP 12. Check blower power transistor connector C-104 for loose, corroded or damaged terminals, or terminals pushed back in the connector.







Q: Is power transistor connector C-104 in good condition?

YES : Go to Step 13.

NO : Repair or replace the connector. The blower motor should operate normally.

STEP 13. Measure the resistance at power transistor connector C-104.







1. Disconnect power transistor connector C-104, and measure the resistance at the wiring harness side.







2. Measure the resistance value between terminal 2 and ground.
- The measured value should be 2 ohms or less.

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

YES : Go to Step 15.

NO: Go to Step 14.

STEP 14. Check the wiring harness between power transistor connector C-104 (terminal 2) and ground.







- Check the power transistor ground line for open circuit.

Q: Is the wiring harness between power transistor connector C-104 (terminal 2) and ground in good condition?

YES : It can be assumed that this malfunction is intermittent.

NO : Repair the wiring harness. The blower motor should operate normally.

STEP 15. Check the wiring harness between power transistor connector C-104 (terminal 4) and blower motor connector C-115 (terminal 2).







- Check the power transistor switch ground line for open circuit.

Q: Is the wiring harness between power transistor connector C-104 (terminal 4) and blower motor connector C-115 (terminal 2) in good condition?

YES : Go to Step 16.

NO : Repair the wiring harness. The blower motor should operate normally.

STEP 16. Check the wiring harness between power transistor connector C-104 (terminals 1 and 3) and A/C-ECU connector C-15 (terminals 17 and 18).







- Check the power transistor switch ground line for open circuit.

Q: Are the wiring harness between power transistor connector C-104 (terminals 1 and 3) and A/C-ECU connector C-15 (terminals 17 and 18) in good condition?

YES : Go to Step 17.

NO : Repair the wiring harness. The blower motor should operate normally.

STEP 17. Replace the power transistor.

Q: Does the blower motor operate normally?

YES : No action is necessary and testing is complete.

NO : Replace the A/C-ECU. Check that the A/C works normally.