Inspection Procedure 12

INSPECTION PROCEDURE 12: Rear Blower Fan and Motor Do Not Turn.

Rear Blower Motor Circuit (Part 1):

Rear Blower Motor Circuit (Part 2):

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

TROUBLESHOOTING HINTS
- Malfunction of the rear blower relay
- Malfunction of the resistor
- Malfunction of the rear blower motor
- Malfunction of the A/C-ECU
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

DIAGNOSIS

Required Special Tools:
- MB991223: Test Harness Set
- MB992006: Extra Fine Probe

STEP 1. Check rear blower motor connector C-20 for damage.






Q: Is rear blower motor connector C-20 in good condition?

YES : Go to Step 2.

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

STEP 2. Measure the voltage at rear blower motor connector C-20.






1. Disconnect rear blower motor connector C-20, and measure the voltage at the wiring harness side.
2. Turn the ignition switch to the "ON" position.
3. Turn the blower speed selection dial to the "MAX" position.
4. Turn the mode selection dial to the "Face" position.
5. Turn the rear blower switch to the "ON" position.






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

Q: Is the measured voltage approximately 12 V?

YES : Go to Step 13.

NO : Go to Step 3.

STEP 3. Check rear blower relay connector C-209 for loose, corroded or damaged terminals, or terminals pushed back in the connector.






Q: Is rear blower relay connector C-209 in good condition?

YES : Go to Step 4.

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

STEP 4. Check the rear blower relay continuity.






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






Q: Is the rear blower relay in good condition?

YES : Go to Step 5.

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

STEP 5. Measure the voltage at rear blower relay connector C-209.






1. Disconnect rear blower relay connector C-209, and measure the voltage at the junction block side.
2. Turn the ignition switch to the "ON" position.
3. Turn the blower speed selection dial to the "MAX" position.
4. Turn the mode selection dial to the "Face" position.
5. Turn the rear blower switch to the "ON" position.






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

Q: Is the measured voltage approximately 12 V?

YES : Go to Step 8.

NO : Go to Step 6.

STEP 6. Check A/C-ECU connector C-16 for loose, corroded or damaged terminals, or terminals pushed back in the connector.






Q: Is A/C-ECU connector C-16 in good condition?

YES : Go to Step 7.

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

STEP 7. Check the wiring harness between A/C-ECU connector C-16 (terminal 7) and rear blower relay connector C-209 (terminal 3).












NOTE: Also check joint connector C-103 and junction block connector C-213 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If joint connector C-103 is damaged, repair or replace the connector.
- Check the A/C-ECU lines for open circuit and short circuit.

Q: Is the wiring harness between A/C-ECU connector C-16 (terminal 7) and rear blower relay connector C-209 (terminal 3) in good condition?

YES : Replace the A/C-ECU, and check that the rear blower motor should operate normally.

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

STEP 8. Measure the voltage at rear blower relay connector C-209.






1. Disconnect rear blower relay connector C-209, and measure the voltage at the junction block side.






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

Q: Is the measured voltage approximately 12 V?

YES : Go to Step 10.

NO : Go to Step 9.

STEP 9. Check the wiring harness between rear blower relay connector C-209 (terminal 4) and fusible link (1).












NOTE: Also check junction block connector C-213 and intermediate connector C-31. If intermediate connector C-31 is damaged, repair or replace the connector.
- Check the rear blower relay power supply line for open circuit.

Q: Is the wiring harness between rear blower relay connector C-209 (terminal 4) and fusible link (1) in good condition?

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

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

STEP 10. Measure the resistance at rear blower relay connector C-209 in order to the ground circuit to the rear blower relay.






1. Disconnect rear blower relay connector C-209, and measure at the junction block 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 12.

NO : Go to Step 11.

STEP 11. Check the wiring harness between rear blower relay connector C-209 (terminal 2) and the ground.









NOTE: Also check junction block connector C-213 and joint connector C-103. If joint connector C-103 is damaged, repair or replace the connector.
- Check the rear blower relay ground line for open circuit.

Q: Is the wiring harness between rear blower relay connector C-209 (terminal 2) and the ground in good condition?

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

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

STEP 12. Check the wiring harness between rear blower motor connector C-20 (terminal 3) and rear blower relay connector C-209 (terminal 1).









NOTE: Also check intermediate connector C-24 and junction block connector C-213 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-24 or junction block connectors C-213 is damaged, repair or replace the connector.
- Check the rear blower motor power supply line for open circuit.

Q: Is the wiring harness between rear blower motor connector C-20 (terminal 3) and rear blower relay connector C-209 (terminal 1) in good condition?

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

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

STEP 13. Check the rear blower fan and motor operation.






1. Disconnect rear blower motor connector C-20.






2. When battery voltage is applied between the terminals 1 and 3, check that the motor operates. Also, check that there is no abnormal noise.

Q: Is the check result satisfactory?

YES : Replace the rear blower relay. The rear blower motor should operate normally.

NO : Go to Step 14.

STEP 14. Check floor console rear A/C switch assembly connector C-19 for damage.






Q: Is floor console rear A/C switch assembly connector C-19 in good condition?

YES : Go to Step 15.

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

STEP 15. Check the floor console rear A/C switch assembly operation.






1. Disconnect floor console rear A/C switch assembly connector C-19.






2. Follow the table below to check the floor console rear A/C switch assembly for continuity.






Q: Is the blower switch continuity in good condition?

YES : Go to Step 16.

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

STEP 16. Measure the resistance at floor console rear A/C switch assembly connector C-19 in order to the ground circuit to the rear blower motor.






1. Disconnect floor console rear A/C switch assembly connector C-19, and measure the voltage at the wiring harness side.






2. Measure the resistance value between terminal 3 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 18.

NO : Go to Step 17.

STEP 17. Check the wiring harness between floor console rear A/C switch assembly connector C-19 (terminal 3) and ground.






- Check the floor console rear A/C switch assembly ground line for open circuit.

Q: Is the wiring harness between floor console rear A/C switch assembly connector C-19 (terminal 3) and ground in good condition?

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

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

STEP 18. Check the wiring harness between rear blower motor connector C-20 (terminal 1) and floor console rear A/C switch assembly connector C-19 (terminal 5).






- Check the rear blower motor lines for open and short circuit.

Q: Is the wiring harness between rear blower motor connector C-20 (terminal 1) and floor console rear A/C switch assembly connector C-19 (terminal 5) in good condition?

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

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