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 resistor
- 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 front blower motor connector C-111 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is front blower motor connector C-111 in good condition?
YES : Go to Step 2.
NO : Repair or replace the connector. The front blower motor should operate normally.
STEP 2. Measure the voltage at front blower motor connector C-111.
1. Disconnect front blower motor connector C-111, 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 "4 (HI)" 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 15.
NO : Go to Step 3.
STEP 3. Check front blower relay connector C-202 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is front blower relay connector C-202 in good condition?
YES : Go to Step 4.
NO : Repair or replace the connector. The front blower motor should operate normally.
STEP 4. Check the front blower relay continuity.
Follow the table below to check the front blower relay for continuity.
Q: Is the front blower relay continuity in good condition?
YES : Go to Step 5.
NO : Replace the front blower relay. The front blower motor should operate normally.
STEP 5. Measure the voltage at front blower relay connector C-202.
1. Disconnect front 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 front 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 front blower relay power supply line for open circuit.
Q: Is the wiring harness between front 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 front blower motor should operate normally.
STEP 7. Measure the voltage at front blower relay connector C-202.
1. Disconnect front 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 front blower relay connector C-202 (terminal 5) and fusible link (1).
NOTE: Also check intermediate connector C-31 and junction block connector C-216 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-31, junction block connector C-216 is damaged, repair or replace the connector.
- Check the front blower relay power supply line for open circuit.
Q: Is the wiring harness between front 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 front blower motor should operate normally.
STEP 9. Measure the resistance at front blower relay connector C-202.
1. Disconnect front blower relay connector C-202, and measure the resistance 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 11.
NO: Go to Step 10.
STEP 10. Check the wiring harness between front blower relay connector C-202 (terminal 3) and ground.
NOTE: Also check junction block connector C-211 and joint connector C-103 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If junction block connector C-211 and joint connector C-103 is damaged, repair or replace the connector.
- Check the front blower relay ground line for open circuit.
Q: Is the wiring harness between front blower relay connector C-202 (terminal 3) and ground in good condition?
YES : It can be assumed that this malfunction is intermittent.
NO : Repair the wiring harness. The front blower motor should operate normally.
STEP 11. Check blower switch connector C-41 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is blower switch connector C-41 in good condition?
YES : Go to Step 12.
NO : Repair or replace the connector. The blower motor should operate normally.
STEP 12. Check the blower switch continuity.
Follow the table below to check the blower switch for continuity.
Q: Is the blower switch continuity in good condition?
YES : Go to Step 13.
NO : Replace the blower switch. The blower motor should operate normally.
STEP 13. Check the wiring harness between blower motor connector C-111 (terminal 1) and blower switch connector C-41 (terminal 5).
- Check the front blower switch ground line for open circuit.
Q: Is the wiring harness between blower motor connector C-111 (terminal 1) and blower relay connector C-41 (terminal 5) in good condition?
YES : Go to Step 14.
NO : Repair the wiring harness. The blower motor should operate normally.
STEP 14. Check the wiring harness between blower switch connector C-41 (terminal 4) and front blower relay connector C-202 (terminal 4).
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 front blower relay ground line for open circuit.
Q: Is the wiring harness between blower switch connector C-41 (terminal 4) and front 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 front blower motor should operate normally.
STEP 15. Measure the resistance at front blower motor connector C-111 in order to the ground circuit to the blower motor.
1. Disconnect front blower motor connector C-111, 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 17.
NO: Go to Step 16.
STEP 16. Check the wiring harness between front blower motor connector C-111 (terminal 2) and ground.
- Check the front blower relay ground line for open circuit.
Q: Is the wiring harness between front blower motor connector C-111 (terminal 2) and ground in good condition?
YES : It can be assumed that this malfunction is intermittent.
NO : Repair the wiring harness. The front blower motor should operate normally.
STEP 17. Check the front 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 : It can be assumed that this malfunction is intermittent.
NO : Replace the front blower relay. The front blower motor should operate normally.