Blower Motor Circuit

TROUBLE DIAGNOSIS


Blower Motor Circuit


SYMPTOM:
- Blower motor operation is malfunctioning.

INSPECTION FLOW
1.CONFIRM SYMPTOM BY PERFORMING OPERATIONAL CHECK - FRONT BLOWER
1. Turn blower control dial clockwise one detent. Blower should operate on low speed.
2. Continue checking blower speed until all speeds are checked.
3. Leave blower on HI speed.
Can the symptom be duplicated?
YES - GO TO 3.
NO - GO TO 2.
2.PERFORM COMPLETE OPERATIONAL CHECK
Perform a complete operational check and check for any symptoms. Operational Check.
Can a symptom be duplicated?
YES - How To Perform Trouble Diagnosis For Quick And Accurate Repair.
NO - System OK.
3.CHECK FOR SERVICE BULLETINS
Check for any service bulletins.
- GO TO 4.
4.CHECK BLOWER MOTOR CIRCUIT
Perform diagnostic procedure for the blower motor circuit. Refer to "DIAGNOSTIC PROCEDURE".
OK or NG
OK - If the symptom still exists, perform a complete operational check and check for other symptoms. Operational Check. and check for other symptoms. How To Perform Trouble Diagnosis For Quick And Accurate Repair. If no other symptom exists replace front air control. Service and Repair.
NG - Repair as necessary.

SYSTEM DESCRIPTION

Component Parts

Fan speed control system components are:
- Front air control
- LAN system (PBR built-in mode door motor, air mix door motor and intake door motor)
- Blower motor
- Fan control amplifier

System Operation






COMPONENT DESCRIPTION

Fan Control Amplifier





The fan control amplifier (1) is located on the cooling unit. The fan control amp. receives a gate voltage from the front air control to smoothly maintain the blower fan motor voltage in the 5 to the 12V range (approx.).

DIAGNOSTIC PROCEDURE





SYMPTOM: Blower motor is malfunctioning.
1.CHECK POWER SUPPLY FOR FAN CONTROL AMP.





1. Disconnect fan control amp. connector.
2. Turn ignition switch ON.
3. Check voltage between fan control amp. harness connector
M52 terminal 3 and ground.





OK or NG
OK - GO TO 2.
NG - GO TO 7.
2.CHECK FAN FEEDBACK CIRCUIT





1. Disconnect front air control connector.
2. Check voltage between front air control harness connector M33 terminal 36 and ground.





OK or NG
OK - GO TO 3.
NG - Check for open circuit in wiring harness. Repair or replace as necessary.
3.CHECK BODY GROUND CIRCUIT FOR FAN CONTROL AMP.





1. Turn ignition switch OFF.
2. Check continuity between fan control amp. harness connector
M52 terminal 1 and ground.





OK or NG
OK - Reconnect fan control amp. harness connector and GO
TO 4.
NG - Repair harness or connector.
4.CHECK VOLTAGE FOR FAN CONTROL AMP.





1. Turn ignition switch ON.
2. Turn blower control dial to any position except OFF or AUTO.
3. Check voltage between fan control amp. harness connector
M52 terminal 2 and ground.





OK or NG
OK - 1. Replace fan control amp. Service and Repair.
2. Confirm that blower motor operation is normal.
NG - GO TO 5.
5.CHECK FAN CONTROL AMP. CIRCUIT BETWEEN FAN CONTROL AMP. AND FRONT AIR CONTROL





1. Turn ignition switch OFF.
2. Disconnect front air control and fan control amp. harness connectors.
3. Check continuity between fan control amp. harness connector
M52 (A) terminal 2 and front air control harness connector M33
(B) terminal 37.





If OK, check harness for short.
OK or NG
OK - GO TO 6.
NG - Repair harness or connector.
6.CHECK POWER SUPPLY FOR FRONT AIR CONTROL





1. Turn ignition switch ON.
2. Check voltage between front air control harness connector M33 terminal 1 and ground.





OK or NG
OK - 1. Replace front air control. Service and Repair.
2. Confirm that blower motor operation is normal.
NG -
- Check for open circuit in wiring harness.
Repair or replace as necessary.
- If OK, replace fuse and check wiring harness for short circuit.
Repair or replace an necessary.
7.CHECK POWER SUPPLY FOR BLOWER MOTOR
1. Turn ignition OFF.
2. Disconnect blower motor harness connector.
3. Turn ignition switch ON.





4. Check voltage between blower motor harness connector M62 terminal 1 and ground.





OK or NG
OK - GO TO 8.
NG - Check power supply circuit and 15A fuses [Nos. 10 and 11, located in the fuse block (J/B)].
- Check blower motor relay. Electrical Diagrams.
Repair or replace as necessary.
- If OK, check for open circuit in wiring harness.
Repair or replace as necessary.
- If OK, replace fuse and check wiring harness for short circuit.
Repair or replace as necessary.
8.CHECK CIRCUIT CONTINUITY BETWEEN BLOWER MOTOR AND FAN CONTROL AMP.





1. Turn ignition switch OFF.
2. Disconnect front air control connector.
3. Check continuity between blower motor harness connector M62
3. terminal 2 and fan control amp. harness connector M52 terminal 3.






OK or NG
OK - Check blower motor. Blower Motor Circuit.
1. If NG, replace blower motor. Service and Repair.
2. Confirm that blower motor operation is normal.
NG - Repair harness or connector.

COMPONENT INSPECTION

Blower Motor





Confirm smooth rotation of the blower motor (1).
- Ensure that there are no foreign particles inside the intake unit.