Blower Motor Circuit

AIR CONDITIONING: AIR CONDITIONING SYSTEM: Blower Motor Circuit

Blower Motor Circuit

DESCRIPTION

The blower motor is operated by signals from the A/C amplifier. Blower motor speed signals are transmitted by changes in the Duty Ratio.





Duty Ratio
- The duty ratio is the ratio of the blower motor ON time (A) to the total of the blower motor ON and OFF time (A + B). The blower motor controller controls the blower motor speed.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTUATOR CHECK
(a) Operate the A/C control panel to enter the actuator check mode Actuator Check.
(b) Press the blower switch and change it to the step operation.
(c) Check the air flow temperature by hand.






OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
NG -- Continue to next step.
2. INSPECT FUSE (HEATER NO. 2)




(a) Remove the HEATER No. 2 fuse from the engine room R/B.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE FUSE (HTR NO. 2)
OK -- Continue to next step.
3. INSPECT BLOWER WITH FAN MOTOR SUB-ASSEMBLY




(a) Remove the blower with fan motor sub-assembly.
(b) Connect the battery positive (+) lead to terminal 2 and the battery negative (-) lead to terminal 1.
OK:
Blower motor operates smoothly.
NG -- REPLACE BLOWER WITH FAN MOTOR SUB-ASSEMBLY
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (HEATER BLOWER MOTOR RELAY - BLOWER MOTOR CONTROL)
(a) Check for open and short circuit in the harness and the connector between the blower motor relay and the blower motor control Electronic Circuit Inspection Procedure.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR CONTROL - BODY GROUND)
(a) Check for open and short circuit in the harness and the connector between the blower motor control and body ground Electronic Circuit Inspection Procedure.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
6. INSPECT AIR CONDITIONING AMPLIFIER (BLC)




(a) Remove the A/C amplifier with the connectors still connected.
(b) Turn the ignition switch ON.
(c) Set the blower speed to LO.




(d) Measure the waveform between terminal A15-6 (BLC) of the A/C amplifier and body ground.
OK:
Waveform appears as shown in the illustration.
HINT: Waveform varies with the blower level.

NG -- REPLACE AIR CONDITIONING AMPLIFIER
OK -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR CONTROL - A/C AMPLIFIER)
(a) Check for open and short circuit in the harness and the connector between the blower motor control and the A/C amplifier Electronic Circuit Inspection Procedure.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE BLOWER MOTOR CONTROL