Blower Motor Circuit

AIR CONDITIONING SYSTEM: Blower Motor Circuit

Blower Motor Circuit

DESCRIPTION





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

Duty Ratio:
- The duty ratio is the ratio of the period of continuity in one cycle. For example, A is the period of continuity in one cycle, and B is the period of non-continuity.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE OF TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON and push the Techstream main switch on.
(c) Select the item below in the DATA LIST, and read the display on the Techstream.

Air Conditioner





OK:
The display is as specified in the normal condition.
NG -- PERFORM ACTIVE TEST BY TECHSTREAM
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
2. PERFORM ACTIVE TEST BY TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch ON and push the Techstream main switch on.
(c) Select the item below in the ACTIVE TEST and then check that the blower motor operates.

Air Conditioner





OK:
Blower motor operates and blower level changes.
NG -- PERFORM ACTUATOR CHECK
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
3. PERFORM ACTUATOR CHECK
(a) Set the actuator check mode. Actuator Check

(b) Press the blower switch to change to the step operation.
(c) Check for air flow level by hand.






OK:
Blower level changes in accordance with each display code.
NG -- CHECK HARNESS AND CONNECTOR (BLOWER MOTOR CONTROLLER - A/C AMPLIFIER ASSEMBLY)
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
4. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR CONTROLLER - A/C AMPLIFIER ASSEMBLY)





(a) Disconnect the connector from the A/C amplifier assembly and blower motor controller.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR CONTROLLER - BODY GROUND)





(a) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
6. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR CONTROLLER - BLOWER MOTOR)





(a) Disconnect the connector from the blower motor.
(b) Measure the voltage according to the value(s) in the table below.
Voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR CONTROLLER - BLOWER MOTOR)





(a) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
8. INSPECT COOLING UNIT MOTOR SUB-ASSEMBLY W/FAN





(a) Remove the cooling unit motor sub-assembly w/ fan.
(b) Connect the negative (-) lead to terminal 1 of blower motor connector, and the positive (+) lead to terminal 2.
OK:
Blower motor operates smoothly.
NG -- REPLACE COOLING UNIT MOTOR SUB-ASSEMBLY W/FAN
OK -- Continue to next step.
9. INSPECT AIR CONDITIONING AMPLIFIER ASSEMBLY
(a) Reconnect the connector to the A/C amplifier assembly.





(b) Remove the A/C amplifier assembly with the connectors still connected.
(c) Turn the ignition switch ON.
(d) Blower speed control switch is at "LO" position.





(e) Measure the waveform between terminal BLW (A8-9) of the A/C amplifier assembly and body ground.
OK:
Waveform appears as shown in the illustration.
HINT: Waveform cycle varies with the blower level.

NG -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY
OK -- REPLACE BLOWER MOTOR CONTROLLER