Blower Motor Circuit

AIR CONDITIONING: AIR CONDITIONING SYSTEM: Blower Motor Circuit

Blower Motor Circuit

DESCRIPTION





The blower motor is operated by signals from the air conditioning amplifier. 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.
The blower motor controller controls the blower motor speed.
The blower motor controller reads the signal from the air conditioning amplifier and controls rotation and speed.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST BY TECHSTREAM
(a) Connect Techstream to DLC3.
(b) Turn the power switch ON (IG) and turn Techstream ON.
(c) Select the item below in the Active Test and then check that the relay operates.

Air conditioning amplifier





Result





C -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
B -- CHECK WIRE HARNESS (BLOWER MOTOR CONTROLLER - AIR CONDITIONING AMPLIFIER)
A -- Continue to next step.

2. INSPECT BLOWER W/ FAN MOTOR SUB-ASSEMBLY




(a) Remove the cooling unit motor w/ fan.
(b) Connect the battery's positive (+) lead to terminal 1 of blower motor and negative (-) lead to terminal 2.
OK:
Blower motor operates smoothly.
NG -- REPLACE BLOWER W/ FAN MOTOR SUB-ASSEMBLY
OK -- Continue to next step.

3. CHECK WIRE HARNESS (BLOWER MOTOR CONTROLLER - BATTERY)




(a) Disconnect the B3 controller connector.
(b) Measure the voltage of the wire harness side connector.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.

4. CHECK WIRE HARNESS (BLOWER MOTOR CONTROLLER - BODY GROUND)




(a) Disconnect the B3 controller connector.
(b) Measure the resistance of the wire harness side connector.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.

5. CHECK WIRE HARNESS (BLOWER MOTOR - BLOWER MOTOR CONTROLLER)




(a) Disconnect the B2 motor connector.
(b) Disconnect the B4 controller connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.

6. CHECK WIRE HARNESS (BLOWER MOTOR CONTROLLER - AIR CONDITIONING AMPLIFIER)




(a) Disconnect the B3 controller connector.
(b) Disconnect the A8 amplifier connector.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.

7. CHECK BLOWER MOTOR CONTROLLER (BLW VOLTAGE)




(a) Disconnect the A8 amplifier connector.
(b) Measure the voltage of the wire harness side connector.
Standard voltage:






NG -- REPLACE BLOWER MOTOR CONTROLLER
OK -- Continue to next step.

8. CHECK AIR CONDITIONING AMPLIFIER (BLW - BODY GROUND)




(a) Remove the air conditioning amplifier with its connectors still connected.
(b) Turn the power switch ON (IG).
(c) Turn the blower switch ON (Lo).




(d) Using an oscilloscope, measure the waveform of the amplifier.
OK:
Waveform is as shown in the illustration.





HINT: Waveform varies depending on the blower switch setting.

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