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







PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Select the item below in the Active Test and then check that the relay operates.

Active Test / Air Conditioner:





Result:





C -- CHECK WIRE HARNESS (A/C AMPLIFIER - BODY GROUND)

B -- INSPECT FUSE

A -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

2. INSPECT FUSE

(a) Remove the HEATER fuse and ALT fuse from the engine room No. 1 junction block.

(b) Measure the resistance of the fuse.

Standard resistance:





NG -- REPLACE FUSE
OK -- Continue to next step.

3. CHECK WIRE HARNESS (BLOWER MOTOR - BODY GROUND)





(a) Disconnect the blower motor 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.

4. CHECK WIRE HARNESS (BLOWER MOTOR - BATTERY)





(a) Disconnect the blower motor 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.

5. INSPECT BLOWER MOTOR





(a) Disconnect the A/C amplifier connector.

(b) Connect the blower motor connector.

(c) Measure the voltage of the connector.

Standard voltage:





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

6. CHECK WIRE HARNESS (A/C AMPLIFIER - BODY GROUND)





(a) Disconnect the A/C amplifier 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.

7. INSPECT AIR CONDITIONING AMPLIFIER

(a) Remove the A/C amplifier with its connectors still connected.





(b) Turn the engine switch on (IG).

(c) Turn the blower switch ON (Lo).

(d) Measure the waveform between terminal K52-11 (BLW) of the A/C amplifier and body ground.

OK:

Waveform is as shown in the illustration.

HINT
Waveform varies with the blower level.





NG -- REPLACE AIR CONDITIONING AMPLIFIER

OK -- REPLACE BLOWER MOTOR