Blower Motor Circuit

HEATING / 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 blower motor OFF time (B) 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 ACTIVE TEST USING TECHSTREAM (BLOWER MOTOR)
(a) Connect the Techstream to DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Body Electrical / Air Conditioner / Active Test/ Blower Motor
(e) According to the display on the Techstream, check blower motor operation while performing the Active Test.

Air Conditioner





Result





C -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
B -- CHECK BLOWER MOTOR (S1 VOLTAGE)
A -- Continue to next step.
2. INSPECT FUSE (HTR)





(a) Remove the HTR fuse from the engine room relay block.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:





(c) Reinstall the HTR fuse.
NG -- REPLACE FUSE
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - BATTERY AND BODY GROUND)





(a) Disconnect the H41 blower motor connector.
(b) Measure the resistance and voltage according to the value(s) in the table below.
Standard Resistance:






Standard Voltage:





(c) Reconnect the blower motor connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BLOWER MOTOR)





(a) Disconnect the H24 air conditioning amplifier connector.
(b) Disconnect the H41 blower motor connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:





(d) Reconnect the blower motor connector.
(e) Reconnect the air conditioning amplifier connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5. CHECK BLOWER MOTOR (S1 VOLTAGE)





(a) Disconnect the H24 air conditioning amplifier connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard Voltage:





(c) Reconnect the air conditioning amplifier connector.
NG -- REPLACE BLOWER MOTOR
OK -- Continue to next step.
6. INSPECT AIR CONDITIONING AMPLIFIER (BLW VOLTAGE)





(a) Remove the air conditioning amplifier with its connectors still connected Removal.
(b) Turn the ignition switch to ON.
(c) Turn the blower switch to LO.
(d) Using an oscilloscope, check the waveform.

Blower Motor Control Signal





HINT: Waveform varies with the blower level.
(e) Reinstall the air conditioning amplifier.
NG -- REPLACE AIR CONDITIONING AMPLIFIER
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE