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 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 ACTIVE TEST USING INTELLIGENT TESTER OR TECHSTREAM (BLOWER MOTOR)
(a) Select the Active Test, using the intelligent tester or Techstream to generate a control command, and then check that the blower motor operates.
(1) Intelligent tester

AIR CONDITIONER





(2) Techstream

Air Conditioner





Result





C -- CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BLOWER MOTOR)
B -- INSPECT FUSE (HTR)
A -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
2. INSPECT FUSE (HTR)
(a) Remove the HTR H-fuse from the engine room No. 1 relay block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE FUSE
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - BODY GROUND)





(a) Disconnect the z20 blower motor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






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





(a) Disconnect the z20 blower motor connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5. CHECK BLOWER MOTOR (SI VOLTAGE)





(a) Disconnect the L76 air conditioning amplifier connector.
(b) Reconnect the z20 blower motor connector.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - AIR CONDITIONING AMPLIFIER)
OK -- Continue to next step.
6. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BLOWER MOTOR)





(a) Disconnect the L76 air conditioning amplifier connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
7. CHECK AIR CONDITIONING AMPLIFIER (BLW SIGNAL)





(a) Remove the air conditioning amplifier with its connectors still connected Removal.
(b) Using an oscilloscope, check the waveform.

Measurement condition





OK:
Waveform is as shown in the illustration.
HINT: Waveform varies with the blower level.

NG -- REPLACE AIR CONDITIONING AMPLIFIER
OK -- REPLACE BLOWER MOTOR
8. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - AIR CONDITIONING AMPLIFIER)





(a) Disconnect the L76 air conditioning amplifier connector.
(b) Disconnect the z20 blower motor connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE BLOWER MOTOR