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 TECHSTREAM (BLOWER MOTOR)
(a) Select the Active Test, using the Techstream to generate a control command, and then check that the blower motor operates.
Air Conditioner
Result
B -- CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BLOWER MOTOR)
C -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures
A -- Continue to next step.
2. INSPECT FUSE (HTR)
(a) Remove the HTR H-fuse from the engine room No. 1 relay block.
(b) Measure the resistance of the fuse.
Standard resistance:
NG -- REPLACE FUSE
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - BODY GROUND)
(a) Disconnect the A40*1 or v1*2 blower motor connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
w/o Air Suspension
w/ Air Suspension
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - BATTERY)
(a) Disconnect the A40*1 or v1*2 blower motor connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:
w/o Air Suspension
w/ Air Suspension
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) Measure the voltage according to the value(s) in the table below.
Standard voltage:
w/o Air Suspension
w/ Air Suspension
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) Turn the engine switch on (IG).
(c) Turn the blower switch ON (Lo).
(d) Using an oscilloscope, check the waveform.
Waveform (Reference):
OK:
Waveform is as shown in the illustration.
HINT
Waveform varies with the blower level.
NG -- REPLACE AIR CONDITIONING AMPLIFIER Removal
OK -- REPLACE BLOWER MOTOR Removal
8. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - AIR CONDITIONING AMPLIFIER)
(a) Disconnect the L76 air conditioning amplifier connector.
(b) Disconnect the A40*1 or v1*2 blower motor connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:
w/o Air Suspension
w/ Air Suspension
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE BLOWER MOTOR Removal