Rear Blower Motor Circuit

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: Rear Blower Motor Circuit
- Rear Blower Motor Circuit

DESCRIPTION





The rear blower motor sub-assembly (with fan) is operated by signals from the air conditioning amplifier assembly. The rear blower motor sub-assembly (with fan) speed signals are transmitted by changes in the duty ratio.

Duty Ratio:

The duty ratio is the ratio of the rear blower motor sub-assembly (with fan) OPEN time (T1) to the total of the rear blower motor sub-assembly (with fan) OPEN and LO time (T2).

The blower motor controller controls the rear blower motor sub-assembly (with fan) speed.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM (REAR BLOWER MOTOR SUB-ASSEMBLY)

(a) Select the Active Test, use the Techstream to generate a control command, and then check that the rear blower motor operates.

Air Conditioner





Result





C -- CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - AIR CONDITIONING WIRING HARNESS)

B -- CHECK HARNESS AND CONNECTOR (AIR CONDITIONING WIRING HARNESS - BODY GROUND)

A -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

2. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING WIRING HARNESS - BODY GROUND)





(a) Disconnect the air conditioning wiring harness sub-assembly 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.

3. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING WIRING HARNESS - BATTERY)





(a) Disconnect the air conditioning wiring harness sub-assembly 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.

4. CHECK AIR CONDITIONING WIRING HARNESS SUB-ASSEMBLY (SI VOLTAGE)





(a) Disconnect the E36 amplifier connector.

(b) Reconnect the air conditioning wiring harness sub-assembly connector.

(c) Measure the voltage according to the value(s) in the table below.

Standard Voltage:





NG -- CHECK AIR CONDITIONING WIRING HARNESS SUB-ASSEMBLY (OPERATION)
OK -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - AIR CONDITIONING WIRING HARNESS)





(a) Disconnect the E36 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.

6. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY (BLWH SIGNAL)

(a) Remove the air conditioning amplifier assembly 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 ASSEMBLY Removal
OK -- Continue to next step.

7. CHECK AIR CONDITIONING WIRING HARNESS SUB-ASSEMBLY (OPERATION)

(a) Replace the air conditioning wiring harness sub-assembly with a normal one and check that the condition returns to normal.

OK:

Same problem does not occur.

NG -- INSPECT REAR BLOWER MOTOR SUB-ASSEMBLY (WITH FAN)

OK -- REPLACE AIR CONDITIONING WIRING HARNESS SUB-ASSEMBLY

8. INSPECT REAR BLOWER MOTOR SUB-ASSEMBLY (WITH FAN)

(a) Disconnect the z31 motor connector.





(b) Connect the positive (+) lead of the battery to terminal 2 and the negative (-) lead to terminal 1, then check that the rear blower motor operates smoothly.

OK:

The rear blower motor operates smoothly.

NG -- REPLACE REAR BLOWER MOTOR SUB-ASSEMBLY (WITH FAN) Removal

OK -- REPLACE BLOWER MOTOR CONTROLLER Removal