AIR CONDITIONING SYSTEM Rear Blower Motor Circuit

DESCRIPTION

A01EQ1RE02

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

A01ENDVE04

INSPECTION PROCEDURE

PROCEDURE


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


    1. Select the Active Test, use the intelligent tester to generate a control command, and then check that the rear blower motor operates.

      Air Conditioner
      Tester Display Test Part Control Range Diagnostic Note
      Rear Blower Motor Rear blower motor sub-assembly (with fan) Min.: 0, Max.: 31 -
      Result
      Result Proceed to
      Rear blower motor operates normally A
      Rear blower motor does not operate B
      Rear blower motor operates but does not change speed C

    B

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

    C

    CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - AIR CONDITIONING WIRING HARNESS) Click here

    A

    PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Click here

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

    A01ERZ3E01

    1. Disconnect the air conditioning wiring harness sub-assembly connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      4 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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

    A01ERZ3E02

    1. Disconnect the air conditioning wiring harness sub-assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      1 (+B) - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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

    A01ERHFE01

    1. Disconnect the E36 amplifier connector.

    2. Reconnect the air conditioning wiring harness sub-assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      8 (SI) - Body ground Engine switch on (IG) 4.5 to 5.5 V

    NG

    CHECK AIR CONDITIONING WIRING HARNESS SUB-ASSEMBLY (OPERATION) Click here

    OK

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

    A01ERP4E03

    1. Disconnect the E36 amplifier connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      E36-17 (BLWH) - E36-1 (GND)

      Engine switch on (IG)

      Blower switch off

      		 4.5 to 5.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY (BLWH SIGNAL)


    1. A01EN51E05

      Remove the air conditioning amplifier assembly with its connectors still connected Click here.

    2. Using an oscilloscope, check the waveform.

      Measurement Condition
      Item Content
      Terminal No. (Symbol) E36-17 (BLWH) - E36-1 (GND)
      Tool Setting 1 V/DIV., 500 μs/DIV.
      Condition

      Engine switch on (IG)

      Blower switch off → on
      OK
      Waveform is as shown in the illustration.

      Tech Tips

      Waveform varies with the blower level.


    NG

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

    OK

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


    1. 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) Click here

    OK

    REPLACE AIR CONDITIONING WIRING HARNESS SUB-ASSEMBLY

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


    1. A01EN47E01

      Disconnect the z31 motor connector.

    2. 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) Click here

    OK

    REPLACE BLOWER MOTOR CONTROLLER Click here