AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System) Rear Blower Motor Circuit

DESCRIPTION

A0156D2E02

The rear blower motor (w/ rear heater) is operated by signals from the air conditioning amplifier assembly. The rear blower motor speed signals are transmitted by changes in the duty ratio.

Duty Ratio:

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

The rear blower motor controller controls the rear blower motor speed.

WIRING DIAGRAM

A015ABKE03

INSPECTION PROCEDURE

PROCEDURE


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


    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 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 (WIRING AIR CONDITIONING HARNESS - BODY GROUND) Click here

    C

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

    A

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

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

    A015AG1E01

    1. Disconnect the wiring air conditioning 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 (WIRING AIR CONDITIONING HARNESS - BATTERY)

    A015AG1E02

    1. Disconnect the wiring air conditioning 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 WIRING AIR CONDITIONING HARNESS SUB-ASSEMBLY (SI VOLTAGE)

    A015ACWE01

    1. Disconnect the E36 amplifier connector.

    2. Reconnect the wiring air conditioning 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 WIRING AIR CONDITIONING HARNESS SUB-ASSEMBLY (OPERATION) Click here

    OK

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

    A0155VCE03

    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. A015BRXE02

      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 WIRING AIR CONDITIONING HARNESS SUB-ASSEMBLY (OPERATION)


    1. Replace the wiring air conditioning 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 Click here

    OK

    REPLACE WIRING AIR CONDITIONING HARNESS SUB-ASSEMBLY

  8. INSPECT REAR BLOWER MOTOR


    1. A0156K6E01

      Disconnect the z32 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 Click here

    OK

    REPLACE REAR BLOWER MOTOR CONTROLLER Click here