AIR CONDITIONING SYSTEM Blower Motor Circuit

DESCRIPTION

A01EQ1RE01

The blower motor sub-assembly (with fan) is operated by signals from the air conditioning amplifier assembly. The 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 blower motor sub-assembly (with fan) OPEN time (T1) to the total of the blower motor sub-assembly (with fan) OPEN and LO time (T2).

The air conditioning amplifier assembly controls the blower motor sub-assembly (with fan) speed.

WIRING DIAGRAM

A01EMYSE06

INSPECTION PROCEDURE

PROCEDURE


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


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

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

    B

    CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - BODY GROUND) Click here

    C

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

    A

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

  2. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - BODY GROUND)

    A01ENU8E23

    1. Disconnect the A29 motor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A29-1 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (BLOWER MOTOR - BATTERY)

    A01ENU8E24

    1. Disconnect the A29 motor connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A29-3 (+B) - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK BLOWER MOTOR SUB-ASSEMBLY (SI VOLTAGE)

    A01EQG6E02

    1. Disconnect the E36 amplifier connector.

    2. Reconnect the A29 motor connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A29-2 (SI) - Body ground Engine switch on (IG) 4.5 to 5.5 V

    NG

    REPLACE BLOWER MOTOR SUB-ASSEMBLY Click here

    OK

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

    A01ERP4E01

    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
      E36-3 (BLW) - E36-1 (GND)

      Engine switch on (IG)

      Blower switch off

      		 4.5 to 5.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here

  6. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BLOWER MOTOR)

    A01ERP4E01

    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
      E36-3 (BLW) - E36-1 (GND)

      Engine switch on (IG)

      Blower switch off

      		 4.5 to 5.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  7. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY (BLW SIGNAL)


    1. A01EN51E04

      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) E36-3 (BLW) - 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

    REPLACE BLOWER MOTOR SUB-ASSEMBLY Click here