AIR CONDITIONING SYSTEM Blower Motor Circuit

DESCRIPTION

A000V3HE06

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

A000W22E11
*a from Battery
*b Blower Motor
*c Air Conditioning Amplifier

PROCEDURE


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


    1. Select the Active Test, using 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 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

    A

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

    C

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

    B

  2. INSPECT FUSE (HTR)


    1. Remove the HTR H-fuse from the engine room No. 1 relay block.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      HTR H-fuse Always Below 1 Ω

    NG

    REPLACE FUSE

    OK

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

    A00103QE02
    *1 Front view of wire harness connector: (to Blower Motor)

    1. Disconnect the z20 blower motor connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      z20-1 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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

    A000XC8E02
    *1 Front view of wire harness connector: (to Blower Motor)

    1. Disconnect the z20 blower motor connector.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      z20-3 (+B) - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK BLOWER MOTOR (SI VOLTAGE)

    A000X6TE02
    *1 Component with harness connected: (Blower Motor)

    1. Disconnect the L76 air conditioning amplifier connector.

    2. Reconnect the z20 blower motor connector.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      z20-2 (SI) - Body ground Power switch ON (IG) 4.5 to 5.5 V

    NG

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

    OK

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

    A000VU9E03
    *1 Rear view of wire harness connector: (to Air Conditioning Amplifier)

    1. Disconnect the L76 air conditioning amplifier connector.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      L76-3 (BLW) - L76-1 (GND)

      Power 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 (BLW SIGNAL)


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

      A001000E01
      *a Component with harness connected: (Air Conditioning Amplifier)
      *b 1 V/DIV.
      *c 500 μsec./DIV.

    2. Using an oscilloscope, check the waveform.

      Measurement condition
      Item Content
      Tester Connection L76-3 (BLW) - L76-1 (GND)
      Tool Setting 1 V/DIV., 500 μsec./DIV.
      Condition

      Power switch ON (IG)

      Blower switch: OFF → ON
      OK
      Waveform is as shown in the illustration.

      Tech Tips

      Waveform varies with the blower level.


    OK

    REPLACE BLOWER MOTOR Click here

    NG

    REPLACE AIR CONDITIONING AMPLIFIER Click here

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

    A000W2PE05
    *1 Front view of wire harness connector: (to Blower Motor)
    *2 Rear view of wire harness connector: (to Air Conditioning Amplifier)

    1. Disconnect the L76 air conditioning amplifier connector.

    2. Disconnect the z20 blower motor connector.

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

      Standard resistance
      Tester Connection Condition Specified Condition
      z20-2 (SI) - L76-3 (BLW) Always Below 1 Ω
      z20-2 (SI) - Body ground Always 10 kΩ or higher
      L76-3 (BLW) - Body ground

    OK

    REPLACE BLOWER MOTOR Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR