AIR CONDITIONING SYSTEM Blower Motor Circuit

DESCRIPTION

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

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

WIRING DIAGRAM

B0019WHE02
*a from Battery
*b Blower with Fan Motor Sub-assembly
*c Air Conditioning Amplifier Assembly

CAUTION / NOTICE / HINT

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE


  1. PERFORM ACTIVE TEST USING GTS (BLOWER MOTOR)


    1. Select the Active Test, use the GTS to generate a control command, and then check that the blower with fan motor sub-assembly operates Click here.

      Air Conditioner
      Tester Display Test Part Control Range Diagnostic Note
      Blower Motor Blower with fan motor sub-assembly Min.: 0, Max.: 31 -
      OK
      Blower with fan motor sub-assembly is operated normally using GTS.

    OK

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

    NG

  2. CHECK HARNESS AND CONNECTOR (BLOWER WITH FAN MOTOR SUB-ASSEMBLY - BATTERY AND BODY GROUND)


    1. B00183UE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Blower with Fan Motor Sub-assembly)

      Disconnect the blower with fan motor sub-assembly 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

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

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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (BLOWER WITH FAN MOTOR SUB-ASSEMBLY - AIR CONDITIONING AMPLIFIER ASSEMBLY)


    1. Disconnect the A29 blower with fan motor sub-assembly connector.

    2. Disconnect the E36 air conditioning amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      A29-2 (SI) - E36-3 (BLW) Always Below 1 Ω
      A29-2 (SI) or E36-3 (BLW) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY


    1. B0019XME02
      Text in Illustration
      *a

      Component with harness connected

      (Blower with Fan Motor Sub-assembly)

      Using an oscilloscope, check the waveform

      Measurement Condition
      Item Content
      Terminal No. (Symbol) A29-2 (SI) - Body ground
      Tool Setting 1 V/DIV., 500 μs/DIV.
      Condition

      • Engine switch on (IG)

      • Blower switch LO
      OK
      Waveform is as shown in the illustration.

      Tech Tips

      Waveform varies with the blower level.


    OK

    REPLACE BLOWER WITH FAN MOTOR SUB-ASSEMBLY Click here

    NG

  5. CHECK BLOWER WITH FAN MOTOR SUB-ASSEMBLY


    1. Replace the blower with fan motor sub-assembly with a new or known good one Click here.

    2. Check that the air conditioning system is operated normally.

      OK
      Air conditioning system is operated normally.

    OK

    END (BLOWER WITH FAN MOTOR SUB-ASSEMBLY WAS DEFECTIVE)

    NG

    REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Click here