AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System), Diagnostic DTC:B1446/46

DTC Code DTC Name
B1446/46 Air Mix Damper Control Servo Motor Circuit (Driver Side)

DESCRIPTION

The air mix control servo motor sends pulse signals to indicate the damper position to the air conditioning amplifier. The air conditioning amplifier activates the motor (normal or reverse) based on these signals to move the air mix damper (driver side) to the appropriate position. This adjusts the amount of air passing through the heater core after passing the evaporator and controls the temperature of the blown air.

Tech Tips

Confirm that there are no mechanical problems because this DTC can be set if either a damper link or damper is mechanically locked.

DTC No. DTC Detection Condition Trouble Area
B1446/46 Air mix damper position does not change even if air conditioning amplifier operates air mix damper control servo motor

  • Air mix control servo motor

  • Air conditioning harness

  • Air conditioning amplifier

WIRING DIAGRAM

A017DCOE08

INSPECTION PROCEDURE

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (AIR MIX SERVO TARG PULSE (D))


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch on (IG) and turn the intelligent tester main switch on.

    3. Select the item below in the Data List, and read the value displayed on the intelligent tester.

      Data List / Air Conditioner:
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Air Mix Pulse-D

      Driver side air mix control servo motor target pulse /

      Min.: 0, Max.: 255

      • LHD:

        MAX. COLD: 5 (pulse)

        MAX. HOT: 103 (pulse)


      • RHD:

        MAX. COLD: 105 (pulse)

        MAX. HOT: 7 (pulse)

      		 -
      OK
      The display is as specified in the normal condition column.
      Result
      Result Proceed to
      NG A
      OK (Checking from PROBLEM SYMPTOMS TABLE) B
      OK (Checking from DTC) C

    B

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

    C

    REPLACE AIR CONDITIONING AMPLIFIER Click here

    A

  2. REPLACE AIR MIX CONTROL SERVO MOTOR


    1. Replace the air mix control servo motor Click here.


    NEXT

  3. CHECK DTC OUTPUT


    1. Clear the DTC Click here.

    2. Check for DTC Click here.

      OK
      DTC B1446/46 is not output.

    NG

    REPAIR OR REPLACE AIR CONDITIONING HARNESS

    OK

    END (AIR MIX CONTROL SERVO MOTOR IS DEFECTIVE)