B1431

AIR CONDITIONING SYSTEM: B1431/31: Air Mix Damper Position Sensor Circuit (Passenger Side)

DTC B1431/31 - Air Mix Damper Position Sensor Circuit (Passenger Side)

DESCRIPTION





This sensor detects the position of the air mix control servo motor (air mix damper) and sends the appropriate signals to the A/C amplifier. The position sensor is built in the air mix control servo motor. The position sensor resistance changes as the air mix control arm moves.
It outputs voltage (5 V) that is input to terminal 1 (VZ) and terminal 3 (PT) via the variable resistor, and then to the A/C amplifier.
The A/C amplifier reads the arm position with the input voltage from the position sensor.






WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING INTELLIGENT TESTER
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch ON and push the intelligent tester main switch on.
(c) Select the item below in the DATA LIST, and read the display on the intelligent tester.

DATA LIST / AIR CONDITIONER:





OK:
The display is as specified in the normal condition.
Result:






C -- REPLACE AIR CONDITIONING AMPLIFIER
B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- Continue to next step.
2. INSPECT AIR CONDITIONING AMPLIFIER





(a) Remove the A/C amplifier with the connectors still connected.
(b) Change the set temperature to activate the air mix servo motor.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:





HINT: As the set temperature increases, the voltage decreases gradually without interruption.

Result:






C -- REPLACE AIR CONDITIONING AMPLIFIER
B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- Continue to next step.
3. INSPECT AIR MIX CONTROL SERVO MOTOR





(a) Remove the air mix control servo motor.
(b) Disconnect the connector from the air mix control servo motor.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(d) Measure the resistance according to the value(s) in the table below.
Standard resistance:










(e) As the air mix control servo motor moves from cool side to hot side, the resistance decreases gradually without interruption.
HINT: For details regarding operation of the servo motor B1441.

NG -- REPLACE AIR MIX CONTROL SERVO MOTOR
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (AIR MIX CONTROL SERVO MOTOR - A/C AMPLIFIER)





(a) Disconnect the connector from the A/C amplifier.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE AIR CONDITIONING AMPLIFIER