Rear Air Mix Damper Position Sensor Circuit - Air Conditioning System (for Automatic Air Conditioning System)

AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System): B1437/37: Rear Air Mix Damper Position Sensor Circuit

DTC B1437/37 - Rear Air Mix Damper Position Sensor Circuit

DESCRIPTION





This sensor detects the position of the rear air mix control servo motor (water valve servo motor) and sends the appropriate signals to the A/C amplifier. The position sensor is built in the rear air mix control servo motor (water valve servo motor).
The position sensor's resistance changes as the rear air mix control servo motor valve moves.
It outputs voltage (5 V) that is input to terminal 2 and terminal 3 via the variable resistor, and then to the A/C amplifier.
The A/C amplifier determines the valve position based on the input voltage from the position sensor.






WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch to the ON position and turn Techstream on.
(c) Select the items below in the Data List, and read the display on Techstream.

Data List / Air Conditioner:





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






C -- REPLACE A/C AMPLIFIER
B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- Continue to next step.
2. INSPECT REAR AIR MIX CONTROL SERVO MOTOR (WATER VALVE SERVO MOTOR)





(a) Remove the rear air mix control servo motor (water valve servo motor).
(b) Disconnect the connector from the rear air mix control servo motor (water valve 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.
HINT:
- In order to turn the motor to the "MAX. COOL" position, connect the positive (+) lead to terminal 5, and the negative (-) lead to terminal 4.
- In order to turn the motor to the "MAX. HOT" position, connect the positive (+) lead to terminal 4, and the negative (-) lead to terminal 5.

Standard resistance:










(e) As the rear air mix control servo motor (water valve servo motor) moves from the cool side to the hot side, the resistance decreases gradually without interruption.
NG -- REPLACE REAR AIR MIX CONTROL SERVO MOTOR (WATER VALVE SERVO MOTOR)
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (REAR 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 A/C AMPLIFIER