Room Temperature Sensor Circuit - Air Conditioning System

AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1411/11: Room Temperature Sensor Circuit
B1411/11 - Room Temperature Sensor Circuit

DESCRIPTION

The room temperature sensor for the front seat is installed in the instrument panel to detect the room temperature and control the heater and air conditioner "AUTO" mode. The resistance of the room temperature sensor changes in accordance with the room temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier applies voltage (5 V) to the room temperature sensor and reads voltage changes as the resistance of the room temperature sensor changes. This sensor also sends the appropriate signals to the air conditioning amplifier.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM (ROOM TEMPERATURE SENSOR)

(a) Use the Data List to check if the room temperature sensor is functioning properly.

Air Conditioner





Result





B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

C -- REPLACE AIR CONDITIONING AMPLIFIER Removal
A -- Continue to next step.

2. INSPECT ROOM TEMPERATURE SENSOR





(a) Remove the room temperature sensor Removal.

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

Standard resistance:





NOTICE:
* Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
* When measuring, the sensor temperature must be the same as the ambient temperature.

HINT
As the temperature increases, the resistance decreases (see the graph).

NG -- REPLACE ROOM TEMPERATURE SENSOR Removal
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (ROOM TEMPERATURE - AIR CONDITIONING AMPLIFIER)





(a) Disconnect the L37 room temperature sensor connector.

(b) Disconnect the L77 air conditioning amplifier connector.

(c) 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 Removal