B1411

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

DESCRIPTION

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

The air conditioning amplifier applies a voltage (5 V) to the room temperature sensor and reads voltage changes as changes in the resistance of the room temperature sensor.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Select the item below in the Data List, and read the display on the Techstream.

Data List / Air Conditioner

OK:

The display is as specified in the normal condition column.

Result:

C -- REPLACE A/C AMPLIFIER Removal

B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures
A -- Continue to next step.

2. INSPECT ROOM TEMPERATURE SENSOR

(a) Remove the room temperature sensor.

(b) Disconnect the room temperature sensor connector.

NOTICE:
* Hold the sensor only by its connector. Touching the sensor may change the resistance value.
* 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 SENSOR - A/C AMPLIFIER)

(a) Disconnect the A/C amplifier connector.

(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 Removal