B1413

AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1413: Evaporator Temperature Sensor Circuit
B1413 - Evaporator Temperature Sensor Circuit

DESCRIPTION

The evaporator temperature sensor (A/C thermistor) is installed on the evaporator in the air conditioning unit. It detects the temperature of the cooled air that has passed through the evaporator and its signal is used to control the air conditioning. It sends a signal to the air conditioning amplifier. The resistance of the evaporator temperature sensor (A/C thermistor) changes in accordance with the temperature of the cooled air that has passed through the evaporator. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier applies voltage (5 V) to the evaporator temperature sensor (A/C thermistor) and reads voltage changes as the resistance of the evaporator temperature sensor (A/C thermistor) changes. This sensor is used to prevent the evaporator from freezing.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM (EVAPORATOR FIN THERMISTOR)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the tester on.

(d) Select the following menus: Body Electrical / Air Conditioner / Data List / Evaporator Fin Thermistor

(e) According to the display on tester, read the "Data List".

Evaporator Fin Sensor:





OK:

The display is as specified in the normal condition column.

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 EVAPORATOR TEMPERATURE SENSOR

(a) Disconnect the G2 evaporator temperature sensor connector.





(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).

(c) Reconnect the evaporator temperature sensor connector.

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

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

(a) Disconnect the G2 evaporator temperature sensor connector.





(b) Disconnect the G7 air conditioning amplifier connector.

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

Standard resistance:





(d) Reconnect the air conditioning amplifier connector.

(e) Reconnect the evaporator temperature sensor connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER Removal