B1413

HEATING / 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 passed through the evaporator and its signal sent to the A/C amplifier is used to control the air conditioning. The resistance of the evaporator temperature sensor (A/C thermistor) changes in accordance with the temperature of the cooled air passed through the evaporator. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The A/C 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

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Body / Air Conditioner / Data List.

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

Air Conditioner





OK:

The display is as specified in the Normal Condition column.

Result:





B -- PROCEED TO NEXT SUSPECTED AREA 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 connector from the evaporator temperature sensor.





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

Standard Resistance:





NOTICE:
* Hold the sensor only by its connector. Touching the 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).

Text in Illustration





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

3. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - EVAPORATOR TEMPERATURE SENSOR)

(a) Disconnect the connector from the A/C amplifier.

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

Standard Resistance:





*1: for 2AZ-FE

*2: for 2ZR-FE

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER Removal