Automatic Air Conditioning System

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM (for Automatic Air Conditioning System): B1413/13: Evaporator Temperature Sensor Circuit
B1413/13 - 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 A/C 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 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) Check the value(s) by referring to the table below.

Air Conditioner





OK:

The display is as specified in the "Normal Condition" column.

Result:





C -- REPLACE AIR CONDITIONING AMPLIFIER Removal

B -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Air Conditioning System (For Automatic Air Conditioning System)
A -- Continue to next step.

2. INSPECT EVAPORATOR TEMPERATURE SENSOR

(a) Remove the evaporator temperature sensor.

(b) Disconnect the connector from the evaporator temperature sensor.





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

Standard Resistance:





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).

Text in Illustration





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

3. INSPECT AIR CONDITIONING HARNESS

(a) Remove the air conditioning harness.





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

Standard Resistance:





Text in Illustration





NG -- REPLACE AIR CONDITIONING HARNESS Disassembly

OK -- REPLACE AIR CONDITIONING AMPLIFIER Removal