B1413

HEATING / AIR CONDITIONING: 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 conditioner unit to detect the cooled air temperature that has passed through the evaporator and control the air conditioning. It sends appropriate signals to the A/C amplifier. The resistance of the evaporator temperature sensor (A/C thermistor) changes in accordance with the cooled air temperature 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 for frost prevention.





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.

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 EVAPORATOR TEMPERATURE SENSOR

(a) Remove the evaporator temperature sensor.

(b) Disconnect the evaporator temperature sensor connector.





(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).

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

3. INSPECT AIR CONDITIONING HARNESS (A/C AMPLIFIER - EVAPORATOR TEMPERATURE SENSOR)

(a) Remove the air conditioning harness.

(1) Disconnect the A/C amplifier connector.





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





Standard Resistance:





NG -- REPLACE AIR CONDITIONING HARNESS Disassembly

OK -- REPLACE A/C AMPLIFIER Removal