B1413

HEATING / AIR CONDITIONING: AIR CONDITIONING SYSTEM: B1413/13: Evaporator Temperature Sensor Circuit
B1413/13 - Evaporator Temperature Sensor Circuit

DESCRIPTION

The evaporator temperature sensor (No. 1 cooler thermistor) is installed on the evaporator in the air conditioner unit to detect the temperature of the air that has passed through the evaporator. Its signal is used for air conditioning control. It sends signals to the air conditioning amplifier assembly. The resistance of the evaporator temperature sensor (No. 1 cooler 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 air conditioning amplifier assembly applies voltage (5 V) to the evaporator temperature sensor (No. 1 cooler thermistor) and reads voltage changes as the resistance of the evaporator temperature sensor (No. 1 cooler 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 power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / 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:





B -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

C -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal
A -- Continue to next step.

2. INSPECT EVAPORATOR TEMPERATURE SENSOR (NO. 1 COOLER THERMISTOR)

(a) Remove the evaporator temperature sensor (No. 1 cooler thermistor) Removal.

(b) Disconnect the a1 evaporator temperature sensor (No. 1 cooler thermistor) 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).

Text in Illustration





NG -- REPLACE EVAPORATOR TEMPERATURE SENSOR (NO. 1 COOLER THERMISTOR) Removal
OK -- Continue to next step.

3. INSPECT AIR CONDITIONING HARNESS ASSEMBLY

(a) Remove the air conditioning harness assembly Disassembly.

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

Standard Resistance:





NG -- REPLACE AIR CONDITIONING HARNESS ASSEMBLY Disassembly

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal