B1413

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

DESCRIPTION

The No. 1 cooler thermistor (evaporator temperature sensor) is installed on the evaporator in the air conditioning unit to detect the cooled air temperature that has passed through the evaporator and to control the air conditioning. It sends appropriate signals to the air conditioning amplifier assembly. The resistance of the No. 1 cooler thermistor (evaporator temperature sensor) 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 No. 1 cooler thermistor (evaporator temperature sensor) and reads voltage changes as the resistance of the No. 1 cooler thermistor (evaporator temperature sensor) 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 NO. 1 COOLER THERMISTOR (EVAPORATOR TEMPERATURE SENSOR)

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





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

3. INSPECT AIR CONDITIONING HARNESS ASSEMBLY (AIR CONDITIONING AMPLIFIER - NO. 1 COOLER THERMISTOR)

(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