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 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 air conditioning amplifier. 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 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 (EVAPORATOR FIN THERMISTOR)

(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 Electrical / Air Conditioner / Data List / Evaporator Fin Thermistor.

(e) According to the display on the Techstream, read the Data List.

Air Conditioner





OK:

The display is as specified in the normal condition.

Result





C -- REPLACE AIR CONDITIONING AMPLIFIER Removal

B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Problem Symptoms Table
A -- Continue to next step.

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





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

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

Standard Resistance:





HINT
- Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor.
- When measuring, the sensor temperature must be the same as the ambient temperature.
- As the temperature increases, the resistance decreases (See the graph).

(c) Reinstall the No. 1 cooler thermistor (evaporator temperature sensor) connector.

NG -- REPLACE NO. 1 COOLER THERMISTOR (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:





(c) Reinstall the air conditioning harness.

NG -- REPLACE AIR CONDITIONING HARNESS Disassembly

OK -- REPLACE AIR CONDITIONING AMPLIFIER Removal