Evaporator Temperature Sensor Circuit - Air Conditioning System

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

DTC 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 temperature of the cooled air that has passed through the evaporator and to control the air conditioner. It sends signals to the air conditioning amplifier, which change in accordance with the resistance of the No. 1 cooler thermistor (evaporator temperature sensor). As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases. The air conditioning amplifier applies a voltage (5V) to the No. 1 cooler thermistor (evaporator temperature sensor) and reads voltage changes as changes in the resistance of the evaporator temperature sensor. 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 tester on.
(d) Select the following menus: Body Electrical / Air Conditioner / Data List / Evaporator Fin Thermistor
(e) According to the display on tester, read the "Data List".
Data List / Air Conditioner:






OK:
The display is as specified in the normal condition column.
Result:






C -- REPLACE AIR CONDITIONING AMPLIFIER
B -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
A -- Continue to next step.
2. INSPECT NO. 1 COOLER THERMISTOR (EVAPORATOR TEMPERATURE SENSOR)




(a) Remove the evaporator temperature sensor.
(b) Measure the resistance.
Standard resistance:





NOTICE:
- Touching the sensor even slightly 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.
HINT: As the temperature increases, the resistance decreases (see the graph on the left).
(c) Reinstall the evaporator temperature sensor.
Result:






C -- REPLACE NO.1 COOLER THERMISTOR (EVAPORATOR TEMPERATURE SENSOR)
B -- REPLACE NO. 1 COOLER THERMISTOR (EVAPORATOR TEMPERATURE SENSOR)
A -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (No. 1 COOLER THERMISTOR - AIR CONDITIONING AMPLIFIER)




(a) Disconnect the E2 No. 1 cooler thermistor (evaporator temperature sensor) connector.
(b) Disconnect the E8 air conditioning amplifier connector.
(c) Measure the resistance.
Standard resistance:





(d) Reconnect the No. 1 cooler thermistor connector.
(e) Reconnect the air conditioning amplifier connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE AIR CONDITIONING AMPLIFIER