B1413

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

DESCRIPTION

The No. 1 cooler thermistor is installed on the evaporator in the air conditioning unit to detect the temperature of the cooled air that has passed through the No. 1 cooler evaporator sub-assembly and control the air conditioning. It sends appropriate signals to the air conditioning amplifier assembly. The resistance of the No. 1 cooler thermistor changes in accordance with the temperature of the cooled air that has passed through the No. 1 cooler evaporator sub-assembly. 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 and reads voltage changes as the resistance of the No. 1 cooler thermistor changes. The No. 1 cooler thermistor is used for frost prevention.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING TECHSTREAM (EVAPORATOR FIN THERMISTOR)

(a) Use the Data List to check if the No. 1 cooler thermistor is functioning properly Scan Tool Testing and Procedures.

Air Conditioner





OK:

The display is as specified in the normal condition column.

Result





C -- INSPECT NO. 1 COOLER THERMISTOR

B -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal

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

2. INSPECT NO. 1 COOLER THERMISTOR

(a) Remove the No. 1 cooler thermistor Removal.





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

Standard Resistance:





Text in Illustration





NOTICE:
* Even slightly touching the No. 1 cooler thermistor may change the resistance value. Be sure to hold the connector of the No. 1 cooler thermistor.
* When measuring, the No. 1 cooler thermistor temperature must be the same as the ambient temperature.

HINT
As the temperature increases, the resistance decreases (refer to the graph).

NG -- REPLACE NO. 1 COOLER THERMISTOR Removal
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (NO. 1 COOLER THERMISTOR - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the C28 thermistor connector.

(b) Disconnect the C32 amplifier connector.

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

Standard Resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY Removal