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.
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| B1413/13 | Open or short in evaporator temperature sensor circuit |
|
WIRING DIAGRAM
INSPECTION PROCEDURE
PROCEDURE
READ VALUE USING INTELLIGENT TESTER (EVAPORATOR FIN THERMISTOR)
Use the Data List to check if the evaporator fin thermistor is functioning properly.
| Tester Display | Measurement Item / Range | Normal Condition | Diagnostic Note |
|---|---|---|---|
| Evaporator Fin Thermistor | Evaporator fin thermistor / Min.: -29.7°C (-21.46°F) Max.: 59.55°C (139.19°F) |
Actual evaporator temperature is displayed | Open in circuit: -29.7°C (-21.46°F) Short in circuit: 59.55°C (139.19°F) |
| OK |
|---|
| The display is as specified in the normal condition. |
| Result | Proceed to |
|---|---|
| NG | A |
| OK (Checking from the PROBLEM SYMPTOMS TABLE) | B |
| OK (Checking from the DTC) | C |
| B |
|
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Click here |
| C |
|
REPLACE AIR CONDITIONING AMPLIFIER Click here |
| A |
|
INSPECT NO. 1 COOLER THERMISTOR (EVAPORATOR TEMPERATURE SENSOR)
Remove the No. 1 cooler thermistor (evaporator temperature sensor) connector Click here.
Measure the resistance according to the value(s) in the table below.
| Standard resistance | ||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Note
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.
Tech Tips
As the temperature increases, the resistance decreases (see the graph).
| NG |
|
REPLACE NO. 1 COOLER THERMISTOR Click here |
| OK |
|
REPLACE AIR CONDITIONING HARNESS Click here