Evaporator Temperature Sensor / Switch: Testing and Inspection

Fig. 17 Thermistor test:

1. Remove thermistor from evaporator case.
2. Immerse thermistor sensor in water as shown in Fig. 17, and connect suitable ohmmeter to thermistor.
3. Note water temperature and thermistor resistance, then add ice to lower temperature.
4. Observe thermistor resistance as water temperature decreases.

Fig. 18 Thermistor test specifications:

5. If thermistor resistance does not change within ranges shown in chart, Fig. 18, thermistor is defective. Intersection point of water temperature and measured thermistor resistance should fall between lines on graph, Fig. 18.