Radiator Cooling Fan Temperature Sensor / Switch: Testing and Inspection

Fig. 28 Testing Thermo Switch:

1. Remove thermo switch/sensor, refer to COMPONENT R&R PROCEDURES/THERMO SWITCH/SENSOR.
2. Connect suitable ohmmeter across switch terminals, then immerse lower part of switch in water, Fig. 28. Ohmmeter should indicate an open circuit.
3. Heat water until temperature reaches approximately 212°F. Switch contacts should close and the ohmmeter should indicate continuity.
4. If switch does not operate properly, replace it.