Radiator Cooling Fan Temperature Sensor / Switch: Testing and Inspection

1. Remove thermo switch from radiator.
2. Place temperature sensing portion of the thermo switch in a container of water.
3. Connect a suitable ohmmeter onto thermo switch terminals.
4. Heat water.
5. When the temperature of the water reaches approximately 190 degrees F, the thermo switch contacts should close (thermo switch activated) as indicated by a deflection of the ohmmeter needle.
6. Allow the temperature of the water to drop to 167 degrees F. The thermo switch contacts should open (thermo switch deactivated) as indicated by a deflection of the ohmmeter needle.
7. If thermo switch does not operate as specified, replace thermo switch.