Radiator Cooling Fan Temperature Sensor / Switch: Testing and Inspection

1. Remove thermo switch from radiator.
2. Place temperature sensing portion of thermo switch in a container of water.
3. Connect ohmmeter onto thermo switch terminals.
4. Heat water.
5. When the temperature of the water reaches approximately 180°F-190°F, continuity should exist between thermo switch terminals.
6. On 1989 models, allow temperature of the water to drop to between 162°F-183°F. No continuity should exist in this range.
7. On 1990-92 models, allow temperature of the water to drop to between 167°F-178°F. No continuity should exist in this range.
8. On all models, if thermo switch does not operate as specified, replace thermo switch.