Thermo Fan switch

The Thermo Fan Switch is designed to control operating of the electric thermo fan. Thermo Fan Switch responds to changes in engine coolant temperature, providing circuit switching during a predetermined temperature range allowing for operating.

The Thermo Fan Switch shown in container of heat water for checking.

This switch is open at 90 degree .

Does the fan switch meet the manufacturer,s specification? why or not?
Yes it is this is an open circuit switch once it reaches to a certain degree (temperature) it closed and start to work.

Is this a thermistor?
No it is not because when the temperature reach to 90 degree then the switch work (close the switch ) and the fan works that way we can say this is a thermo switch.

Explain the internal operation and why your resistance changes?

The thermo fan switch is mounted on the face of the radiator core. this type an electronic thermal switch as switch that detects the cooling system temperature its usually adjustable from about 80 degree to 99 degree.

How it change resistance?
When the the temperature on cooling system is getting high the resistance decrease and the switch is close depends on manufacturer specifications.