Electrical Coolant Temperature Sensor Functionality

[Sbasham1]

I am trying to understand how the Coolant Temperature Sensor operates (attached photo).

I'm wiring in an electric radiator fan after the second time my mechanical fan destroyed a radiator. I need to install a temperature switch that turns the fans on and off once the engine is up to a certain temp.

I can find a boat load of information about the Temperature Sending Unit to the temp gauge, but no information about how this sensor operates. I've let this heat up and get 0 ohms resistance and 0 volts, so I'm guessing that as it heats up, it closes a circuit.

Can someone please help me understand how this operates and if it would be sufficient to switch a relay on and off at temp?

Thanks!

 

[Sbasham1]

For the future readers in the same spot as myself:

I sat with an ohmmeter on it for 10 minutes while it ran and heated up and after it shut down and cooled down.

The Coolant Temp Switch generated 0mV at all times from cold soaked, to heat soaked, to cold soaked.
It also had infinite resistance (open circuit) until it reached some unknown operating temperature after ~3 minutes of running. From there it closed the contact and kept a steady 0.1 ohms resistance (so doesn't function like a sending unit with variable resistance). Then after shutdown as the engine cooled down it opened the contact again and went back to infinite resistance.

I plan on using this as an electric radiator fan switch. I'll try to report back with temperature readings for shut down and start up if I get my hands on a IR thermometer.

 

[RiverandSand]

An IR heat gun is a good choice to find the temp at which the switch closes to complete the circuit. That will help you decide if it is the right temp for your needs. HF has them and won't cost you an arm and leg. My electric fan comes on at 195, my t-stat opens at 185. My sensor has the temp stamped on it.