Thermo Fan Switch

Its very important that Thermo fan switch works properly on every car as it used to turn on radiator cooling fans. When vehicle driving on a highway radiator cools down with upcoming air stream, but when its in a traffic jam and only short starts and stop, that when that sensor very important. Its a few type of that sensors, one will complete the circuit when hot enough, another will do an open circuit when at certain temperature.

Here is a pictures showing that at 92 degrees TFS open circuit, so that means if engine will get to 92 degrees, fan will start working until temperature drops below 92 degrees.