Hello,

The car came to me with an unpluged temperature switch, bypassed, meaning the radiator fan is always running.
It was fine for me for a while until the radiator fan motor melts due to overheating. I replaced the radiator fan together with the bad temparature switch.
As I start the car from idle, as the temp goes into a hot state, the radiator fan starts to spin, and as the temp cools down the fan also stops. I concluded that the cooling system is working. Now, I drove the car on the street, it doesn't work as I expected. The car goes into a hot state and the fan is not spinning. I suspect that temperature switch is not working when the engine is too hot (close to overheating). Because again, when I started to re-do the scenario it does work in idle state; the fan runs when it has to.
My problem is how can I say that the temperature switch is defective when it is working in idle.

Thanks for any help.