Sensor in radiator


I’ve been searching around trying to figure out what it is and the best I can come up with is that it somehow controls a fan or something but since my car has (well, had) a mechanical fan I’m not sure what the point of it is. Does it have something to do with the air conditioning system?

The radiator the previous owner installed has two sensor ports on the side of it so I’d like to use one to trigger an electric fan and then maybe I’ll eventually wire up a coolant temp sensor so I can see radiator outlet temperature along with engine out temperature just because.


It control the AC fan for when the car started to run hot. Some cars have 2 sensors for a low and a high and others have 1 with the low/high built in.


Don’t use automatic stuff. Everything that is supposed to automatically do things…one day won’t. And it will happen when you’re idling at a red flag with a very hot engine, or when your car is idling in the paddock on a cold morning for an hour. You can depend on you. Everything else is iffy.


I was planning on having a switch to control the fan manually but also adding in a temperature switch so that it’ll come on automatically in case I forget.


That’s not a crazy solution but it does add complexity.


I used the thermo switch in the radiator to turn on my electric fan and added a toggle override switch in the cockpit. It wasn’t too difficult.