My thermoswitch is currently installed on the t-stat housing/upper radiator side. I was wondering if anyone installed it on the return side/lower radiator sie using a hose adapter with a fitting for the thermoswitch.? Which one will have a more reliable temp reading?

 

Most relevant place for fan control is exiting the radiator, that tells you the temp going into the block regardless of the efficiency of the radiator. You could be hammering your car hard pumping out 210 degree coolant but after going through the radiator it could be back down to 175. You don't want the fan running in this situation, because the air passing through already is doing its job.

I went with this controller on my build. It has a sensor you stick to the bottom of the radiator and it only spins the fan as fast as needed to maintain the desired temp and it's completely adjustable.

https://derale.com/product-footer/el...n-probe-detail

 

Thanks, Chuyler for the input. The Derale fan controler looks like a good addition in my future "to-do" list. For now I will try putting my thermo switch on the return hose with my adapter.

 

Is it adjustable? What temp is the switch supposed to open?