Finished wiring a 16" Derale electric fan onto the radiator to replace the yellow clutch fan a few weeks ago. I wired it to a non-switched source. Originally, it came with a 180F on and 165F off NPT switch that I put in the NPT that was vacated when I removed the air pump stuff - A bank, rear. I have a battery kill switch in the trunk, so if I think the fan runs too long I can manually kill it, which is why I wired to the non-switched.
With that low of a shut-off and on a non-switched source, the fan ran forever and never shutoff - well at least in the 10 minutes I allowed it to kill the battery. At 180F it comes on even before the smaller, original aux fan.
I next tried a 200F on and 185F off thermostat switch, thinking that would be a better solution. Comes on after the aux fan, but still ran at least 30 minutes after the car is shut-off.
I ran infrared temperature checks as best I could and the temp after about 2 minutes of the car off and the fan still blowing, read from 186 down to 172 - which shoulda cut the temp off.
I’ve got more diagnostics to do to figure out, but the first one I thought about was maybe the temperature really does stay about 185 for a long time where I have the probe positioned on the A bank.
Pics first, then any thoughts would be greatly appreciated!