My electric fans are switched on with a relay that is activated when the ignition is on. I got tired of it running all the time just because the ign. was on. I bought a thermal switch that has a probe that inserts into the radiator. I got it mounted and decided that if i just run it by itself, it would probably run when the car was off which i don't really want. So i decided to run the ground wire of the realy through the thermal switch. Is this ok? The only time the fan could run was if the ign. was on and the thermal switch closed the realy circuit... only reason i ask is because the instructions on the thermal switch said not to run a ground through the switch. I couldnt not see anything wrong with that

There are many ways to control electric current, so as long as the fan comes on when the engine is hot and running, you should be just fine. Your major concern should be that the relay and wiring that actually controls the fan motor current is properly sized and supplied.

Just took it for a drive. Fans didnt come on until i parked at starbucks and idled for about 5 minutes. I heard them kick on for about 30 secs. and then turn off... keewwwl! I did it!