Electric fan - switched lead, or on all the time?

I put an electric fan on my Celica. Right now I have it wired straight to the battery. Is it best to put it on a switched lead, or let it run after the car is shut off?

I'm thinking about putting a relay in to shut it off at WOT. Anyone ever done that?

Thanks,

Ed

i am assuming you have some sort of thermal switch on it already..... and if so, either way works, but it was my experience on my truck that when the truck was especially hot in summer driving the fan would run off and on for a really long time when the engine was shut off. and this drained the battery making it difficult to restart. especially with a heat soaked AND depleted battery.

Yes, I got a thermal switch with the fan.

That's a good point- I didn't think about it cycling on and off several times. On a heat soaked engine it's probably almost sure to happen.

I'd use a relay between a thermal switched source and a key switched source so both need to be feeding 12V+ to the relay to fire up the fan. Don't forget fuses.

I have a fan wired in with a relay circuit I purchased from Summit Racing. When I shut the car off, the fan runs until it hits 180 degrees. It doesn't cycle on/off at all. Don't have any battery trouble either, at least until the battery gets some age on it. You could probably find a timed switch somewhere that would run the fan for a few minutes and then shut it off.

how much help will the fan be i the coolant is not flowing... on my jeep I had mine wired with a thermal switch with key on and an override on. not sure i ever used the override except when wheeling. and then only as a precaution to turn it on early.

The one in the RX-7 I wired through the ignition switch with a relay.

The one in the Abomination is powered from the battery kill switch, but not through the ignition switch. It doesn't usually come back on after it shuts down. I don't think it really matters.