i got an electric fan out of a junked fwd car, my question is though, do i want this on a toggle switch? how often does it have to be on. it is supposed to be on anytime the car is on? or do i watch the temp guage and then turn it on..

 

get a probe. that way the fan is only one when needed. i got mine for $35 at pepboys. its preset for 185*. my thermostat opens at 180 and if the water gets to 185 the fan turns on

 

On the harness that goes to the ignition coil on your car, I think the middle wire gives a steady low voltage when your key is in the II position, it is basically just a message that the car is on the "on" position, you can tap the switch to that wire, use a multimeter to see which one it is. Don't worry, it would not affect your ignition coil because the switch requires very little power, only enough to power a few small magnets to switch the relay to the on position so it is negligible. That will have your fan on whenever the car is on. If you want to go the thermostat route, that is prefered, my way is the lazy way.

 

i like the sounds of "lazy way"

 

you need a bosch relay... 85=block grounded temp switch., 86/30=battery, 87a=fan pos.... and put fan neg on chassis ground..

 

alan would know how to answer this thread

 

87 AMPS??? I think that's a little overdoing it. As long as it's a single motor fan, a 30/40A standard relay is fine.

 

A 35/40 amp relay is not enough!!
Here is a good article on how to wire one up with diagrams

http://www.fordmuscle.com/archives/2...an/index.shtml

 

i was just gonna run a neg and pos from the fan to the battery but have a toggle switch in the middle of the pos wire.... wouldnt this work?

 

no, because you will definately melt something, you need to use a relay...



a relay has 5 pins 85 86 87 87a 30 .....

85=ground
86=power
87=closed output
87a=open output
30=input

85/86 provide the relay power
whatever is hooked to 30 will come out of 87 when the relay is off and 87a when the relay is on....