right now i got my fan on a switch that i manually turn on and off for when i'm at the track i can let it blow while i'm waiting in the staging lanes, but recently the relay has been getting really hot and today it burned out the switch.

what i'm wanting to know is where or how would i hook up the fan to come on automatically when i start the car so i can eliminate the switch and not screw anything up

 

I would use a remote thermostat in the control circuit and wire the relay up to the key switch (to the coil in the relay). It will cut the fan off when the tempature is below the set limit. It may be that the relay you were using is too small (40 amp) and this is why it is toasting. The other thing that that melt these is low voltage (volts down/amps up). Some of the high output (4000+) fans will require over 40 amps to run and I have seen these over the 50 amp range. The amp draw may be on the fan tag. Good connections is a must as these can create resistance and increase the amp load.

 

Buy THIS first (or something like that), then wire it up like this:



dont forget to put fuses on both of the power lines going into the relay. Using a relay like this takes the load off of the swith so you dont burn up another.

You dont have to join the grounds like it shows in the pic, but I drew it that way to simplify it.

I know also that the link that I posted says its for a water pump, but it works perfect for the fan if you use a relay like I am showing you. If you try to run the fan through the water temp switch with out a relay, you will likely burn it up.