Keep it simple:
1-Wire both fal fans to ground and connect their +'s to the stock fan +'s.
2-connect one side of your interior switch to ground and run the other side to the two fan activation pins on your ecu. If you want two seperates then run two switches. It won't hurt the ecu but if you're worried, cut the wires before the go into the ecu and tape them. This will work unless the large stock positive wires that normally power the fan are disconnected somewhere.
Piece of cake. Then you'll be using the factory fan relays and fuses. Just don't forget to use the switches
Orrrrrr.....
Get a spdt 12v automotive relay:
-wire pin 85 to the ignition 12v+ coming from your key switch
-wire pin 86 to ground
-wire pin 87 through a decnt fuse (20A) then to the battery +
-wire pin 30 to the + of one fan
-ground the fan directly to the frame
I'd put the relay right by the battery so the 12v path is shorter and everything will run cooler. Then you only need to run the one activation wire(pin 85) to ignition in the car. Or you could wire pin 85 to one of the fuses under the hood that only gets 12v with the car on, and save some wire.
Now whenever the car is on, the fan will be running. Problem is, the fan will wear out much quicker like this. If you wanted, you could wire in an extra idle switch that only lets one of the fans come on at idle. You could also use the a/c compressor power to turn on a relay to power the second fan. Possibilities are endless with relays.
