Correct me if I'm wrong,
but doesn't turing on the AC turn the fan(s) on?
And I think he's looking for a way to turn the fan(s) on between runs at a track, not while driving.
I beleive its a high signal that turns the fan relay on.
A simple switch inline between the battery and the fan power line will work, wouldn't be good if the ECU decided to activate the relay while the switch was on, send 24V instead of 12V to the fan and fry the motor.
I use this setup at the track, between runs on shutoff the car and turn the fan on.
