I have an 11" dual fan setup from Spal and I'm wiring it up with dual relays according to their spec sheet. The only difference is that I reused the temperature switch I had already (dual prongs) instead of buying a new one from Spal (single prong).

My question is I was trying to test the setup without running the car by jumpering across the switch using a heavy guage wire. Shouldn't this turn on the fans as I'm assuming that this is what normally happens when the switch closes? I had the ignition on and their was switched power to the temp switch. Jumpered across the prongs and nothing happended, no relay clicks, no fan going on. I checked the fuses and also directly running the fans off the battery to make sure they work. So am I wrong in my assumption about how the temp switch works or am I missing something. Are the relays I have not made for use with the dual prong style switch? I guess thats another question I have. How does the signle prong switch work if there is no juice and only 1 wire going to it?

A single prong temp switch is designed to ground the relay coils. Your switched power wire should go to the positive side of the relay coils. Make sure nothing else is connected to the positive side of the coils. Take a wire that is grounded to the engine or chassis and connect it to one prong on your temp switch and a wire from the other prong on the temp switch to the negative side of the relay coils. Hooked up this way the fans should run when you jumper the prongs on the temp switch and turn on the ignition.