dual electric fans....2 relays or 1?
 

got my dual 16" fans mounted and im ready to start wiring them up. i will be using a temp switch in the drivers side head to provide a ground. do i need 2 relays?

Re: dual electric fans....2 relays or 1?
 

I would use a relay per fan. It sucks big time when your wiring or relay melts down on a trip. Been there done that.

Re: dual electric fans....2 relays or 1?
 

does that mean use 2 temp switches too or would 1 provide sufficient ground for 2 relays? thanks

Re: dual electric fans....2 relays or 1?
 

I used one temp switch on one, and then I hooked the other in line with the a/c clutch so it would come on when the a/c is on. I also hooked the 2nd fan in to a wire that I can toggle in the cab that allows the 2 fans to work as one through the 2 relays that way if I was towing and the a/c wasn't on I could still have 2 fans.

Re: dual electric fans....2 relays or 1?
 

Yes, like Dieselw said. I just installed a dual 11" fan setup in a customers car, and used all SPAL fan stuff. Dual fans, and their PWM fan controller. Worked great. The controller works like one relay, and their instructions said to use an additional relay to power the other fan. The controller is programmable for you to set turn on and turn off temps, using one temp switch. If you go to their site and click on the PWM, there will be a download with instructions to install. They also recommend a toggle switch for an override, just in case of a failure. I spoke to them when I had a couple of questions, and they were very helpful in helping me understand their product. I would use this setup again.

Re: dual electric fans....2 relays or 1?
 

Here's a diagram. It only has one fan but the second one would be easy to add and I would run a second relay also. That way you would have a back-up in case one failed. Where are you mounting the temperature gauge sender?

Re: dual electric fans....2 relays or 1?
 

either drivers head or drivers side intake passage

Re: dual electric fans....2 relays or 1?
 

...and keep a spare relay or 2 in the glove box. Cheap insurance when a relay goes bad.