Yes...as per the above drawing...the signal from the A/C or in-cab switch simply energizes the coil of the relay. Relay's draw next to no current so you don't need to worry too much about the wire size there.
The actual wiring which passes through the relays to the fan motors needs to be substantial enough to carry about 50Amps. Also...make sure the relays are rated at same (or higher).

 

Ive been using 30A and sometimes 40A Relays with no problem.. What do the fans pull on start up?

 

When we tested the '05 fans on the bench using 12 awg wire, the inrush was around 70-75 amps. Not sure what they are now.

 

Do you have tuning software Chad?
First thing I'd do is lift the rev's at idle just to see if that's the issue.
If that doesn't help...atleast you'll know to look elsewhere for the issue.

 

Sheeit, and here I thought swapping in fans would be easy.

 

I'm actually about to purchase HP Tuners. I'm pretty sure it's the idle, because if use both feet at a stop light and bring the idle to 600-650 rpm everything works fine. This is with both fans going and the a/c on. And the funny thing is, the thing now doesn't dip below 500 rpm like it used to. I'm guessing the computer is learning?

Now I need to test this at night with all the lights on and see what happens.

Thanks.

 

No, it's just me. I'm pretty sure if you were to stand around me, then you would have problems like this. Luckily this aura doesn't extend to everything.