I currently have an HHR fan on a Be Cool radiator that the core size is 27 x 18. So this fan leaves a lot of the core uncovered. It seems to work great at the track and allows quick cool down between rounds, but on the street I am having problems once the outside temps get over 85. Thinking of switching to a dual fan set up to cover the entire core area. My question is can I add a second relay for the second fan and run them both through the one switch that I currently have or do I have to have two switches?

I would set up the 2nd fan on a temp switch and relay to come on when one fan will not keep up.

" do I have to have two switches?"
No you do not have to have 2 switches. One can easily handle 2 relays!
MIke
p.s. I have one switch that turns on my 2 fans on ONE relay and the SAME switch also turns on a separate relay for my water pump.

Yes, you can wire a second relay to close with the one switch. Current draw on the relay coil winding is small, typically one to three amps. So you can run the second relay in parallel with the first.

The trigger on relays doesnt draw much at all(very
small amount) so yes you can

I have 2 fans on 1 switch through a relay.

Fans are 26 amps to start and 21 to run. The relay is a 60 amp from Radio shack, so my amperage is less than 1 amp through the switch.

I went through the same thing and made a shroud, which helped. If you buy one of those kits, you'll wind up "making" a shroud anyway, with all the cutting.

I use a 2500 cfm puller and a small pusher between the grill and radiator.

I use separate switches & relays for my fans.If one craps out I still have one working and a shot at getting home

I can tell you that 2 fans may not work with 1 controller that can control 2 fans.
I have a ford contour dual fan setup and it melts the hayden controller designed for 2 fan setup. I guess it pulls to many amps for it. I have tried 2 of them with the same result. So I wired mine with a toggle switch that controls the ground.

2 relays 1 switch, yes. All of the current will go through the relay contacts. The only current going through the switch is the relays coils which is very little. You do however have to make sure the relay contacts are rated high enough for the amps on the fans.

Thanks for all the replies! I was pretty sure it shouldnt be a problem, but wanted to make sure. Currently have one 50 amp relay and will order another one this week.

Perhaps this may be the ticket. EBay Item 171049890081 if the link doesn't work.

http://www.ebay.com/itm/171049890081;jse...1#ht_253wt_1024