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I want to wire up my dual fans so that I can turn them both on at the same time by using a toggle switch. Can somebody please explain exactly how to do this step by step? I have a 30 amp LED toggle switch that I will be using. I searched but couldnt find what I was looking for. The switch has three connections on it (Power, Lead, Ground) and I need to know what wires go where. Also, do you have to use a relay in this set up or not?
Last edited by 85Iroc-Z; Nov 10, 2008 at 10:41 AM.
Here is how I wired mine using a SPST relay: Hot from battery to relay. Hot from under dash (acc at fuse block) to toggle. Toggle to relay. Relay to ground. 30/87 should be your contacts and 85/86 should be your coil.
Heres my quick 10 minute MS Paint wiring diagram. I would recommend using ignition power for the relay coils, so you can't accidentally leave your fans on and run the battery dead. Note that the switch controls relay coil ground, not power - this is safer (and easier) since you only have to run a single ground wire into the cabin to the switch. Also note that I'm showing 2 fuses, one for each fan. That way, if one fan shorts/fails, the other should still run and get you home.
I realize that many members use a toggle switch--and no doubt are satisfied with that approach. I didn't wish to be troubled with remembering to turn on/turn off (I know myself well enough to know I'd eventually forget), but I did want both fans to work together, so here's what I did:
i have one main question:
why do u want dual fans on one toggle switch.
reason for my question:
i have an 87 5.7 iroc with 113k miles and even in the summer i hardly had to use both fans. If i stopped at a redlight or parked for a min then id have to turn on one of the fans.... if i sat too long then i would def have to turn on both of the fans but thats only if the water gauge would get to like 250 which i cringe whenever i see it stray from 150-180.... not that i really know what these should run at lol
Could I use the factory dual fan relay? If not, what should they be, 30 amp relays?
I would just use automotive 30 amp relays. I used 2 of them when I put dual e-fans on my truck. The OEM fan relays take a special GM connector, and cost about $10 each. You can get the 30A relays at radioshack for a few bucks each, and they will connect to a normal female blade type connector. Each cooling fan should only draw around 10 amps, but using a 30 amp relay gives you plenty of margin to work with, without fear of burning the relays up.
I probably should have also noted in the diagram that the fan power wires need to be fairly heavy, 12 or 10 gauge wire should work fine. The relay coil wires can be smaller, 16 gauge or so.
Also, I would mount the relays fairly close to the fans themselves, like on the inner fender, or core support. The idea is to make the high current draw wires as short as possible, again to minimize risk of fire.
So I need 2 relays with 4 prongs on them each (2 ground, 2 power)? I just decided to put both of them to one switch so that it would cool down real quick when it got hot, and they wouldnt have to stay running as long. What would be better about wiring them to two seperate switches?
[QUOTE=85Iroc-Z;3948705]Can anybody show me pictures of how they wired their dual fans to one toggle switch, and how the wiring to the relay went?
On my 1992 blazer 350tbi I am trying to run dual fans to a switch also in not sure if I need two relays and two switches or if one relay and one switch would work I just want it to be done right so can you guys out there give me any clues of how i need to wire it or the best way to go about converting it plez thanks
Here is a typical dual fan wiring setup. Your ecm will not support the control on the primary fan. You can use a cylinder head temp switch like a sw555 to control the ground side of the relays.
