Hey everyone,

Im having some trouble getting these damn things wired right. Ive got a 91 F250 with a 7.3L. Im trying to wire a set of dual fans straight to a toggle switch in the cab. Its retardedly simple yet i can seem to get it right. ive got them hooked up and running but the wires and where they connect to the switch get hot. i havent run them for more than 10 minutes because im afraid something will catch fire lmao. Does anyone have the wiring for a dual fan setup?! Ive checked the FAQ page but cant seem to find what i need. Any help will be appreciated!

 

oh wow.yeah you'll burn her up if you try that much more.you need a fan controller or if you want to use a toggle (or two) then you'll need some relays.
the problem with the relays is,that the fans spike really high when you first turn them on.so normal 30/40 a relays just don't last.
so here's what i suggest for your manual control method;

get two of these:

those should hold up well and take the spikes.once the fans are on,the amp draw way below the spike.use 10 awg wire for the relay's.
rather than fuses between relay pins #30,use a section of fuseable link for each one instead.
now for the line(s) to the toggle(s) that could probably just be speaker wire lol.use a light gauge 18.it will just tell the relays to open/close between the battery and fan with no load on it.and you won't burn the truck down.



so if you want just one toggle,hook your two 86#'s together at the relays and run just one wire to the toggle switch.i would run two lines and have two toggles myself because i know the duals on high can be a bit overkill for most of the time.being able to just spin one at a time sure would be handy.
so from pin 86's to the toggle,and at the other side of the toggle,a switched on 12v power source.like tapping into the radio's key on/run feed would be a good choice.if you use an always hot line,then you could mistakenly leave the fan(s) on when exiting the truck (though you'd hear them anyway and flip it off i suppose.i just wouldn't risk it.)

 

Thanks! I ordered those relays should be here in a couple days. Well see how it goes lol

 

Dont necessarily need a controller, but i HIGHLY recommend one. You cant run them straight to a switch they will catch on fire. You have to run them through a relay. I ran a typically headlight relay with a 40A maxi fuses through a cheapo Orielly controller.

 

Don't use the one from champion radiator. Failed me twice now. Pos

Great rad
Terrible relay

 

You can run them through a simple switch IF, your wire is big enough and the switch is big enough. That's why most people run relays, to avoid the very large wiring and the very large expensive switch(s) you would need.

So the relays are a good idea and what you should use to make it work, but your system would have worked with a little bit more figuring and load calcuations.

 

Just got the relays in the mail! Got some 10 gauge wire and decent switches. I'll let ya know how it goes!

 

Alright i just want to get this as clear as possible before i start. I got 2 relays and 2 switches and some 10 gauge wire. So i am going to run both power wires from the fans to pin 87 on the relays. Both negative wires from the fans to a ground i.e. the negative on the battery. Pin 85 gets connected to the negative on the battery. Pin 30 gets connected to the power on the battery. and Pin 86 gets run to the switchs. Then i have to run a keyed power to the switch as well i.e. run to the fuse for the radio? so assuming all that is correct lets let to the switches. I got 2 30 amp led switches. They were the biggest ones the parts store had lol. They have 3 prongs on them top middle and bottom. so im guessing the wire from the relay goes to the bottom and the hot wire goes to the top? sorry for all the questions im just trying to get this right so these wires dont burn up again!! Thank you!

 

right.so one power line of the fan to pin #87 of one relay.
the other fans power wire to the other relay,also pin #87 of that one.
each ground wire of fans,hooked to ground.clean frame or negative battery post (same thing.)
both relay pins #85's get grounded as well.

pin #30 gets battery power,but make sure you have a fuseable link right at the battery post,hooked to the 10 awg wire to pin 30.
same goes for the other relay.a devoted fueable link off bat,to it's 10 awg wire to the other one's pin #30.
(see those fuseable links on the fender mounted starter solenoid? if you think two ring terminals carrying 10 AWG wires could fit under the nut with those,you could install them there for a cleaner install if you want,rather than off the batteries.)

for pin #86
find the power going to the radio.make sure it's only got power when the key is on and with the engine is running.
with this line,run two pigtails off so you can feed each switch a feed (keeping the radio still fed too of course if you like music lol! your just borrowing a tiny bit of power to trigger some relays.it'll never know your there. )
the other side of the switches, one goes to one relays pin #86 and one goes to the others pin #86.
if the toggle also has a ground pin,then feed it a ground too.there should be a wiring diagram on the package of the switch to know which are the two positives and the ground pin.

 

Hey Ford thanks so much for the info!! It took me a couple hours to get all the wiring run correctly and get everything looking pretty but it works great!! I put almost 60 miles on it tonight and of course i didnt even have to turn the damn fans on once lol. But i ran em for a good half hour at the house at idle and everything seemed great, no hot wires or switches this time!! Thank you again for all your help!

 

no problem.yeah just driving down the road especially this time of year,you'll hardly ever need 'em unless you've got a plow on.that's good though being all setup for the summer now.

 

You could just splice the positive wire from 1 switch to both relays signal pins, i read that someone hwo did this made a comment that if its hot weather and/or in car cues and with the AC on they got it several degrees cooler, just wondered if you have tested this ??

 

Just a heads up guys, there are some nice 70 amp relays in Ford Focuses and Crown Vics. I was at the junkyard the other day and picked up 5 and a bunch of fuses for $5, and they aren't made in china junk. Glad you got that fan installed and wired up, I love mine.