i got a big *** electric fan off my friends 04 cherroke after she smashed it up. there was only one tab broken off it so. its big. has to be at least 22 inches. i made some custom mounts and with alittle hammering and repositioning i managed to mount it in between the ac condensor and the radiator. so im hoping my ac will be alittle cooler and so will the raditator since its pulling through the ac and pushing into the radiator. i was somewhat dumb and forgot to take pics but ill see if i can get a few. right now im just gunna wire it up as a secondary fan for offroading and those hot summer days sitting in hours of traffic on the way to the shore.


now heres where i feel really dumb.... how do u hook up a relay? lol i know one wire goes in from the battery in and then out to the fan and other otherone goes from power to the switch and back to the relay but whats the 4th prong for? Ground? also do u put the fuse after the relay or before?

 

It's a drawing for lights but the relay wiring will be the same. And yes you do need to ground a relay.

 

Lets call the posts on the relay 1 2
3 4

so lets say side 1 is the high current side (fan) and side 2 is the switch sde. 1 and 2 have a 12 volt positive. usually from the battery. 4 goes to your switch. 3 goes to the positve side of your fan. And you fan should be grounded through your core support or any other good ground. You can put the fuse anywere you want , but put it infront of the relay that way you protect the relay as well.

 

thanks that perfect.

 

I am using a old style starter solenoid. I got it for 10 bucks at Advance.It has two mounting holes. All you have to do is power the s terminal on the solenoid with either ignition switched 12v or constant 12v through a switch in the cab. The coil is grounded through the mount. The two big terminals make and break the fan supply voltage. If you have a large fan, and choose to use a relay make sure that it is rated for the correct amperage. A starter solenoid is designed to carry the amperage necessary to start an engine. I was going to use a relay, then I saw one of shott's posts about using the solenoid.

 

Also, at 12v a 22" fan is going to draw a good bit of current. You may want to look into using a start up capacitor to lighten the load.

 

becarefull.. most 30/40 amp relays may burn out quick after time b.c of the high startup amperage. each of my two 16" fans ring out just over 50-60 amps apeice for a split second during startup.. normal running are between 15 to 20 a peice..

may want to think about using some 100 AMP starter selonoids... im using two right now and for over a year of startups they have been fine..

also DC motors (the electric fan motor) turn into generators as they free spin. and mind you when the fan is off and your driving down the road the wind will be turning that fan.. a few diodes placed between the neg and pos wires of the fan will eliminate this backfeeding of power back towards the relay/selenoid