How to wire slim fans with a relay

[awdmonster1904]

I wired my 2 spal fans to the stock hardness but they pull too much current and melted my plug
How can i wire them to a relay using power from the battery but still have them come on with the thermo swich ?

 

[mheidemanjr]

its very esy get a 4 pin relay and it will be numbered 85 86 87 30

1-run a hott wire from the battery to the number 85 pin
2- take thermo(stock fan ground wire coming from the thermo switch) negitave and wire it to pin number 87
3- take the postive wire that runs to to fan and splice in between pin 30 and 87
4- ground the fan to common ground(ie frame or nut that on the frame)
5- bada-bing done!

http://www.mp3car.com/vbulletin/imagehosting/12527647e873c2b6c2f.bmp

 

[awdmonster1904]

its very esy get a 4 pin relay and it will be numbered 85 86 87 30

1-run a hott wire from the battery to the number 85 pin
2- take thermo(stock fan ground wire coming from the thermo switch) negitave and wire it to pin number 87
3- take the postive wire that runs to to fan and splice in between pin 30 and 87
4- ground the fan to common ground(ie frame or nut that on the frame)
5- bada-bing done!

http://www.mp3car.com/vbulletin/imagehosting/12527647e873c2b6c2f.bmp

what if the relay has another 87a like 87 and 87a like a 5 pin relay

I dont understand step #3 possitive wire that goes to the fans ? and splice?

 

[doroyce05]

should he use 2 relays for the 2 fans? i have both of my fans being controlled by 1 relay and a 30amp fuse. everything was working good untill it started to run the wires hot and pop goes the fuse. i mean imagine having no fans in texas heat. im going re wire everything with 2 fuse (20amp), 2 relays going to 2 fans. im hopping this will keep the fuse from popping plus less work for these relays.

as for wiring up the relay, google a typical relay wiring. i found this which should give you a very good idea Relay Wiring

 

[96_killer]

should he use 2 relays for the 2 fans? i have both of my fans being controlled by 1 relay and a 30amp fuse. everything was working good untill it started to run the wires hot and pop goes the fuse. i mean imagine having no fans in texas heat.

100s mostly every day

I used one relay before it completely melted and I over heated in traffic. siting on the side of Loop410 when its a 100 degrees out side is not fun!!! now i use two relays and have had no problems.

 

[doroyce05]

100s mostly every day

I used one relay before it completely melted and I over heated in traffic. siting on the side of Loop410 when its a 100 degrees out side is not fun!!! now i use two relays and have had no problems.

well with this info, i'm sure that i will do 1 20a fuse and 1 relay per fan with 12 gauge wires. i dont want to expirience that man.

 

[mheidemanjr]

"what if the relay has another 87a like 87 and 87a like a 5 pin relay" thats why i said to get a 4 pin relay

as far as step 3 goes think of pin 30 and 87 as the input and out put to a toggle switch , the positive wire that comes from the fan to supply juice will get hook to those pins!
yes 2 fans +2 relays and one fuse will work just put it in the supply wire from the battery step 1

 

[draculia]

Pins 85 and 86 are for the coil in the relay, one gets a ground, and one gets a voltage source. Most relays can be wired either way, 85+ 86- or 85- 86+, however, if the relay has a diode in it, it has to be wired a specific WAY noted by the manufacturer. You don't need big wires for the coil, even if you're driving a lot of current through the main pins.

Pins 30, 87, and if its a 5 pin relay 87a are the main pins. Pin 30 is connected to pin 87a any time the coil is not active. Pin 30 is connected to pin 87 when the coil is active. You will not use pin 87a for your application if you use a 5 pin relay. Batt can go to either pin 30 or 87, and the other goes to the fan positive.

So the ground wires to your fans will go to a chassis ground, any one will do.
The positive wire for the fan will go to either pin 30 or pin 87.
Which ever pin you didn't use, pin 30 or 87 will go to your fuse.
From the fuse goes to the battery.

Alternatively, you could be the special kid and wire the positive fan wire to a fuse.
The fuse to the battery.
The fan ground to pin 30 or 87.
The unused pin 30 or 87 to a chassis ground.

Depending on how your thermo switch works, whether it sends a ground or a voltage signal will determine how you wire pins 85 and 86.

If it sends a ground signal, wire that to either pin 85 or 86, unless its a relay with a diode - follow the manufacturers directions for that.
The unused pin 85 or 86 goes to either a constant or switched voltage source.

If the switch sends a voltage out, then that goes to 85 or 86.
The unused pin goes to chassis ground.

If you have A/C, that's going to change how you wire things too. You have to pay attention, because the A/C switch and the thermo switch can send out different signals. A 2g A/C switch sends out voltage, but the ECU sends out a ground for the Thermo signal.

Even though there are many different ways to safely wire a relay, you should come up with a standard that suits you. This way if you add more relays for other things, you never have to guess which pin is which. For instance, I always use this:
pin 85 = coil -
pin 86 = coil +
pin 30 = ground or voltage source depending on application
pin 87 and/or 87a = item being powered or grounded