TX-SleeperC5

iTrader: (2)

Looks like I need a little help on how to wire a dual OEM fan set-up to a single switch inside the car or to 2 switches.

A little help would be greatly appricated.

Keoman

iTrader: (3)

Question, why do you want a switch in the car?

Midas posted this useful picture, it applies to dual fans the same, just follow the diagram for each individual fan.
Adding a relay for AC is not too hard after everything is done also.

Note, the diagram uses a fan switch in the block to control the fans. If you want a switch in the car, run the wire inside to a switch instead of hooking it to the fan switch in the block.

TX-SleeperC5

iTrader: (2)

I'd prefer a switch because the relays are failure waiting to happen !

And per the diagram above... I'll need 2 relays, one for each fan....

redneckjoe

i've got both my fans hooked up to a toggle switch.
i used 10 gauge wire and a 30 amp fuse.
black to ground, red to switch and battery.
havent had any problems.
just got to remember to turn the switch off.
get a good 30 amp toggle switch, not a cheap one.

Joe Tag

iTrader: (4)

Ugh, the lesser of two evils here. The relay is a failure waiting to happen, at some point in the very distant future. The switch without one is a fire waiting to happen. Choose wisely.

TX-SleeperC5

iTrader: (2)

Without one what ???

And a fire only comes from too small a wire.

TX-SleeperC5

iTrader: (2)

30 amp fuse for each fan ?
OR a 30 amp fuse for both ?

heat seeker

iTrader: (5)

You need to use relays not just a switch. When installed with the right wire size, and the proper rated fuse, it works flawless.

I have my factory dual-fans custom wired with one switch on the dash. I used one factory oval relay, and used one 25A fuse. My relays and fuses are under my passenger dash, my wiring is routed away from the engine (less heat), and I used a larger wire size than factory. No problems here.

Joe Tag

iTrader: (4)

Without a relay. It was a followup to the previous sentence, try and follow along. Distance is resistance in wiring. You can have 3 feet of wiring with a relay right next to the battery, or around 20 feet running from battery to switch back to the fan. Restorob was popping 40 amp fuses because his fan was wore out with a relay and proper factory wiring. Add the resistance of 20 feet of wiring and you have way overloaded that 30A switch. I've said my peace and can just drive my car with no worries of switches.

TX-SleeperC5

iTrader: (2)

thanks for your input.....

TX-SleeperC5

iTrader: (2)

Sent you a PM...

Bigfoottpi11

You only need the passenger side fan connected to a toggle switch and you dont need a fuse or a relay either.

Joe Tag

iTrader: (4)

Oh dear god. The advice keeps getting worse. I guess they're just another one of those things GM had engineers design that can be deleted with no consequences. You MUST know better than them.

redneckjoe

i use a 30 amp spade fuse for both fans. just used 2 female spade connecters in-line to hook the fuse up. i do have a battery cut off switch in my car if ever needed.

to each they're own. relays suk IMO. i've been 12 volt wiring boats for 20 years without a fire. kinda think i know what i'm doing. radar, GPS, lights, etc.,...all snaked through aluminum pipe/towers/etc.

use the correct size wire, 10 gauge, and a 30 amp fuse, and a 30 amp switch, cover the wire correctly, and dont lay it on the exhaust, no problem.

yea, car engineers are so much more smarter than they were years ago. most modern cars are throw-aways after 10 years with electronic problems. total BS, IMO. i'd rather have an older car then a newer POS any day, for reliabilty and cost of maintence. but yea, fuse have been around for a long time and still in use.

heat seeker

iTrader: (5)

Here's how I wired my fans....

I took out the fan relays completely, relocated them, so I could wire them to a switch in my dash. I figured, why buy new ones when I have perfectly good ones. Remember, I didn't want the fans controlled by the ECM or a temp switch in the block. This is for complete manual control.

If you choose to use the OEM relays, you may have to use a small screw driver to re-arrange the location of the wires, or order a relay harness on ebay. Just make sure the larger #12 gauge wires are in the same orientation. You can use a square relay from the auto parts, that's up to you. They have a diagram on the package.

So first, I cut and connected my two (-) negative fan wires together and ran them to a chassis ground. Then I took the two (+) positive wires and connected them together to a #10g wire......to run to one side of my 25A fuse.

A - #10g Orange wire, goes thru a 30A fuse, then to the (+) wires on the fans.
F - #18g Tan wire, goes to the chassis ground.
E - #10g Black wire goes to your battery.
D - #18g Green wire, trigger, goes to one end of my toggle switch in dash. The other end of the toggle switch goes to a 12v ignitions source.

You can't see in the pic, but I actually up-sized the orange and black wires to a #10g, then to the (+) positive wires on my two fans. Just to play it safe.

Here's what I ended up with. Relays and a fuse block, hidden in the dash compartment. Simple and clean.

Joe Tag

iTrader: (4)

Quite a convoluted way to do it. If you are dead set on running a switch, all you need is a standard toggle, run one leg to a ground and the other to the green and white wire on the relay. Flip it on and the fan is on. You can even leave the ECM and temp sensor hooked up in case you forget to flip the switch. But what do I know.

formula1LE

iTrader: (3)

Wow.....that's all I can say.

formula1LE

iTrader: (3)

I'm going to add a favorite phrase of mine to my SIG. line....

heat seeker

iTrader: (5)

Not really. My wiring harness has been re-done, so they're are no visible wires in the engine bay. Yes, he can wire it exactly how you describe it.

However, he pm'd me to know exactly how I did it.....I told him.

formula1LE

iTrader: (3)

Heat seeker....though I don't doubt your setup works, what happens when your switch gets hot since it is carrying a load? I would rather a high current relay handle an amp load vs. a high resistance switch-regardless of its amp rating. And, switches are not designed (relays are hence the built-in resistor) to handle large voltage spikes either. And then there's always the chance you forget to turn the fan(s) on. Relays are far more reliable than any switch-heres a fact....relays are rated in numbers of switching cycles. Typical OEM relays are rated at 125,000-150,000 cycles and high quality (TYCO) relays are rated at 250,000 cycles. No manual switch has that kind of durability.
Hopefully you keep a fire extinguisher handy.

heat seeker

iTrader: (5)

There's no heavy load going thru my switch, so they don't get hot. It just toggles the relay on/off. The load runs thru the relays #10 wires, switch is just the trigger for the relay to activate.

What would be the point of the relays, if I'm running the load thru my switch? Here's an ad for a connector that explains my exact harness wiring...... http://www.ebay.com/itm/EFI-Connection-Electric-Fan-Relay-Pigtail-TPI-GM-/141367476468?pt=Motors_Car_Truck_Parts_Accessories&hash=item20ea2880f4&vxp=mtr

formula1LE

iTrader: (3)

Ah....I see how you came up with it. So basically you just don't trust a factory style temp switch then-nothing to do with relays then. I guess if you don't mind flipping a switch all the time....I just like an automated cooling system a providing it performs as designed.

heat seeker

iTrader: (5)

Ahhh, sarcasm...I gotcha. The OEM cooling system was not designed for my current setup.

1. I run my car at the track. I can manually run my fans and electric water pump, in the staging lanes to cool my engine between passes.

2. I run a 500 + hp 383, in 103 degree temps in TX....um yeah, the factory cooling system from the 1980's is gonna take care of me right?

3. Apparently my setup works, because my car runs at 170-180 degrees, which is exactly where I want it, while other guys complain constantly about over heating problems.

Seriously.

TX-SleeperC5

iTrader: (2)

Well I just replaced a bad radiator and one non-functioning cooling fan, ran the car for around 45 minutes and neither one of the fans are running.

Not sure what the problem is now but I'd rather just hook them up to a switch and be done with it.

formula1LE

iTrader: (3)

No no....if a switch works for ya cool-I just wouldn't want to forget to turn em on. For a street car obviously more of an issue. And yes I agree the stock type fans suck (and no PUN here....) so I'd always recommend a newer style setup but now you're getting into more powerful fans and switches aren't a good idea with HO fans with 30A relays IMO.

TX-SleeperC5

iTrader: (2)

I saw this on another search I did.... I tried that already and nothing happened.
Wired it JUST like this, turned on the car, flipped the switch and NOTHING !

So as of tomorrow, fuse link on power wires to fans, ground each fan, wire fans to switch (load side of switch)and run power to switch from power source.... VIOLA !! both fans will run when switch is thrown ! NO MORE relay and temp sensor problems !!

Joe Tag

iTrader: (4)

....

TX-SleeperC5

iTrader: (2)

That pigtail doesn't match my OEM relay..... I'd have to get a different relay.

Joe Tag

iTrader: (4)

....

Joe Tag

iTrader: (4)

....

Joe Tag

iTrader: (4)

....

TX-SleeperC5

iTrader: (2)

Okay... then why are both fans routed through this OEM relay ?

And I'll check the fuse center tomorrow to see if indeed that may be the case...

Joe Tag

iTrader: (4)

....

Joe Tag

iTrader: (4)

....

TX-SleeperC5

iTrader: (2)

The GTA is all original. I have changed nothing on it. The fan harness is plugged into a main harness but only has one relay for both fans.... I know this because I removed to check it out...

I'll take a look for the fuse in the battery area as well.....

Joe Tag

iTrader: (4)

You have no intention of putting another relay in do you? You have replaced a radiator, fans and an engine with a cracked block but a $15 relay is just beyond any realm of comprehension for you? I will wish you luck and move on.

heat seeker

iTrader: (5)

Remember, you do need to run a relay, if not your switch will melt/fail, do to not being rated properly and excessive heat. Follow the wires from the positive on your fans and you'll know exactly how they're controlled and if there are two relays or not.

If your fan pigtail doesn't match what I showed you, it's because I used a small screwdriver to pull out the pins, and relocated the wires in the connector to my preference. That's why I mentioned you can get a square relay from Autozone and it will work the same. You just need the larger wires in proper orientation, seeing they carry the load.

TX-SleeperC5

iTrader: (2)

Okay so this morning I checked fuse box and found a blown fuse... ALSO, found a bad wire serving the charging system. Fixed al that.

Now back to the fans. Hopefully the blown fuse will fix that problem. If not, here's my question...

Can I use the OEM relay with direct power from the battery to run the fans if I unplug it from the rest of the harness ?

As for Joe Tag, I asked a simple question.... Why are both fans tied to ONE OEM relay ?
If I have to buy 2 relays and wire each fan separate, so be it. I just need to fix this. I'm tired of the car overheating and being unreliable.

Joe Tag

iTrader: (4)

We'll go with the premise that it's not you, it's me. I have little patience for answering questions that have been answered many times for you, even with wiring diagrams to show you what you are being told. So instead of answering questions, I will ask them. Answer them and you can answer your own questions.
Were you the only owner of this car in it's 27 year history?
Do you know what has or has not been changed in this time by the previous owners?
Is it possible someone else has put a single fan harness in place of a dual fan harness and added another pigtail for the second fan, be it factory or not?
Is it possible someone has changed a single fan for a dual without putting a dual fan harness in?
Are these the type of things that are frequently done by people who do not know any better?
Have you been told and shown with pictures that GM did not use one relay to control two fans on these cars and their functions described for you?
How well has a harness with a single relay controlling two fans worked out for you so far?
What happens if the wire from the battery to the relay or relay to the fan is overloaded or short circuited and there is no fuse to protect it?
Is this something you would like to happen to this car?

TX-SleeperC5

iTrader: (2)

You know....
I think its best you move on.....

I started out asking a simple question for some help and what do I get.... "chastised" by you for wanting to omit the temp sensors and relay(s) on which they operated.

ALL is want to direct wire the fans to a switch, If it's better to go through a relay or relays, so be it !!

TX-SleeperC5

iTrader: (2)

Thanks for you help !

Joe Tag

iTrader: (4)

I will move on but I will point out a timeline for you so you can understand what really happened here.
You got the correct answer in the first post. It wasn't what you wanted to hear.
Then you answered all you needed to know yourself in the next post. But..There was this horrible relay you had to buy.
Because you didn't bother to check the fuse, you got frustrated.
You couldn't possibly fathom the idea that someone else may have changed something in 27 years before you.
My questions were legit to help you answer your problem.

willexoIX

Not taking sides but Joe is right. If you directly power the fans through a switch then there is a very very good chance you will cook something and it might just be the car. Ask me how I know. I wired a single fan to a switch, only to have my hood start billowing smoke at 80mph on the freeway. I couldnt see out of the windshield. I also failed to fuse it properly.

You want 1 relay to each fan. If you want them both on one switch, tie both ground triggers for the relays together and to the switch. You can also wire the two 12v relay powers (not the main feeds for the fans) together to a fused switched power source. Then wire your fan ground to ground using appropriately gauged wire, and run your fan 12v using the same gauge wire from the battery, to the relays and from the relays to your fans.

Question answered. This is the only way to do it, albeit in a couple different ways with relays, without risking the safety of the drivers and passengers of the vehicle. And if you forget to turn the switch off, turning the key off will kill the fans.

But hey, its your car.

TX-SleeperC5

iTrader: (2)

Well there you have it.... another nice simple and useful answer to my question !!

Thank you VERY much !!

heat seeker

iTrader: (5)

I agree with both of you. I directly switched my fans with no fuse, or relay about 10 yrs ago, when I didn't take the time to understand wiring. I melted several switches. Not smart at all......I could have easily started a fire.

Oh the dumb things we do when we're in our 20's.... lol

Here's a diagram (standard square relays). For anyone reading this thread, it doesn't get an easier than this. If your fans draw more current than one relay is rated, use two relays. Just control them with one switch.

TX-SleeperC5

iTrader: (2)

And there you have it.... another good answer....

redneckjoe

more ways than one to skin a cat!
this site is a good melting pot for info.
glad to see everybody being mellow.


get your fans working how you want them?

TX-SleeperC5

iTrader: (2)

formula1LE

iTrader: (3)

Ok.....if you have room to install a 6" deep single fan, here is an option I run-its a complete stand alone setup wiring as a 3-speed fan and has 6 connections. This uses 2 GM style temp switches and is as automatic as you can get-with the added benefit of 3 speeds to boot. This setup (harness-wise) can be used to convert any fan(s) to operate in 3-speed mode but depending on how much you want to babysit your electric fan, this is just an option.

For the record, this fan is 18" in diameter, measures 24x19x6 inches and on high speed moves about 4500-5000 CFM. I use it as an alternative to the Lincoln Mark VIII fans.

58mark

iTrader: (3)

Good thread. maybe you cn give me some help related to it

I'm considering doing a LS1 fan swap on my 86 trans am. I'd like to leave one fan wired the same as the single fan on my car. From what I understand the single LS fan with the shroud will do a better job than the stock fan on my car, but I also want a second fan that can be used for harsh temperature days, like days 100 degrees or above.

Here's my options.. Let me know what you think.

I know you aren't going to like this first one, but it's simple. Run a 12 gauge wire from the battery and a 30A fuse directly to the second fan, and have the ground controlled by a switch on my dash (i'm going to try to repurpose my subwoofer switch)

second option. Run a relay so the second fan come on when the car is above 220 degrees. i know this is the better way, but here's my question (sorry if they are dumb questions)
Does my 86 305 have the spot in the head to put a thermal switch? If it's not there or is already being used, what do I use to trigger the relay?

right now it looks like my single fan runs all the time, even when the car is cold. Does that mean the thermal switch or the relay has been bypassed?

I don't mind doing it the right way, I just need an education on how to get it done