I have a newbie question.

I am putting both radiator fans on a switch that will be wired inside the car to a switch. I was told by someone that these should go through the fuse panel.

How would I wire this up?

I have a wire coming off each fan into the car - but I need a wire that always has power coming from the fuse panel as well (I was told a 25 amp fuse would do).

Thanks!

 

There are many ways this can be done.
This is the method I've used (and still use). I'll start from scratch so if you've already built a part of this, excuse me.
You can't (or shouldn't ) run the fans DIRECTLY through a switch. They draw a lot of current and the potential for melting down your interior switch is pretty good. The OEM and the aftermarket use a relay to provide switched power to the fans. If you don't have a relay they're found in abundance at the scrap yard or better still you can pick one up at the local parts store (it'll have a wiring diagram too which will probably be helpful).
So that said, the method would be as follows:
In the fuse block there will be taps for ignition (key on) and for full time (always on)power. From the full time power tap, plug in an in line fuse holder rated for 30 amps. From this fuse, run a 10 gauge wire to one of the relay (load) terminals. From the other relay load terminal , go directly to the positive (+) wire/terminal on the fan(s). The other fan wire (-), should go to a solid ground.
That takes care of the power circuit.
The relay will have another pair of terminals made for switching. From another 12 volt source (usually a switched/ignition on), go directly to your interior mounted switch. From this switch run a wire to one of the two remaining terminals of the relay. From the last remaining terminal, you should go to the coolant temp switch mounted in the cylinder head. The temp switch will close when the coolant is hot and connect the relay circuit to ground.
When this happens, the relay is energized and the power circuit to the fans is complete.
It might sound complicated but it really isn't that difficult.
I'm sure others will chip in with their methods. I use a variant of this setup. My fan relay is mounted near the battery as is my in-line fuse holder. I have an interior switch that allows me to select whether I want the fans to run even when the ignition is off. (Very useful when at the drag strip and I want to cool the engine down a little).
Hope this helps.

The terminal numbers in the diagram may not match the particular relay you get. The wiring method is the same. In the diagram, the circuit is as I have it (more or less) in my car which allows for automatic operation through the temp switch or manual operation via the toggle (I don't use an indicator light).

 

Thank you so much for the detailed description. I am starting from scratch so that all helped.

I have my relay now, I am reusing the MAF relay I ripped out earlier. Now, there are two thin wires, I take it one is for the temp sensor in the side of the heads, and the other is going to my switch. The temp sensor I have is in the side of the head is the stock one, with 1 wire coming from it to the relay - is that correct? It should close the relay once up to the right temp?

The back of the fuse panel - this is where I am so new to all this it hurts. So, I will put in a 30 amp fuse into an open spot - but how do I know if it has full time power - is that written somewhere? And does one of the the fat wires on the relay go to the back if the fuse panel and connect to the one side of the fuse? Then the other side of the fuse goes to my switch?

The relay I am using was from mass air flow relay. There is a big orange wire and a big tan/white. Does it matter which one goes to the fuse block and which one goes to the fans?

Thanks for the help.

 

Your MAF relay has two thin wires and two thick wires and you use them as you describe. The thick orange goes to an open spot on the fuse block (although it really doesn't matter which wire you choose). The fuse block is labelled but a little hard to decipher. A test light is useful. Connect one end of the light to a good ground and poke the other end into the open slot. If it lights up with the ignition off, you have full time power. If it only lights up with the ignition on, then that's switched power. If it doesn't light up at all, try another slot (or your test light connections). The wire you push into the fuse block should be fused (10 gauge wire/30 amp fuse). The other thick wire on the relay goes to the fan.
Don't forget the ground wire for the fans. Also 10 gauge.
The two thin wires are for the fan control. You need another source of power to run the relay. In a pinch you can use the same power for the fan although I would recommend finding another open spot in the fuse block. It does get a little crowded. The relay control wires take very little power (less than an amp) so it's possible to share with the something else like a radio of some other accessory. So, from the power source, in and out of the relay, through your switch and then onto the temp sensor. Switch on (closed), temp switch hot (also closed) and the relay is energized and the fans should come on.
If you use only full time power for both the fans and the relay, then the fans will continue to run with the ignition off and shut off when the temp switch gets cool enough (or your turn off the switch). That's a little tough on car batteries (I've done it). If you use switched power for either of the two items, then the fans will only work with the ignition on.
The only thing I can't qualify is whether you MAF relay is suitable for the application. If it doesn't the power capacity that the fans require, you'll burn it up soon enough.

 

How do you put a wire into the back of the fuse block? Does it go into the back, or would I plug the wire right into the front of it?

So, just so I have this straight. I have the red wire from the fan that connects to a big relay wire. The other big relay wire will have a fuse in it before I plug it into the fuse block?

 

I was thinking about that after I posted. The wire goes in the front of the fuse block. There are special connectors you can get from Pico (and others) that plug directly into open sockets on the front of the fuse block however, what I've done in the past is to use a male spade terminal (of the appropriate size) that's crimped onto the wire. The spade will push right into the open slot in the fuse block.

Yes, you have the wiring correct. Fuse block (using a spade as described above) to in-line fuse to relay. Relay to fan.

 

good info

 

Is far easier to run the fan supply ( using same inline fuse ) ,
direct from the Pos terminal on the battery or the starter
(were the factory gets it's heavy load power supplies from ) .

 

sorry for bringing up this old topic but it is a good write up!
My question is, "is this for a single fan?"
Or if we plan on running two fans, will we need 2 relays? and will 30 amp fuse be enough along with the 10 gauge wire for both fans?
Thanks

 

Don't really need a relay for coolant fan if you get the right parts. A 30a rated toggle switch with a 20a fuse behind is isn't going to melt the switch. (I went 20a fuse because my single fan only draws about 11a, not sure for a dual fan)

Though depending on where you wanted to put the relay it could benefit from have a shorter distance for the power to travel. Like, have the relay in the engine bay right by the fan itself.

 

Yes, 2 fans 2 relays, 30a for each fan, I'd use 12ga wire and mount the relays near the fans by the core support.

As to the trigger for the realys, really it should be run with the ignition hot to one side of the coil, then the other side you run to a switched ground, preferribly with a fan temp switch triggering them, and then T that wire to go to your switch to allow you to turn them on when you want also.

 

Ok but i also read somewhere (cant find the link) that both fans only run when the A/C is on, only one fan runs under normal driving.
Is that true or did i misread?
I do not have A/C in the Car so if i can just run 1 fan or convert to one fan that would be nice.

 

Yes, the primary fan is used by the ECM to cool the engine.
The secondary fan kicks in if the engine get close to overheating.

If the A/C is on, both fans run.

If you wish to run just one fan, pick either. Just use a switch to ground the appropriate fan relay. It is much smarter than running 20+ amps through the passenger compartment.

Hope this helps.
Lou

 

Thank you sir!
I will be tackling this today.
Thanks again for everybodys help

 

Why is it that you want to run just 1 fan ?

 

Yeah i just finished and thought that myself. Lol
I hooked both of the up. Might as well right?
Thanks

 

This was a great post to come upon. Having a coolant temp switch problem, (can't get it out, technicians even couldn't), and wanted to hardwire a switch to the fan motor. Thanks for the info. Great question, great info.

 

If you absolutely, positively cannot get the switch out of the head, you still shouldnt need much if any at all of this thread, wiring the single wire going to the temp switch to a switch that is switched to ground will provide operation of the fan through the stock relay.

Though if by some miracle I absolutely couldnt get something like that removed, there are several other locations you could install a temp switch, rather than risking forgetting to turn your fan on.

 

I have spare temp switches if you would like to use a replacement switch for your fan. It mounts to a surface so you can bolt it to a head or intake. Let me know if you'd like one.

Lou

 

Good point. I was just thinking of wiring it to the dash instead of another location. I do have a replacement coolant temp switch. The one that is located between cylinders 6 and 8 on the underside of the motor. Thanks for the advice though. That does sound easier.

 

Piece of advice: find a better mechanic.
A good mechanic will easily break the stuck switch off, drill and tap the hole out and install a new switch. Been there, done that, it's not that hard.

 

I definitely need to do that. I had just moved to the area so I am still looking for someone decent. I am stubborn in the way that I want to do everything myself. But with this one I may just have to. Especially with being in Arizona.

 

The one on the passenger side with the a/c box in the way shouldnt be quite that easy. I'd think you'd at least need a right angle drill, if not having to remove the evaporator blower box.

 

Yea. And unfortunately I don't have those tools. But I do have some time to take care of it. Thanks for the advice and help though!

 

You are right, good tools help. If you don't have those, it's not easy to do at home. Sorry, I was looking at it from my angle where I have a lot of tools (collected over the years) and thus I view many non-trivial repairs as easy tasks.

When looking for a new mechanic, feel free to ask if they have a right-angle drill attachment and NPT taps to chase the threads after drilling out the old sensor. That will give you a good idea who is capable of completing your task.

Good luck with the hunt.
Lou

 

Oh no need to apologize. I completely agree that it is something easy to do at home if having the right tools. Otherwise I would have done the same thing already. I am slowly starting to build my own collection, but school now a days is expensive. I will ask specifics when I go to look for mechanics. Didn't think about that. Thanks again for all the help.

Jake