[Malibu1980]

lol, allmost.......in was just under my car tightin my tranny lines because it leaked a little bit, and i went to start my up to see if they leaked, so i started it up and was looking under the car, all a sudden a smell smoke, so i look up and there is alot of smoke commin from under the hook and inside the cab, so i turn off the car and pop the hook and i see that the wire going from my battery to my switch for my electric fan is smoking, so i disconnect the battery terminal, and the wire is all shot to hell.......what do u think caused this.............I have a wire going from my battery to my toggle switch, then on the otherside of the switch a wire goes to my electric fan, then the otherwire from the electric fan goes to my negative side of the battery.......whats wrong??

[Gardenfan]

You have either a dead short, which can happen in any number of places, even inside the fan motor. OR the wire you are running is not rated for the load of the motor. You might have to step up to a larger gauge wire.

PS, always keep a fire extinguisher in your car!

[4 Jaw Chuck]

Ever heard of a relay?

[dmorris1200]

Originally posted by 4 Jaw Chuck
Ever heard of a relay?

Too funny!

[60convert]

you will want to wire in a realay and make all your wires so they go through a fuse.
Jesse

[camaroman7d]

I try to tell guys about this all the time. Whenever you have an electric motor (ie.. fuel pump, water pump, electric fan, etc..) you MUST use a relay and a fuse. If not you are asking for a fire, just be glad it happened when and where it did. If you were cruising down the highway you could have lost your car.

Anytime you are powering anything that draws moderate to heavy current, you need a relay (fog lights and other things of that nature as well).

Royce

[87442lover]

You dont connect the electric motor straight to the battery! LOL! Omg I'm surprised you did'nt have a fire sooner. If anything you can jerry rig it into the fuse box on a 5amp fuse or something.

[Malibu1980]

Originally posted by camaroman7d
I try to tell guys about this all the time. Whenever you have an electric motor (ie.. fuel pump, water pump, electric fan, etc..) you MUST use a relay and a fuse. If not you are asking for a fire, just be glad it happened when and where it did. If you were cruising down the highway you could have lost your car.

Anytime you are powering anything that draws moderate to heavy current, you need a relay (fog lights and other things of that nature as well).

Royce

WHen u say fuse do u mean an In-line fuse???? and i relay? whats that, im not really knowledgable with electric wireing, which prob is why my car allmost cought onfire

[camaroman7d]

Here is a diagram of how you should wire a realy. You can pick up a realy at any auto store or even Radio Shack.

With an electric fan you will typically want to run a 30amp fuse.


Royce

[dmorris1200]

What that picture doesn't show is the way a relay works. The whole point of the relay is to allow a small amount of current to control a large current devise. You can see in the schematic I drew that the high side current uses a short path of flow from the battery, to a fuse/fusable link, to the relay, to the fan, to ground with large diameter wire. The switching side of the relay uses very little current which is safer for longer wire runs of smaller gauge to make it to a switch inside the car of whatever else you may want. Both sides of the system should be fuse protected.

[wld bil]

A relay is basically an electrically powered switch. It is designed to carry the large amperage that things such as fan motors require. Most toggle switches are not designed to handle this load. I have seen many "shadetrees" install foglights etc. running the power through just the switch. It is asking for trouble, as you found out. The relay carries the load for the devise, the toggle activates the relay. Example fog lights, you want them to work only when the headlights are on, but want to control them with a toggle. Find the hot wire that is activated by the headlight switch, run a lead wire (with a fuse) from your headlight switch hot wire, through your toggle, to your relay. The toggle will activate and deactivate your relay, not your lights. The relay will control your lights. It's a chain reaction. The reason for the relay is to carry the heavy load that the toggle is NOT designed for. You relay is wired to a battery source and grounded just as a switch would be. Pick up a relay and look at it, most have a schematic on them. They are easy to wire once you understand what their purpose is and how they work. In your case, the wire running through your toggle will be a SWITCHED hot, one that is only hot when the ignition is on. You do not want to turn you car off and forget to turn off your fan. There are many ways to wire an electric fan. A switched wire to the fan RELAY, the fan will run whenever the ignition is on, not very conducive to long fan motor life. A toggle ran between the fan RELAY and a switched source, you control when the fan is on; want to forget to turn it on and overheat your engine? Or a temp sensor, the temp sensor will activate the fan RELAY, which will tell the fan to come on. In summery, relays are wired to their own 12v power source to run what ever item they are controlling, toggles turn on and off your relay. Hope I haven't confused you.

[Malibu1980]

okokok, My Switch never had a Ground on it, becuase there was not a place for it, it only had 2 places, Battery+ and Accessories..........Can i just run a wire from the fusebox to my switch then to my electric Fan???? will that fix the problem?

[60convert]

well now at leasat you have the fuse in line but you missed the whole part of the relay being able to take lots of amps as to a toggle switch only taking a few. And the more amps and the longer the wire the bigger you need it to be.
EITHER RUN RELAYS OR CARRY A FIRE EXTINGUSHER...
Jesse

[camaroman7d]

The whole purpose for a realy is so you don't have to run the higher amps throught the switch (or over long distances). This was explained above.

You are going to have a very hard time finding a switch that will live with a ~30amp draw. Meaning the switch is going to fail (short, melt, arc, etc..), you will still have a fire hazzard even with the fuse. You can have a fire with much less than 30amps (this is the size fuse you will need to power the fan). You really need to run a relay, while the hand draw picture above shows (basically) how a relay works, it can confuse someone not familiar with relays/electrical/electronics this is why I like to use the simple picture. Doesn't really matter how it works just wire it correctly and let it work.

Think of the relay as a remote switch for your fan. This will keep the high amps out of your interior where there are lots of things to burn.

All these guys wouldn't steer you wrong, learn from others mistakes.

Royce

[horvath]

Listen to all the good advice you're getting -- installing a relay is a must for an electric fan. When those babies kick on they punch a LOT of juice and NOTE:

Do NOT use an in-line fuse! -- Use a fusible link.

An in-line fuse will surely fail after a short time, every time. A fusible link is the best way to go ... if you're running a 12 gauge wire, you'll want a 16 gauge fusible link. You can buy them HERE

If you want a good relay kit, you can buy the best HERE

And if you want to talk to the guy who sells the above ... he's a wonderful guy and patiently answers all questions ... you can call him, he'll straighten you out on all the why's and how-to's and you can order what you want on the spot:
Mark Hamilton: 559-539-7128

I'm doing a whole project on rewiring my engine area: electric fan with two relays, headlights with relays, alternator and two terminal blocks on my firewall, delivering full voltage to everything, including my fuse box under the dash.

I'm about halfway through the project and already I can see a big difference -- my electric fan use to ping my voltage gauge every time it turned on; now I can't even see the gauge move when it turns on!

I'm posting a photo-tutorial of the whole project at my site:
Mad Electrical Improvements

Alan
54 Chevy Pickup