Technical wiring a pusher fan

I am installing a small (10 in) pusher fan. My problem is I am not 100% sure how to wire it. I want to have a simple toggle switch to turn it on and off in heavy traffic, from the dash. I think I should use a relay but what wires go where and how do I wire it to the switch and do I wire the switch to the fuse box, or where. And what gauge wire should be used. If anyone can help, it would be greatly appreciated.

 

Buy a relay (summit racing has them) and follow the instructions, you will be using the switch in place of the tem sensor is all.

I don't know what color the wires coming out of the fan are but it is a DC motor so just get jump wires and jump it to your battery, if it is turning the wrong direction switch the wires.

 

Somewhere on the fan should be some electrical info; volts (12V I hope!), amps or maybe watts. If it's watts, divide by 12 to get amps. Wire size? #14 is good to 12 amps, #12 to 16 amps, and #10 to 24 amps. Fuse to match the wire. You may or may not need a relay; if the switch you have is rated at 150% of the motor amps (and again, this should be on the switch if it's a quality bit) no relay is needed. Come from the fuse box to the switch, switch to fan. Ground the other fan wire.

 

Oye !!!
No pusher fan

 

As stated the fan is small (10 in.), it's 12 volts, and draws only 5.4 amps (according to the box). The toggle switch says 20 amps. Does that give you anymore information as to what I have to do to wire this thing.

 

so, why installing a pusher fan? what are you putting it on? need pics

 

Just installed a new crate motor (stock 350 Chevy) and new aluminum rad. Runs fine at highway speeds but starts to get warm in slow traffic. Don't have room for large pusher or puller fans, so I thought a small (10 inch) pusher fan that I can turn on or off as needed, would help.

 

Pusher fans restrict airflow.

 

OK - not first post on the heating problem - what have you done in response to other input/suggestions?
no improvement yet? so, no heat problems with old engine. what kind of horsepower? running a fan shroud - all gaps around radiator/grill surround sealed for air to only go through radiator? what pressure radiator cap? using recovery tank? sure gauge is working properly - mechanical/electric-where is sender mounted? automatic trans/where is trans cooler mounted? what mixture of coolant running?

 

My fan goes direct to a toggle switch, then to the fuse box with 14 wire. Don't spend a bunch of time on it until you know it helps.

 

Some improvement, 180 degrees on highway, horsepower, probably around 250, new aluminum radiator, sits almost inside the grille shell, good air going in. Pressure cap 17 lbs., overflow tank, yes. Temp gauge working properly, mechanical, sender unit installed in front of intake manifold close to thermostat housing. Trans cooler is mounted just below radiator inside the grille shell. running a 50/50 mix with distilled water. Like I said, highway no problem, heavy traffic it can go to 230, I just haven't stayed in heavy traffic to see how much hotter it would get. Running mechanical fan off motor, no room for a shroud. Some local guys said they all run a pusher fan with a switch and turn it on or off as needed.

 

I probably won't know if it works unless I try it.

 

Yep, that's enough. Use #14 wire with a 15 amp fuse, no relay just the switch, and you'll be good to go. You want the larger fuse because electric motors have 'inrush current' when starting; this can be up to 1200% of running current, but lasts only a fraction of a second. The larger fuse will prevent nuisance tripping while still protecting the wiring.

I'll leave it to others to debate the merits of electric fan types.... LOL

 

Can I use a wire coming from the fuse box to "tap into" or do I have to find a empty fuse connection. Also, the way I understand your reply, I will need a 15 amp fuse on the wire from the switch to the fuse and to the fan itself, is that correct?

 

You could wire the positive to the accessory post on the ignition switch. You definitely want it switched and the ignition switch is well-protected without adding another fuse. I would run a relay too.

 

It would be much preferred if you can find an unused fuse space, and install a 15 amp fuse. Tapping into an existing wire is very iffy unless you know what it's for and know that it has adequate capacity for the extra load. The circuit should be power to fuse, fuse to switch, switch to fan. Don't forget to ground the second wire at the fan to metal.

All a relay is is an electrically-operated switch, and if the switch you have is rated for the load, the relay is just another failure point.

 

If there is room for a fan, there is room for a shroud.

 

I have an old Ron Francis wiring kit (one of his first generation kits) all the wires coming from the fuse box are listed. One is listed as "battery" could that one be "tapped", or is that still iffy?

 

If that wire is connected to one side of an unused fuse space and the other side of the fuse space is hot when the key is on, that'll work. Use a volt/ohmmeter to verify that's what you have.

 

I wish there were a double like button.

Maybe its a mini fan and needs a water pump riser and a full size fan blade. Of course I have no way of knowing this. Just a wag and a poke at another thread

 

+1

 

I was able to get a good look at the fuse box and there is a connection point for a fan, however it calls for a 20 amp fuse. Can I use that connection and a 20 amp fuse, or would a 20 be "too big". As you can tell I am not electrically gifted.

 

A 20 amp fuse is too small for an electric fan. On start up the initial amperage draw would exceed 20 amps. I had a Ron Francis wiring kit with a 30 amp fuse that would pop on fan start up.

 

Electric motors draw alot more current when starting, but just for the moment before they have reached normal operating rpm. Fuses will also tolerate current well over their rated current for a short moment (it takes time for heat to build up and melt the fuse wire). With a small low power fan I wouldn't expect any problems.

But I'm also curious about how it looks if there isn't any room for a shroud. As someone said, if there's room for the fan a shroud should fit there too.

 

Believe me, I would be the first to put a shroud on if I could. The engine sits way forward on this car, the current mechanical fan sits about 1/2 in. from the radiator. Even the guy that built the radiator agreed that there was no room for a shroud.

 

there is a tech article here somewhere. That details how to make a shroud with fiberglass. I just made one for my 51 fleetline using that idea.
-Pat

 

How about a pic or two of what you have going on Bob?, the radiator in my '57 is about 1/2 from the fan as well, I made a two piece shroud for it...I think we're just trying to see why it won't work for you?

 

TECH: Custom fit fan shroud. | The H.A.M.B. Ah Haa, <--- there it is.

 

Depends on the size of the fan.... In this case, with a mere 5.4 amp running draw, a 15 amp fuse is 280% of the running current. Generally, going 250-300% over is more than enough on small motors like this. I strongly suspect that a 10 amp would do it....