How to wire fans
 

Ok. I have a 1990 Full size Bronco. The ac doesn't work good and takes too much gas to run anyway. I bought 3 little 6" fans that plug into the cig. lighter (I will cut off the cig lighter plug) to mount on the inside roof to blow on my three little kids when stopped in traffic. I want to get straight power not switched so the fans can be turned on when the key is off. I plan to mount a switch on the dashboard so I need to figure out how to wire everything. I had planned on running a wire striaght from the battery with an inline fuse to a new fuse block (mounted under the dash) and the ground wire will go to the same ground as the oem fuse block. From the new fuse block (running a 30amp fuse) to the switch mounted on the dash, and from the switch to the fans. All three of the fans power wire will be crimped into on connector to connect to the switch as well as the ground wires. Does this sound right or am I looking for trouble?

Thanks for any help I can get
solidpvc.

It sounds ok, as long as you know the amp draw of the three fans together. If it's close to 30 amps, run at least a 12 guage wire and a 10 guage would not hurt.

I would not worry about the ground. You can run a short ground wire from each fan and bolt it to the mounting bolt that will hang the fan. I am assuming you will be screwing into the metal structure of the roof.

You need to be careful too, and get a switch heavy enough to handle the load. Make sure it's rated for DC use.

I'm running 10 gauge for the power wire to the fuse block, from the block to the switch. I'm not sure what gauge the wire is going to the fan, maybe 16 guage (I'm not next to the wire but can update tomorrow with the wire gauge. The original wire on the fans are really small. The wire i'm using is bigger than the orginal wire so that should be ok. Someone told me to run a relay between the switch and the fans to protect the switch. Should I do this or will the switch be ok?

See if you can find any nameplate data on the fans themselves on their power requirement. If you mulitply that by 3, that will be the requirement of the switch you buy.

I don't know what kind of fans you have, but the ones I am familiar with are the same ones the truckers use, and they look like they use their fair share of power. They are all metal and turn very fast.

The fans are the little cheap plastic fans (from W**mart) that plug in to the cig lighter and clip on the visor. The info I got was that it can run on any 12v power and it has a replaceable 800MA time delsay fuse. The switch I bought is rated for 30 amps. I have an inline fuse from the battery to the new fuse block with a 30 amp fuse and the fuse block now has a 5 amp fuse. 800ma comes out to 3.2 amps. I'm not sure I have this right. Should I get a new fuse block and get a 3-5 amp slowblow glass fuse or will the current setup work? I haven't installed it yet but plan to get it all working tonight.

If we assume the fans will draw 800ma(they will not of course, it will be something lower than the fan's fuse), 800ma x 3 fans = 2400ma or 2.4 amps.

The 5 amp fuse will work fine. The fuse is installed to protect the wiring. So a 5 amp fuse will protect a 18 or 16 guage wire to feed the fans(18 or 16 is a rough guess, 16 is good for 10 amps).

Keep the fuse coming out of the battery 30 amp, run a 10 guage wire from the battery feed fuse to the new fuse box, and you will have 30 available amps of power in case you want to add other loads to the new fuse box.

Looks like my math skills pretty much sucked today. It is 2.4 amp not 3.2. I mounted the fuse block, poked a hole through the firewall and ran the wire that will feed the switch. Hopefully tomorrow I can run all the fan wires and possibly mount the fans. I will be cutting little notches out of the trim that covers the cap seam so when the wires enter the trim, they won't be pinched between the trim and the roof. I don't have much time after work so progress is slow until the weekend.

Thanks for all your help.
Tom.