electrical problem/question

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Master Wheeler
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electrical problem/question

Postby eddie platt » Thu Jul 15, 2010 7:56 am

so im not all that educated when it comes to the mechanics of electronics. i just know to connect 2 wires and a switch and it should work right?

i recently installed an electric fan out of some other model vehicle, not sure what one. i have it all mounted up, wired the negative wire to the dash on a switch and back to the battery, and ran the positive through a fuse and right to the battery.

heres my problem. im not sure if the fan is drawing too much juice or i just have it all wrong. its melting wires and the other day i had the fan running for over 5 minutes in one stretch and i pulled in the driveway and the switch wouldnt turn the thing off. it had melted the switch and fused it in the on position permanently. so i had to disconnect it from the battery.

what could be causing the wires and switch to get so hot? do i need to use bigger wires? i guess i got lucky, i dont want this to burn my rig to the ground.

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Postby broncomarc » Thu Jul 15, 2010 2:39 pm

Mechanics of electronics? :lol:

It sounds like the fan is pulling too many amps. What gauge wire are you using and how big is the fuse? It's surprising that it would melt the wires and the switch before blowing the fuse. It is a used fan? May have some kind of internal short causing it to draw too many amps.
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Postby Jerry Blair » Thu Jul 15, 2010 3:35 pm

Eddie,

You are definitely pulling way too many amps for your switch. You need to wire in a relay. The relay used in conjunction with an appropriately gauged wire will keep the Jeep from burning down.

Here is a good link that explains relays:
http://www.the12volt.com/relays/relays.asp

How to choose size for wire:
http://www.offroaders.com/tech/12-volt- ... e-amps.htm

Fan wiring diagram:
Image

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Postby Jerry Blair » Thu Jul 15, 2010 3:37 pm

If you replace the thermostat in the above diagram with a switch, your fan will be manual in operation.

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