Electric cooling fan ?

[HOrnbrod]

Yeah Pete, the Tupperware is a great weather-proof enclosure, but I would be afraid those wire nuts would vibrate off eventually. I like to solder and heat shrink wire connections.

[comancheman]

i know little to nothing about wiring so here's a dumb one:

a relay has 4 posts coming off of it, if i wanted to run my fan just off a switch in the cab what do i do with all 4 posts? why can't i just have a power wire from the battery to the switch and then from the switch to the fan and then a straight ground from the fan

[Kenosha Warrior]

a relay takes the heat, not the switch.

 

no relay no fuse means hot switch and possible meltdown.

 

it should go

ground

power

switch

(device)

 

so there is a lead that goes to the switch. the switch should take another power and ground

[HOrnbrod]

i know little to nothing about wiring so here's a dumb one: a relay has 4 posts coming off of it, if i wanted to run my fan just off a switch in the cab what do i do with all 4 posts? why can't i just have a power wire from the battery to the switch and then from the switch to the fan and then a straight ground from the fan

 

Not a dumb question at all. The problem with running high current devices (like an electric fan) directly through a switch is because of the high current (amp) draw of the device. An electric fan probably needs 15A startup amps or more to start. Most switches are rated at only 15-20 amps, so it's pushing it right to the limit. You can use heavy 10 or 12 gauge wire, but the switch is still the weak point of the circuit. The solution is to use a relay. The four contacts on the relay are the + and - coil contacts, and the + and - load (fan) contacts. The relay coil is wired to the switch, which energizes the relay through the coil, requiring very little current draw, and protects the switch from frying. When the relay energises, the load contacts close, energising the device. One of the load contacts goes to a 12V power source; the other to the load. The load contacts are wired with heavier gauge wire, and the relay is located as close as possible to the load to minimize voltage drop. You can also use the relay to turn on the ground, instead of power.

 

That's why it's best to use relays when upgrading headlights on our rigs, because there are no relays in the headlight circuit, and the headlight switch (or the wiring) is the forst to fry, and the voltage drop through the stock anemic wiring does not allow full power to the lights. Hope this makes sense.

[comancheman]

so basically the relay has a power in and a power out and a ground in and a ground out???

[HOrnbrod]

This URL will help:

 

http://www.ado13.com/techs/relay.htm

 

The pin numbers on most all automotive relays are the same as the URL describes.

[JeepcoMJ]

This URL will help:

 

http://www.ado13.com/techs/relay.htm

 

The pin numbers on most all automotive relays are the same as the URL describes.

 

very helpful...maybe now I'll route the fog lights through a relay in my camaro control center rather than straight through the switches...

 

:P

[JohnQ]

I put my relay's on the inner fenders next to all the other electrical stuff.

 

I'm thinking about using Pete's tupper-ware idea to keep them dry.

 

 

Pic of my electric fan installed.

 

 

This is where I mounted my fan switch. It only has power when the key is on.

 

[87manche]

I put my switch in that same location, but I wired it to run even with the motor off.

so I can turn off the motor on the trail and still run the cooling fan to cool the power steering cooler and to limit the thermal expansion of the coolant when the motor was shut off from the heat soak in the block.

[JeepcoMJ]

put a stock switch in there, it will look nicer.

[87manche]

put a stock switch in there, it will look nicer.

 

have you seen my truck?

[JohnQ]

put a stock switch in there, it will look nicer.

 

 

I like the look of my walmart switch! :D

[JeepcoMJ]

i was talking to johnq...his truck is kinda a resto/mod truck IMHO. it's wheelable and could easily be made show-truck.