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correct wiring for installing auxiliary electric fan w/switch


starfireelvis

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I am installing a pusher fan in front of the radiator, that I would like to control with an auxiliary toggle switch, as I do not want/need the fan to be on at all times, only during long idle/slow speeds. The fan already is set up from the factory to be a pusher fan.

Want to run the positive wire through the firewall back to the toggle switch, which I want to mount out of view under the dash. Can the wire run straight back to the switch, or must it be hooked at some point to the positive terminal of the battery, or to the fuse block at an auxiliary port? Will be using a 20 amp fuse if necessary.

Also need to know the best recommendation for routing the negative wire from the fan back to the switch.

Also inform me of any other considerations I need to address.

Want to keep this simple, and straightforward, do not want to have fan running all the time with a direct connect to power. Thanks in advance...

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Don't run both wires back to the switch. I would take the negative wire and ground it to the chassis somewhere close to the fan. Then run the positive wire from the fan through the firewall to the switch and then another wire from the switch to a fused positive feed in the fuse box.

Frank

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Starfireelvis, Is this a 12V Negative ground car? If not you would have to adjust wiring to accommodate the difference. Also 20 amps is pretty big for a small fan motorcheck the draw on the specifications and go with as small a fuse as allowable - wiggle room on fuses helps cause leaks in the wiring - those leaks let the smoke out and then the wire stops working!!! :)

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Thanks for all help and feedback; installed fan today, switch and all, works like a charm; hopefully will be effective when necessary.

Sambarn, should have mentioned my car; it's a '62 Olds Starfire, which has a negative ground; good point to mention though for anyone referring to this in the future to take that into consideration. The 20 amp fuse is what was called for per the instructions for installing the fan.

Biggest challenge was having to slightly adjust the hood latch lever to accommodate the fan; thankfully there is a top shelf deck that completely covers the area between the radiator and the front grille, so it does not alter stock appearance one bit; also the switch is tucked in very inconspicuously underneath the dashboard, within easy reach.

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If the instructions call for a 20 amp fuse I'd be putting in a relay. Then run a wire direct from the battery terminal through a fuse to the relay. Your switch then just goes to the relay as well. No point in having additional electrons running around under the dash if they are nor required.

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  • 2 weeks later...

Update--I did have the relay added to the wiring this weekend; thanks for the advice, ounce of prevention is worth all the cure in the world.

I have used the fan on two occasions thus far where I have had to idle for an extended period of time; neither time did the "hot" light come on, and I am certain that it would have prior to adding the fan, so keeping fingers crosesed.

Also, has been eight years since I replaced my water pump (have put on about 29k miles since then); so as preventive maintenance, I have put on a correct '49-'62 water pump for A/C cars; any thoughts on if this would help keep the coolant temperature down?

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hi starfireelvis, has the original radiator been replaced ?, i wonder if it has been replaced or recored, if it now doesn't have as much cooling capacity as the original a/c equipped olds radiator did have from oldsmobile. what kind of fan is bolted to the waterpump shaft ?, how many blades ?. charles coker, 1953 pontiac tech advisor.

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