# How to wire an LED switch



## Baron1 (Mar 9, 2011)

I'm trying to wire up a couple of small computer fans to help cool my motorhome 'fridge.
The switch I am hoping to use has a blue LED light incorporated in it which I understand has to be wired in the correct polarity, my problem is so do the fans!!
If I wire the switch so that the fans come on the light doesn't and vice versa.
The switch has three terminals marked earth, A and +ive.
I think I've tried every permutation (including blowing a couple of fuses)

If anyone out there can help with this it would be much appreciated.

Rgds Mel.


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## Techno100 (May 8, 2010)

The fans will just run backwards if polarity is reversed

I imagine +ve is the feed A perhaps for Accessory? "load" and earth -ve

My fans, Ive since removed the centre one or it would take off :lol:


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## radar100 (Sep 8, 2010)

Hi Mel, based on your description of the terminals I would say that +ve would be the 12v supply, A would be the switched output to the fan positive, and earth would be just that, the 12v negative and that the fan negative could also be connecte via this.

Hope this helps

Radar


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## Techno100 (May 8, 2010)

:lol:


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## sideways (Jun 2, 2008)

Your live feed will go to the positive on the switch , A will go to the positive on the fans the negatives of the fans go to earth and the the earth on the switch goes to Earth, if you get the fan polarity wrong they will suck instead of blowing, The switch will need to be earthed for the light to work although the fans will work without the switch being earthed,


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## Techno100 (May 8, 2010)

Yes what he said :lol:


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## jonse (Nov 2, 2008)

*Fans*

Didn't think it got that hot in UK to need them Ha Ha :lol:


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## Baron1 (Mar 9, 2011)

I have tried reversing the polarity to the fans and they don't run, this is, I think, the problem.
Mel.


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## Techno100 (May 8, 2010)

I think you have your wires crossed on the A and the +ve.
The LED should only come on when the fans run.
Were you careful to get 12 volt fans? some PC fans are 5volts


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