# 12 Volt DC Fans



## KellyW (Sep 7, 2007)

Just acquired two of the above to cool our sleeping area.

Wired a 12 Volt plug to both of them but when connected, shock horror, they suck as opposed to blow!

Will swapping over the cables affect the direction in which the fans go around?

O Level Physics seems to be suggesting that it will but before I take the plugs off, can someone quickly confirm my suspicions, please?


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## gnscloz (Oct 4, 2008)

yes just reverse wires unless theres a rotational switch on fan


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## KellyW (Sep 7, 2007)

Thanks for that gnscloz.

I thought as much, DC, direct current and all that.

With some fans of course the blades are reversible but on these they aren't!


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## Kees (Jan 15, 2009)

Hi

Sorry to contradict you, gnscloz, but reversing the wires on a 12 volt DC fan will almost certainly destroy it. There is an electronic drive circuit inside the fan. The red wire is positive, the black wire is negative. The only way to reverse the airflow is to physically turn the fan through 180 degrees.

Kees


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## KellyW (Sep 7, 2007)

Kees,

Fortunately, reversing the wires did work!

Many thanks all the same.


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## tonka (Apr 24, 2006)

Looks like Kees needs to go back to school  
and Kelly w just got a gold star..  
Most things on 12v dc would blow up but on the fan it's only operating a motor so will work... As proved..


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## Kees (Jan 15, 2009)

Hi tonka

I did say "almost certainly"!   

Most modern fans do not use a commutator to drive the motor, they use an electronic inverter circuit (which is polarity sensitive). I thought the old technology had died out but obviously not. Will a kindly engineer please come to my aid and confirm that I am not a complete a***hole? Or perhaps I am.

Kees


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## sallytrafic (Jan 17, 2006)

The fiamma ceiling fan is polarity sensitive and uses an ac motor driven by electronics as described


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