How to build a motor reverser?

I have computer fans that I use as fume extractors when I solder. I would like to know if there is something that I could build to reverse the direction of the fans. 

On a slightly related note, I have a netbook cooler with 2 fans in it. I have tried reversing the polarity but they won't spin the other way. Can someone help? There are no diodes in the circuit, I have checked. I think it's because the fans can only work if hooked up properly, can someone confirm?

Super_Nerd6 years ago
The fans are probably brushless to be more efficient. Brushless motors use hall effect sensors to detect magnets and switch elecromagnets. The simplest way to reverse the fan would be to turn it manually.
A bracket, that lets you turn the motor around. These motors are not reversible. They are brushless, and contain three sets of coils which are switched in sequence

Unless you want to be able to reverse the direction of the fan at will, why don't you just turn the fan around the other way so that it is moving air in the other direction? Mounting it on a bracket like Steve mentioned, or on a third-hand unit so it can be positioned or reversed easily might be the easiest solution.