Will it pull out air?

[45 sheeps on the road]

Will a CPU water cooler fan pull out air?

 

[onichikun]

Will a CPU water cooler fan pull out air?

A water-based cooling system uses the higher specific heat of water (~4x that of air) to move heat away from the component being cooled, and to a radiator with a large surface area. You still need to cool the radiator, and people typically use fans for that.

So yes, you will likely be pulling air out of your system, since you are blowing through a radiator.