I have only ever heard of them blowing toward the engine either sucking or blowing through the radiator (to cool the radiator not the engine), fan blades are either left or right, meaning you have to have them running in the correct direction, the leading edge 'cuts" the air and the pitch of the blade pushes the air off the trailing edge in the direction you want the air delivered to, this is what determines which side of the radiator you'll have to mount the fan on.

An easy way to tell is that looking at the blade in such a way that the prop of the blade is concave the air will blow at you.