Not as simple as that.....and I'm really surprised anyone will take one reply as the God's truth.
There are two sides to this question. Follow Alpha's directions or try it the other way. Blow air onto the alpha, ambient temp air ducted from the rear fan opening. Cooling this heatsink by blowing cool air on it will result in lower temps than sucking hotter air through it as is the norm.
You have to try it yourself to see the result. Not very difficult either.