I had installed Core Temp after I began having some sudden black outs; after quickly figuring out the high temps were forcing the shutdowns, I began researching a fix for the problem and was afraid I would have to take the machine apart (which you end up doing to get to the fan) to fix it.
I ended up trying the most simple suggestion. I took a drinking straw and flattened one end, taped of half of the flattened end for a more stream line flow of air; popped a piece of bread in my mouth to get rid of all the moisture in my mouth; then blew both through the exhaust backwards, into the heat sink, and forward down through the fan vents. I saw several plumes of dust when I blew from either direction, and when I turned my machine back on was amazed that it dropped from 80c to 35-40c while running processor taxing programs. It's seemed like a miracle.
Apparently a vacuum is a bad choice for this fix, because of static electricity. A vacuum conducts static electricity and can send it through your computer, though very unlikely.