Fan running excessively on PB; how to clean

[swindmill]

The fan on my 1.5ghz g4 has started running constantly. My old PC notebook did this when the fan got too much dust, etc. in it, and I usually just sprayed the heatsink with canned air. What's the best way to clear up the fan/heatsink on a 12" powerbook?

[blackpeter]

I would use a can of air duster. There are vents at the back of your PowerBook. Perhaps you can use those.