Which model do you have? Does the fan run when the nose is depressed, or just when the trigger is pulled? If not - check the head switch. Are you positive your fuel is good? Just because it feels full or you just bought it doesn't mean its good - check the date stamped on the bottom of the cylinder. It can also be a bent probe (the part that contacts the work) - if it is bent it won't allow the cylinder to travel far enough to make the head switch.
Answers & Comments
Which model do you have?
Does the fan run when the nose is depressed, or just when the trigger is pulled? If not - check the head switch.
Are you positive your fuel is good? Just because it feels full or you just bought it doesn't mean its good - check the date stamped on the bottom of the cylinder.
It can also be a bent probe (the part that contacts the work) - if it is bent it won't allow the cylinder to travel far enough to make the head switch.