A/C system

anyone knows anything about the A/C system on a 99 G20...there's no cold air coming out of the vents and my free on is fully charged....someone said it could be the a/c amplifier with some sort of electrical problem.... the car only has like 60K on it...is this common with the G20's.....if not what went wrong and how can i fix this and is it going to cost me alot of money to get it fixed?