AC doesnt work

i have a 94 pontiac grand prix that when the ac is on it blows hot air do i need a recharge or a new compressor where would the ac purge thing be if it needs recharging thanks

Go to your local autoparts store, and get the A/C leak detector that shows up in a Blacklight. Use that (with the blacklight) to see if you have leaks in the condenser or any of the lines. If its a leak, you'll either have to replace or just fix the part. If you're re-charging your A/C and its not lasting long..that means there's a leak.

I just discovered a leak in the condenser of my '97, using that method.