cm3

just got the compressor recharged so that the air can work. The problem is when I have the air on now the engines runs hot. Anybody know why this happens?

Bleach

When the A/C is on, there is extra load on the engine when the clutch on the compressor kicks in and a little more load on the alternator from putting out more power to run the fans. But I'm not sure how that would overheat your engine. The stock cooling system should be sufficent to cool the engine. It would seem that your radiator is not cooling enough.

Check the fluid level and make sure it is topped off
See if you still have the plastic radiator shroud around the fan. If not, replace it
Check to see that the radiator is not plugged with dirt and other "stuff" Clean it
If after all that it still overheats, get your radiator flushed. Maybe just buy a new one if you've got money for that. You can get a nice aluminum radiator from Summit for $179 (race only, requires custom mounting)