Now i have a good understanding of a 3800. But when i charge the ac it works, the next day it doesnt and the charge is half gone. Are these cars prone to have ac system leaks? and if so is there a way i can fix it without bringing it into a shop to have it worked on.

Depends on where the leak is. The quickest way to find a leak is get some leak detector and stop leak. Fill the system and run it until it gets empty again. Then go over the lines with a black light. It'll glow where the leak is. If it's an o-ring, you can replace it with a kit sold at most auto-part stores. If it's a pinhole, you can try a sealer made for that. If you can't find the leak at all, chances are it's in the evaporator core inside the vehicle.

thanks i will do this during the weekend

What Rook said.

Along with it. Recharge bottles are available with the leak detection and "stop leak". However keep in mind that is a temporary solution.

After you've fixed the leak, if you want it to keep working for a while, I strongly recommend taking it to a shop to have the system evacuated and recharged. Otherwise you'll be left with moisture in the system and over time you'll develop problems as a result.