Chevrolet: Camaro A/C problem, ac system, stop leak

Question
I have a 1994 V6 Camaro with 180,000 miles.  I have recharged the air conditioner several times and each time it only lasts for about a week.  After that it starts blowing hot air again.  Can I recharge it with stop leak refrigerant without using a vacuum thing or will this only make matters worse?

If I need additional supplies to fix this problem, what are they and how much do they generally cost?  

Thank you for your time and your help would be greatly appreciated.  

Answer
I do not recommend using any type of stop leak in your AC system. It tends to cause other problems.
To properly charge an AC system you need to vacuum the system down to remove air and moisture from the system before charging. You should have the system checked for leaks and repaired properly.