95 Sunfire AC Stop Leak

I have a 1995 Sunfire with an AC problem. We've had it fixed twice, but it goes out again after 2 or 3 days. Someone we know has suggested trying an AC Stop Leak. Any suggestions on a particular brand? We have 1996 Ford Pickup with the same problem. Any AC Stop Leak product suggestions there?

Any help would be GREATLY appreciated!

Joe & Christie