AC belt question

[87bucketgta]

Hey guys I have a stupid question, I have an 83 ho 307 all stock. Right after I got the car I converted the ac to r134 since the compressor didnt work anyway. So I not sure if this is an compressor problem or what. I keep going through ac belts. I cut the ac on and the belt has alot of bounch in it. So much U can actually see it hitting the lower radiator hose. What Im trying to figure out is it my compressor or my pulleys how can i check? To add, when I first put the belt on it seems fine, but after i run it a few months it gets more and more play to it, and I got it as tight as I can go. Thanks in advance