OK guys i am working on a reach-in cooler that had the compressor changed out prior to me working on it.Customer told me it has not worked properly since compressor was changed. Its an R-12 compressor so i pulled a good vaccum and put r-414b in the system. Its a cap tube system and my head is around 190 to 195 with 20 psi suction. The box was at 85 degrees and dropped to about 65 then the compressor would go out on overload and was extremely hot, it comes on again a few minutes later and goes back out on overload after running for about 5 more minutes. I cant feel any return on my suction line it just feels like room temperature. The cap tube was never changed out. Any ideas on what the problem may be im getting stumped, a part of me wonders if the guy who put this compressor in put the wrong one in but i cant find a model and serial anywhere on this box.