Why is my a/c blowing hot air when I put my a/c on? on 2001 Cadillac DeVille

Was installing a radio yesterday shortly after the air was blowing cold then all of a sudden it started blowing hot air the compressor is on but making funny noise the coolent is almost full

Asked by for the 2001 Cadillac DeVille
COULD BE MANY ISSUES SEEK DIAG AND EST