Replaced a/c compressor, evacuated and charged a/c, tested for leaks (found none), replaced a/c belt, replaced receiver dryer, replaced expansion valve, flushed a/c lines.  I had cool air (not cold - about 60 degrees at vent) for about three days.  Now the air is neither cool nor dry.  With the a/c switched on at start up, I hear a squeal.  Accelerating eliminates squeal and it doesn't return.  Belt is tight.  Everything seems to be right but, something isn't and I can't figure it out.  Can anyone help me diagnose and fix this?