91.5 w250 replaced bad comp.,exp. device,drier etc.cleaned everything and charged with 2lb,8oz.134.suction line sweating but cool ony 58 degrees.90 ambient and heater seem to do the same thing .Hot at first and gets too cool almost cold on long winter trips.Replaced several bad vacuum lines over the years and brakes feel good.Any ideas or common problems on these old trucks?