I had my '69 POA refurbished and set up to run 134a. It was working last year, this spring no cold air so I thought maybe it was low on freon. Mechanic gets good pressure, no bubbles and the expansion valve ices up from the bottom nut down the line to the evap core, but the POA doesn't cool down at all and never frosts up. The air inside is maybe 65 degrees so it's cooling down somewhat, but obv not enough. Mechanic thinks the POA is the problem but I think it's something else. He said it seemed like there was too much oil in the line and he drained some out. Afterward everything cooled down nicely for a short time, but then the pressures dropped and the POA warmed back up. Anyone have any suggestions? Thanks.