Your diagnostics would seem to indicate exactly the conclusion you have come to. As such, depending on the age of the unit, it probably had the old-style freon in it. That stuff is hard to come by and is very expensive...at least here in the US. Plus, if a tech will have to cut the line to put a vacuum on the system and then put the freon back in and then hopefully get the line re-crimped good enough that it won't all leak out, and hopefully the original leak's not in the expansion/radiation coils where you can't fix it....well, I can see where that's going to get pretty expensive pretty quickly. I think I might be looking towards replacement instead of repair. Just my thought pattern on it.....