My wife's AC has been out for about a year now. About a month ago I paid a Mechanic to do a diagnostic and he said there was a leak in the evaporator core. So I spent about 40 hours replacing the evaporator core and expansion valve. Recharged the AC and it is still blowing warm - hot air. Any thoughts on what may be causing this? Thanks. Oh, we are dealing with a 1993 300E