2004 BMW X3

Air Conditioning problem
2004 BMW X3 6 cyl All Wheel Drive Automatic 92000 miles

My AC is blowing cold only on the driver side. The two vents on the passenger side are blowing hot. I had the system checked and recharged less than 1 month ago. Everything was fine. No leaks visible from dye injected. The system just started blowing hot on the right side all of a sudden. I've had the system checked by two independent certified mechanics/shops and each time the charge only lasts about a month or so. Yet no leaks. Am I looking at an expensive repair, such as an evaporator?
May 5, 2010.

The symptoms do indicate a possible evap core or expansion valve leak. They are difficult to access when looking for leaks. It might take some more " digging" to get to the root problem, exposing the core and expansion valve takes time, perhaps the previous repair facility did not go far enough.

Dr. Hagerty
May 5, 2010.