Yes, the BMW X5 has an AC expansion valve. Very common problem (valve sticking or freezing up) due to under use or low refrigerant. Mine was very low on refrig, just had it serviced, and the tech said I was very lucky not to have problems with the valve.

On a side note.......everyone should cycle the AC system for a few minutes in the winter time once a month. This keeps the system from freezing up.