Check for evidence of leaks (oily residue) where the system pipes connect to the condenser and compressor. It is not unusual for the O-rings in those fittings to deteriorate. An inadequate refrigerant charge will cause the evaporator to be "super-cooled", resulting in the ice up condition.

2002 X5 3.0 236,000 miles
2004 325i 105,000 miles