My mother-in-law drives around in my old 740 and has just passed the 200K mark. She says the A/C isn't doing anything or very little. This vehicle has had a new condensor put into it along with a new compressor and evaporator. Her mechanical abilities are very limited as is her English. She is telling me that she sees frost on the compressor. Is this possible? Compressors get hot if anything. They don't serve as expansion chambers. Can frost form on any part outside of the evaporator even in a dysfunctional system?