I have seen a similar problem caused by a slipping drive belt. There is a magic system that shuts down the system for some reason if the belt is slipping on the compressor. Granted, this happened in the heat of the summer, but it is related to your problem.
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in