2001-2005 Passat front window defroster

The defrost duct on these cars is small and centrally located, when I tried the fan little air seemed to reach the left or right sections of the windshield. I will be driving in extremely cold weather ( - 40 Celcius ) and was wondering if other owners have experienced problems with the window frosting up or taking a long time to clear of frost.

I live in Minnesota (-40 C at times)and have driven an 04 Passat through last winter and a 99 Passat through the winters before and never had any problems with the defrost or the heat...