kovalb said:
The A/C compressor does run in Defrost mode, and cannot be turned off. However in Foot/Def mode I am pretty sure it can be turned off. Same logic every Nissan uses.
In our Nissan S (2013), both the A/C and the Heat can be independently turned on/off in Defrost mode. (When you first push the defrost button, both are in the on state by default). If the window starts out clear and the car isn't fully loaded with humidity-producing humans, defrost mode with no A/C and no heat on the lowest fan setting tends to be enough to keep it clear.
The one thing you are absolutely not able to do---even in foot+windshield mode---is turn on recirculating air. Presumably it would result in a very quickly fogged window in cold weather. I have wondered though, whether one would be able to get a way with heat+A/C (for drying)+recirculate to both heat the car efficiently (recirculating air) and keep the window clear. I'll never know!