In Command climate control info

[scuba dude]

Been reading about the In command climate control system and just wondering about the vent system. I have never tried it. I run my ac units when needed and they work fine. My vent is closed, vent fan off. I noticed you can open vent and turn fan on with flow in or out. What exactly is the function of this feature. Maybe to draw outside air in through open windows or what? If I want outside in I open windows and turn on Max air.