Heavy air flow coming in while driving.

[Rome Duran]

While driving my car, I have noticed that when the A/C is off, the front windshield vents still have heavy air flowing from them. When I’m in a stopped position, it doesn’t do it. It only happens while driving and I especially notice it when I’m on the interstate. It’s quite annoying any suggestions? 

[dcfish]

Replace the cabin filter first, Have a look at the opening after filter removal...Possibly some debris ...

[Vtallysx4]

Do you mean when the HVAC system is completely off? if so, put the HVAC system into recirculation mode, so no fresh air is pushed through the vent into the car.