Weird Air Vents

I think there is something wrong with my air vents, or this may be normal I am not sure. During the day, hot air will blow at my feet all the time unless the air conditioning is on, and at night I can never drive without the air on, because the windshield fogs up because I think outside air is coming in from the top vent. Any idea what this is, and how to fix it? Thanks a lot!

man i have the same problem with my car i get hot air coming from the feet area but i have no idea what this is anyone have a clue it gets kind off hot down there