Why does my van emit hot air at the floor vent when the fan, ac/heater are off? on 2008 Chrysler Town & Country

When the weather is nice and I want to drive with the window down or when it is just right and I do not need the heat or ac & I have them off, my van emits hot air. Sometimes the air is so hot that I have to put a big piece of cardboard between the gas pedal and the vent in the middle front console to keep it from scorching my feet and legs,

Asked by for the 2008 Chrysler Town & Country