[mwg0415]

My dad owned a 92 Camry growing up and he currently still drives his 97 4Runner. My 07 Tundra is my first Toyota, but I can honestly say that all three had this same thing. I assume it's just something Toyota does, intentionally or not, but I vividly remember his Camry doing it. It's just about impossible to stop air circulation in a Toyota.

Of course, you could just turn on the circulation button, then turn off your AC/heat. That'll stop it entirely.