It's supposed to do that unless you set the air vents to "recirculate" mode?
I've had this problem with my Getz for a while. With the fan switch off and set to blow air from the face ducts (or whatever they're called) I do not get air blowing through the ducts when the car is stationary. However, as soon as the car starts moving, air starts blowing through the ducts, with more air being blown the faster I drive. Now, I recently replaced the radio in the car which involved removing the glove box and the panel underneath the steering and I can't help but feel that now the problem is even worse.
What do you guys think could be the cause of this problem and how could I fix it?