Heater fan control

On my 2006 Equinox, I have an issue with the vent selection. I cannot seem to get the heat to come out of the floor duct only. With the selector knob in the floor position, I still have some hot air coming out the defrost vent. If I turn the knob just a hair to the left a small amount of hot air starts coming from the vents. While most of the air is coming from the floor, some air always comes from either the defrost or vent. Probably about an 80/20 ratio. It's enough hot air in your face to really irritate me, and suffocate me. I wish I could get 100 % of the air to come from the floor like in every other car I have ever owned. Is this common to all Equinox's or does mine have a problem? Can you check yours and let me know? Thanks.

Mark