Air flow in defrost mode

When I set the HVAC system to defrost only, I get air flow both at the front window and down below by my feet. When I switch to air flow to the front window and below - all OK - I get air in both places. I mentioned this to the dealer during a recent service visit. He said he "checked" another Stringray and it worked the same - therefore, that is the way it is designed. Normally not a big deal, but it can sometimes be annoying when you want air to the front window only and I get it to the window and my feet. Does the defrost only switch send air to your front window and your feet or front window only? Thanks in advance, Dave.