No Matter what switch is set at, air only blows out the panel vents. How do I trouble shoot this, I live in Alaska and must have my defroster. All fuses are good, Temp selector good, Fan switch good, blower motor good.
first thing you should do is have your hvac system scanned for codes. Your mode door motor may have a problem, or the control panel is not sending a signal. #6 is the mode motor #8 is the floor motor #10 is the defrost motor