Why do I only have air flow from the dash vents no matter which mode I choose? on 2011 Ford F-250 Super Duty

Can't get air from all modes only the dash vents, wondered if cold weather was a factor but I verified that was not the fact. Is it a vacuum concern or a sticking blend door?

Asked by for the 2011 Ford F-250 Super Duty
poss warranty at dealer
check the blend door to see if the heater box is broken ,fords are famous for this,also check to see if the actuator is working
Mode door!
2 more answers
Selector control switch could have failed, you would want to have it checked out...
unknown problem