2002 Ford Explorer No air flow

Nick, When the vacuum system in your vehicle looses vacuum, the default position for the system is "defrost". You will want to check the main vacuum feed under the hood. It should be a brightly colored hard plastic tube, red,black,blue or white, that connects either to the intake manifold or to a seperate cluster mounted on the firewall. If this connection is good then the next most likely suspect is the mode selection control on the dash. The control isn't hard to change. The only thing is you don't want to try to pull the dash panels out if it's cold. The retainers are prone to break if you do.