2001 Ford F-150 Air stops coming out of dash panel outlets

Hi Terry Kennedy. Welcome to the forum. Your HVAC controls are vacuum operated and that is the spring-loaded fail safe default in case of a failure. Your feet might freeze, but your windshield will be clear. Look for a check valve in the vacuum hose going from the intake manifold to the firewall. Replace it if you can blow through it both ways.

If the valve is working properly, install an updated valve with a vacuum storage canister built in. If Ford doesn't have one available, you can find them at your local Dodge dealer or in a salvage yard. The original valve is about the side of a stack of three nickels. The improved valve is about 1 1/2" long by 1 1/4" in diameter.

Caradiodoc