Dashboard Vents not working

[KDtraveler]

I have a 2016 Thor A.C.E. 27.1. There is no air, heat, A/C or fresh air, coming out of the dash board vents. I can hear the vent fan running and air comes out of the windshield vents. Has anyone had this problem?

[Sappy2]

The mode switch is likely not getting vacuum or has a break in the vacuum control hose(s). When the mode switch has zero vacuum, the default is to send air to defrost vent at glass. And, I am assuming you have the engine running. There are a number of reasons for the issue, like a vacuum canister that is leaking, lines cut (or chewed on by critters), disconnect of vacuum source at engine, etc. I do not know if yours is a class A or C with a Ford chassis, or not.