Grinder613,
Recently purchased a 2007 Aspect on the Ford 2006 E450 chassis. On our first trip, turned on the air conditioner found that it only blows air thru the defrost vents.
Found two places under the hood where the rodents chewed a hole in the vacuum line. Fixed those but still have a problem. Have not been able to trace the line from the engine compartment to under the dash. Expect to find more holes. Don't have a repair manual so have not been able to figure out how to take some of the panels off. Grrrrr......
Will be interested in what your discover.