Join Date: Jun 2009
Location: Southeastern Pennsylvania
By upper vents, you mean the ones in the face of the dash? If the hoses, control, or vacuum motor fails, the fail-safe is to route the air to the defroster. Are the big hoses from the blower connected to the dash vents? Probably, it would be odd for all three to be disconnected.
Amateur restorer. Well, sometimes I have been paid for it. But not right now.