Mystery AC vent

[kevinr1970]

I had my dash bezel off my '86 GMC this weekend.
I noticed that I have what I assume is supposed to be an AC vent on the lower left corner of the dash. It is to the left of the headlight switch.
The strange part is that:
1) The vent goes nowhere, there is no ducting routed to it
2) Even if there was, their is no hole in the bezel for the vent - it is hidden behind the bezel
3) My truck is not an AC truck - never has been
I am pretty sure the bezel isn't the original for the truck, but it is for a non-AC application.

Another interesting thing was I pulled the bezel off my '85 GMC parts truck that does (or had anyways) AC. The bezel has a vent in the upper right corner, above the radio, but it doesn't have a vent hole in the bezel in the lower left location. It was dark and cold when I got to this point last night. I am going to look tonight to see if it has a mystery vent down there too.

Just sort of strange to me?

[piecesparts]

My truck (84) and my son's truck (86) have the vent holes in the bezel at the lower left and at the upper right corners. They are both connected and work. The lower left vent is connected to the heater box by a long tube that goes across above the drivers feet to just behind the ash tray. It slips onto the heater box there. The tube is not round, it is oval in shape and looks a little like a dog's leg.