The airflow in one room, only, on the second floor is reversed. We just moved into a new (to us) home built in 1992. All heating and cooling are working great except for one room on the second floor where the supply and return seam to have been reversed. I can feel air coming out of the return, definitely, and I'm pretty certain there is air being sucked into the supply.

When we moved in I found a random duct "valve" (I put it in quotes like that because I'm unsure if that's really what it is, but it's the size of the supply (not a grate) and clearly would restrict or change the airflow when spun) in the basement. I didn't see where any duct work had been recently changed.

This room is the only one that doesn't properly cool in the summer or properly heat in the winter.

Has anyone seen this before and is it possibly and easy fix?

Thank you all for your help here!

Sound like someone got the supply & return ducts reversed for that room. If you know which ducts they are, it shouldn't be hard to switch them.

Or just swap registers.