Very possible there is a damper in the cellar that is partly closed.
Here is a picture of the ones typical near me.
http://www.hvacsolutionsdirect.com/i...lar%20AR-1.JPG

If the handle is in line with the tube, it's open. Across, is closed.
Two adults with walkie talkies can trouble shoot that pretty quick.
Sometimes if the adult upstairs bangs on the duct with a metal screw
driver, the one downstairs can tell which duct it is. Yelling into the
duct from above can also help pinpoint.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"annur" wrote in message
...
My tenant recently complained about one of the bedroom upstairs being
too hot. When I checked the vents in the floor (there are 2 vents) in
this bedroom, one of them has more air blowing than the other one. I
also checked all the rooms, and there is more air blowing on all of
them. Except this one vent in the bedroom does not have enough air
blowing. For this vent that has a problem, I opened the vent and
checked if there is anything stuck which I did not see and everything
seems to ok as far as I know. Is there something I can do to fix this
problem?


Thank you very much for your help.

Annur