On Sep 10, 1:46*pm, Aaron Fude wrote:
Hi,

My central air unit is on the 3rd floor. When it's on, the air flow on
the 3rd is tremendous and it becomes cold in a second. At the same
time, the air is barely coming out on the 2nd and the 1st floors. The
ducts are old, but I inspected the parts that are accessible and they
seem to be intact. What could be the problem here and what should I
try next?

Many thanks in advance,

Aaron

My furnace/AC is in the basement - where it belongs! :-)

Anyway, every season I rebalance the ducts so that more cool air goes
to 2nd floor during the cooling season and more hot air goes to the
first floor during heating season. Cold air sinks, hot air rises.

Partially close some of the upper vents to force more air downstairs,
but keep in mind that whatever cool air comes out of the upper vents
will also add to the cooling of the lower floors as it sinks.

The ideal case would be electric dampers tied to a central controller
which takes input from three thermostats and continuously balances the
system as the air rises and falls.