maurice wrote:
Basement is definitely warmer than the main floor.

As for the ducts, I had them cleaned very recently, which didn't
help. No obvious leaks, but there is pretty weak airflow through
them. I actually partially close vents in other rooms to try and
boost the air flow in the living room, but it doesn't seem to do much.

That sounds like maybe there is some sort of flow problem How are the
filters, clean free flowing? Does the fan offer more than one speed?

It may require an on site inspection by a pro to find the real issues.
It can pay for itself.

--
Joseph Meehan

Dia 's Muire duit