Thank you for the info.

To answer some questions posed.

House is a 1200 sq foot upstairs with 1 vent in the mostly closed off basement. I live in middle TN which puts me in the area of middle of the road everything except pollen. Heat, Cold, Humidity are in the middle of the spectrum.

It is an older nordyne split unit unit with a direct drive motor on the squirrel cage. I upgraded the HP of the motor not because of performance but the original was an 1/6 HP and locally I was only able to source 1/4 and 1/3 hp's. The one I replaced it with was the same RPM but less amperage draw than OEM. Obviously new motors are more efficient.

I clean the condenser coils several times a summer to maximize efficiency and because it picks up lots of visible debris. I clean the evaporator coils at least once a year.

The comments on register flow and humidity all make a lot of sense. The one register in the basement used to feed one of two vents in the living room but when the previous owner decided to refurb the basement he opened it into the basement. I am gong to look at obscuring it at least partially and see if it helps. It is the first duct off of the main duct and it is literally 1 foot off of the main box duct. I'm sure it is probably taking to much out of the system. We don't use the basement for more than storage and laundry.

It is probably time for a new unit but I am trying to eek a few more years out of it.

I really appreciate all the advice.