After many visits by the HVAC company, I am still having issues on my second floor with regard to the returns and the temprerature.
Some background, 2500 Sqft brand new house, one 4 ton York unit. On the second floor (Master bedroom bath and 3 additional bedrooms and a second bath) it is always warm and never gets below 80 degrees even after the unit has been running for 2 days straight or more. There are returns in each bedroom. When the unit is running, it seems like there is dead air and almost no movement of the air. When getting a ladder and feeling the return vents in each of the bedrooms, they seem to not be drawing any air, even a tissue cannot be held to the vents. The return vents are maybe 14" square. The installers found that within the walls there were some issues with the return that goes all the way down to the basement that were repaired (wrong connects etc.).
In the attic, there is a rectangle box with 4 - 7" flex going to the returns in each bedroom and 1 large 12" flex that goes to the basement from the attic down the wall of the house for two floors and then to the furnace.
The second floor almost never gets colder than 80 degrees and most of the time is 10 - 15 degrees warmer than outside.
The company balanced the system and almost all air is blowing upstairs.
I appreciate any comments on what needs to be done to make our lives livable again so we can sleep and shower without sweating.