Our AC will not maintain 77F on these 90F days. By 2:00 it is 78F and by 4:00 it is 79F. I have looked at all of your ACs and find they are homes with: none, 2 ton, 2.5 ton and 3 ton. I had Jeff Richards, the Service Manager, of Northern Colorado Air, out to check ours and he says it is doing all it is supposed to do.
He has ordered a set of prints from the James Company and will recalculate the heat load. He thinks the designer may have not considered the 14 foot ceilings.
When I have talked to you about your AC those with 3 ton units say it ''does all we ask it to do.'' Those with 2.5 ton units say it is not adequate, or OK, but -----, or its adequate.
We all notice the difference in temperature between the first floor and downstairs, with the downstairs being 5F to 10F cooler. The difference is within the design guidelines for our type system. A more complex system with dampers and separate units would do better.
For the loft units cooling is shy upstairs. There are vent fans that you can buy that will pull additional air upstairs that might help.
I'll keep you posted on the outcome.