I have a two-story house with upstairs and downstairs HVAC units, and I recently converted the attic to liveable space, relocating the ducts to the floor perimeter.  I put in registers in the attic to include the attic in the conditioned area along with the upstairs, a total of about 1600 square feet, which I understand my 4 ton hvac unit should be able to handle.   The AC works fine until the temp reaches around 82 degrees in the house, and then the AC will not cool down below 76 degrees, leaving it uncomfortable in the upstairs and especially in the attic.  The eaves are vented, and there is insulation in the attic walls, and on the attic floor, and there’s one vent near the top of the attic room.  Would it help to double wrap R-6 AC ducts located at perimeter of attic room? An AC contractor said it wouldn’t, since the flex ducts are already approved for attic use.  Would it help to install a return in the attic closet that houses the air handler unit?