Okay. Still likely picking up heat in the attic since very few duct systems are fully sealed and well insulated. Next cooling season, you might want to take supply and return temperatures both at the furnace/coil and at the supply registers/return grilles to compare them. Ideally your supply air is ~ 55-60 deg in cooling. My own system generally has colder supply air, but most of my supply ducts are within conditioned space and have minimal leakage, so that makes a difference. My return temperature is also ~72 deg which makes a difference. Your return air is likely picking up heat before it reaches the blower and could be closer to 80 deg. Similar situation for supply air in an attic system.
Originally Posted by 545GAlady