It seems liks the back bedroom room and loft vent is barely blowing air. Cold air is blowing from the vents but not as forceful as the other rooms.I do have vaulted ceilings in the down stairs that of corse leads up stairs to a loft and up stairs beedrooms. All the other vents in the bedrooms blow hard and cold from the upstairs ac. The house is built so I can't get to the the ducts because the way the ceiling is constructed. This problem is going on since I bought the house. Downstairs and the upper bedrooms are just great.