I have a goodman high efficiency gas furnace and air. When I use my air conditioner on med. Fan it doesn't seem to push enough air. When it is turned up to high, the fan makes a loud roaring noise but pushes more air. I have had a couple hvac people look at it. One guy said my cold air return was causing the problem, the other said I needed new duct work ran through the house. Neither one of these seem right to me. I took the cold air return loose and it didn't help. The other hvac guy wants 3000.00 dollars to run new duct through the house but won't guarantee that will fix it. Has anyone else had problems with furnace and air making loud noise on high only?