We just put in a new furnace and AC. Our condo has 2100 sq. ft. There are three bedrooms upstairs. Two of the bedrooms cool/heat very well. The third bedroom is over the garage. We had a new garage door R-17 installed, 18" of blown in insulation in attic over bedroom and sealed inside and outside cracks. The temperature remains 12 degrees hotter and 15 degrees cooler than the other bedrooms. This bedroom has a cold air return and no vaulted ceilings. The other 2 bedrooms have vaulted ceilings. Three different HVAC companies have told us the only thing to do is put in another heating/AC unit for this bedroom only. There are Andersen casement windows and Condo Assn. won't allow window units.
Can you help please?