This has been an issue since I purchase the house however I have never really addressed it. Unfortunately it cost me last month. I've always had to lower my thermostat to cool this room. My room is noticeable warmer in the winter and cooler in the summer than the entire house. The side closest to the unit at times doesn't even need to be cooled because it is so much cooler than my room. I've been trying to educate myself online however I don't know where to start. I (believe) I understand somewhat that the room needs to circulate air (in and out) well. The room has 2 vents however I'm not sure if enough air is getting into the room. Aren't there dampers that control the amount of air going to the rooms? If so where do I locate them. I'm assuming that the rooms that are cooler could stand to have less air going to them. I have all the vents open in my home except our laundry room. Any more info needed I will be happy to supply.
I'm not sure if this matters but the previous owners built an above the garage room in the home. One of the walls of the above garage room I believe is above my bathroom.