Hey guys, sorry if this has been repeated many times but I have a newer house, less then 3 years old, I have a Lennox 13acxn out door unit. It does well for the most of my house but in the master bedroom it is 20 degrees difference, I have put a camera down the vent and can feel air come out, but the room is so miserable we have multiple fans running and still can't seem to cool it off. My question is what are some things I can do? We can not even sleep most nights.

Update: if anyone is curious, I could not get proper air flow from the one register in the room, I ended up putting a second in the room that had much greater air flow, it has succeeded and the room is not at a temp in line with the rest of my house.

Thank you all for your help.