Your AC is cranking in your living room, but somehow it just doesn't seem to be doing its job. You look around and realise the cool air is unnecessarily leaking into other parts of the house, like the hallway and corridors.
Consider...
Installing cavity or pocket doors in the various doorways that lead to your open plan area(s).
Air conditioners of different sizes are rated to heat/cool a maximum volume of air, so if you can close off the open plan area, you'll notice a much better result.