If one floor of your home is always a few degrees off from the rest, the air conditioner isn't necessarily too small. More often, the problem is how the air gets from the equipment to the rooms.
In many Richmond-area homes the ductwork runs through a hot attic. Crushed flex duct, disconnected joints, and missing insulation can lose a surprising share of the cooled air before it ever reaches a register. Leaky return ducts can also pull hot attic air straight into the system.
Before anyone recommends a bigger unit, the ducts should be inspected. Sealing joints, straightening and supporting flex runs, adding insulation, and balancing the dampers can make a noticeable difference for far less than new equipment.
When we install new systems or change out old ones, we look at the ductwork as part of the job. The best equipment in the world can't make up for air that never reaches the room.