See about adding another return centrally located on an inside wall..i suspect you are short on return air...you need a minimum of 1200 CFMs for good air movement and comfort...

TD

With a well-designed A/C duct layout they will usually install air returns in each bedroom, and one or more air returns on each floor in the main living areas. Everywhere you are pushing cold air should have an easy path for return air.

It sounds like additional blocking of sunlight in your rooms might also be a good idea. You could add solar screens or insulated drapes, but the best solution might be some type of exterior awning to shade the windows.

Bruce

For Bruce....unfortunately central returns have become the norm rather than the exception. Most condos have poorly designed and sized duct systems especially two story units.

TD

Have you always had this problem is it something that started recently? Do you get good air flow at the supply registers in the bedroom? When was the last time the AC was serviced?

A 2.5 ton AC should be able to cool a 1200 sq. foot condo. Try closing the vents in the living room. This may help compensate for the duct work issues. You can also install room darkening drapes in the bedroom to further block the heat gain from the sun.

If closing off redusters in the living room helps, a more permanent solution is to choke off the air supply to that room at the trunk/branch line. This will reduce noise (whistling) that occurs when you close off room registers.