Sorry for the essay but looking for a little input here.

We have a home with 2 systems installed when new 4.5 years ago. A 4 ton Condenser/Coil Carrier system cooling 2000 sqft downstairs and a 2.5 ton/3 ton condenser/coil Carrier system for upstairs. The downstairs seems fine and stays on its target of 74 all day long with fairly long cyles but not continuous running all day.

It seemed that when the system was new, the upstairs was able to keep up with our Texas heat but honestly, we did not even use that floor much in the first year or so. Then we added the movie equipment in the 500 sqft Theater room (which is over a 3.5 car garage) and had two kids that ramped up the use of that floor. The last couple of summers, that unit runs from about 8am until 3-4am the next day pretty much non-stop and depending on external temperature, lands between 85-89 degrees by the evening when set at 76. We know it is the theater room driving the heat as it is noticably hotter in there but it is insulated on all sides to fairly new home specs.

The unit has blown the capacitor 3 times but nothing else seems to be wrong. Charge is OK and everything else checks out including vent temp. Our guess, and that of those techs that have looked at it, is that the system is under sized at 2.5 tons and has been trying hard for 5 years now and is analagous to a newer car having 250,000 miles on it. Yes it is new, but it has had a hard life.

My quandry is how to upgrade it to get our desired cooling level. There is currently a 3 ton coil in the unit upstairs that seems OK so one option would be to just upgrade the outside component to 3 tons to match the existing coil. This sounds like the best idea and in fact is the recommended one by a couple of techs even though it is less revenue for them. This should give us about a 15% bump from about 31,000 btu (2.5 ton condenser with a 3 ton coil) to about 36,000 btu (3 ton condenser with the 3 ton coil). The other option is to replace both ac components with a 3.5 ton system but I am not sure if this would be overkill.

I just want it to be cool. I don't want to go the cheaper route just to find out it will not do it either. I also do not want to oversize and get into the issues with that in addition to the extra money it would waste.

Any input?