How did it do other years for cooling the second floor.
This will only be our second summer in the house. It developed a freon leak last summer as well. Performance deteriorated until we figured out it was leaking and had it fixed. Seemed to work OK after that, but we only ran the AC for a month or so after we had it fixed.
A mistake that is some times made on 2 sorty houses. Is that they only consider the floored area for the second floor. And list the wall areas of the open areas as first floor load.
Then the second floor becomes undersized, and the first floor over sized.