How many tanks now? I guess it is possible that the A/C can't keep up, but if it is having a hard time keeping the place cool (before the tanks?); then maybe a tune-up will help.
I know my "little" 8k A/C dehumidifies the 1st floor over 1000 sq ft very quickly. Makes it feel a LOT cooler then outside, with only a 3 degree temp change