Sealed tight, both ways
A well-sealed house keeps the cool in, which is good, and keeps dust, humidity, and stale air in too. The AC alone was never meant to fix that.
What helps
Better filtration, a fresh-air or purification accessory, and duct cleaning when the system has run for years. We size these to the house instead of selling the biggest box.
Start simple
Often a filter upgrade and a duct cleaning do most of the work. We will say so rather than lead with the expensive option.
