I really do not have any useful experience with the reliability or quality of various central a/c units. My mother was just quoted a price for a York unit that seems fair (lots of ductwork to make it work as the old 4" supply ducts are way undersized for cooling and they, along with adding some returns to work well is a fairly large amount of work). He spec'ed a 13 SEER unit and when queried about a more efficient unit, he said it wouldn't perform well unless the furnace was changed as well - to meet the rated seer on those, it would need a unit with a more capable fan and controller rather than the single speed unit in the existing furnace (which, while oversized, he said was in great condition). Any thoughts? This guy only installs York equipment. Has good references. Probably should get some other quotes. I tried to get her to consider a mini-split, but she doesn't really want things hanging on the walls, and there are only a few places where you could put one through the ceiling, so that's out. I think that may be her better choice, but she's stubborn!