According to experts, a Central Air Conditioner Manufacturers performance depends at least as much on how well it's installed and maintained as on the equipment itself -- and in many cases, more so. "Furnaces and air conditioners don't just snap together and plug in, unfortunately," says Bill Brown, an Ohio HVAC contractor in an article at Angie's List. "So, we really are the guys at the end of the manufacturing line; it just so happens to be in your backyard, attic or basement."