A central AC replacement in Orange County costs $3,500 to $7,500 with existing ductwork, while a whole-home ductless mini-split system runs $10,000 to $18,000. The numbers look far apart until you factor in duct losses, which ENERGY STAR estimates reduce central AC efficiency by 20 to 30 percent before conditioned air ever reaches the room. Mini-splits eliminate that loss entirely, run at SEER2 ratings of 20 to 33, and last 15 to 20 years compared to 12 to 15 for central AC. This guide breaks down the full installed cost of both systems, compares 10-year total cost of ownership, and gives you the honest framework for deciding which one makes financial sense for your Orange County home.