The cost of replacing an air conditioner varies widely based on factors like the unit size, type, efficiency, and installation complexity. On average, homeowners can expect to pay between $3,000 and $7,000 for a new central air conditioning system, including installation. High-efficiency models or systems for larger homes can cost upwards of $10,000. Additional expenses may include upgrading ductwork, electrical modifications, or adding zoning systems. It's advisable to get multiple quotes from reputable HVAC contractors to ensure a fair price and to consider long-term energy savings when selecting a new unit.