If your AC unit is older than 10 years or needs major repairs, it may be time to consider replacing the entire system. The cost for a new air conditioning system can range from $3,000 to $7,000 depending on the size of your home and the type of system you choose. When making this decision, it's important to factor in not just the initial installation cost but also how energy efficient the system is and how much money you'll be saving on energy costs in the long run. Investing in a quality AC system now could save you money in the future.