Good air conditioners can last as long as 15 years if they’re properly maintained, but average air conditioners are expected to develop problems after seven to ten years if they’re neglected. If you want to get the most out of your new system, check your filters monthly and replace them as needed, keep your outdoor unit clean and free of debris, and shade the unit during the hottest parts of the day. By performing a little easy maintenance, you can greatly extend the life of your air conditioner and keep it working at its best.