If your air conditioner is more than 15 years old, it is probably reaching the end of its lifespan. If you have been properly maintaining your system with annual tune-ups, this lifespan could stretch as far as 15-20 years (which is why we always recommend routine maintenance!) We also recommend replacing your AC system if it requires frequent repairs, if it is no longer keeping your home comfortable, or if you notice that your utility bills are higher than normal.