When your air conditioner is on, the last thing you want to hear is the system itself. AC systems have become increasingly quieter over the years, so it's concerning when you hear strange noises coming from your AC unit. Certain noises are normal, even expected. When you turn on your air conditioner for the first time after a season of dormancy, it's normal to hear some rattling as the system warms up; what's not normal is if those noises last.
