If chemical washing is not sufficient to thoroughly clean your system, professionals may suggest an aircon overhaul service to your air conditioning system. After checking your unit, a professional will help you and then tell you if your air conditioner needs a major overhaul or just a simple chemical cleaning procedure. Typically, professionals recommend a chemical flush or overhaul at least once a year to keep the air conditioner operating at optimum efficiency. What is done during the overhaul of the air conditioner is the cleaning and dismantling and of its parts. Some parts are repaired or replaced (depending on the damage to your air conditioner).