Mini-split systems should be serviced on the same schedule as central HVAC systems. The twice-yearly servicing helps to keep the system running smoothly and the interior air quality high. When a mini-split system isn't cleaned for an extended period of time, the risk of premature component wear, mold growth, and the formation of unusual odors grows dramatically. Furthermore, extra dirt, dust, or mold in your mini-split system can lower air quality in your house by cycling pollutants into your living area.