Air filtration in a mini-split involves multi-stage filters that remove dust, allergens, and odors from the indoor air. The MRCOOL Olympus 4th Gen Wall AH 9,000 BTU features easy-to-clean filters. These filters are essential for maintaining indoor air quality in every Multi-Zone installation. Regular cleaning of these filters ensures maximum airflow and efficiency. Some units even offer carbon or ionic filters for deeper purification. Good filtration is a key benefit of choosing a modern ductless system.