A split air conditioner has a cabinet with a fan and evaporator for mounting within a structure. The cabinet includes one or more movable dampers or movable filters positioned in the flow path between the air inlet and the outlet for selectively filtering contaminants from the air to provide a greater or lesser degree of filtration of the air. The movable filters include sliding and/or pivot mounting structure which may accommodate stacking multiple filters with different filtering characteristics. The system may operate in a filtering only mode with no cooling, a cooling only mode with no filtering, or a combination of cooling and selective filtering.