Fresh Air Dehumidifier incorporates a fresh air damper, return air damper, HEPA filter, and a five-in-one air sensor. It can automatically control the indoor fresh air intake and dehumidification based on the indoor air quality and dehumidification requirements. It offers four modes: dehumidification mode, fresh air mode, hybrid mode, and auto mode, catering to the different needs of fresh air and dehumidification throughout the seasons.