The unit has multiple functions such as refrigeration, heating, dehumidification, constant temperature and humidity, which can be set freely and automatically adjusted; The unit adopts heat pump heating, which has high heating capacity and low energy consumption; The unit adopts a variable frequency compressor, which has high energy efficiency and only supplies cold and heat as needed, avoiding frequent on-off of the compressor. The outlet temperature is stable and the comfort is better; The unit controls the outlet air temperature by adjusting the condensation heat during freezing and dehumidification, eliminating the working mode of turning on electric heating and temperature regulation during dehumidification of general constant temperature and humidity machines, and making the system run more energy-efficient; The unit is equipped with auxiliary electric heating, which can effectively ensure heating effect in extreme low temperature weather; Equipped with fresh air function, the fresh air volume can be adjusted, and the exhaust enters the outdoor heat exchanger to improve the energy efficiency of the unit; The core components such as compressors are made of internationally renowned brand products, which are stable, reliable, and durable; Adopting a microcomputer automatic control system, the operation is simple and the temperature control accuracy is high. Application field: Archives