Fans are the core components of air conditioning and ventilation systems, enabling air transport, heat exchange, and indoor ventilation. Residential split air conditioners, central air conditioning systems, fresh air systems, and wall-mounted units all rely on fans to drive airflow. Indoor units use cross-flow fans to circulate hot and cold air, while outdoor units use axial fans to dissipate heat. Fresh air units and ventilation ducts, combined with centrifugal fans, achieve indoor-outdoor air exchange, expelling stale air and introducing fresh air. Variable frequency energy-saving fans can automatically adjust speed and airflow according to temperature, operating with low noise and high heat exchange efficiency. They ensure constant indoor temperature comfort while effectively reducing long-term energy consumption, and are widely used in air conditioning and ventilation scenarios in residences, shops, and office buildings.