What is the definition of a plug fan? A plug fan is a type of fan that is used to draw in air from one side of the unit, and then push it out of the other side. It is usually made from metal or plastic, and often contains a motor to power the fan blades. Plug fans are commonly used in various types of mechanical and electrical equipment, such as air conditioners, refrigerators, and air purifiers. The fan typically draws in air from the outside of the unit, and then pushes it through the equipment, allowing for efficient cooling or air circulation. The fan blades are often enclosed in a plug-shaped housing, which helps to protect the blades from dust and other contaminants. Plug fans are also commonly used in computers and other electronic devices, to move air through the system to help keep it cool. This type of fan is typically powered by a small electric motor, and is typically quieter than other types of fans.