A HVAC unit is a type of mechanical system that is used to regulate the temperature, humidity, and air quality of a given space. It is composed of a variety of components, including an air handler, evaporator coil, condenser coil, compressor, and air filter. The air handler circulates air throughout the space, while the evaporator coil absorbs heat from the air and transfers it to the refrigerant. The condenser coil then releases the heat to the outside environment. The compressor pumps the refrigerant between the evaporator and condenser coils, and the air filter removes dust and other airborne particles from the air. HVAC units are used in both residential and commercial settings to provide a comfortable environment for occupants. They are also used to improve indoor air quality by removing pollutants and allergens from the air.