Yes, air handling units (AHUs) are an integral part of HVAC systems. AHUs are responsible for controlling the temperature, humidity, and air quality of a building by circulating and filtering air. They are typically composed of a fan, filter, and heating and cooling coils, and are used to regulate the air pressure and temperature of a space. AHUs are also used to reduce energy costs by controlling the amount of air that is circulated throughout a building.