VAV terminal units control airflow to individual zones through a motor-operated damper that modulates the primary airflow to the zone. The damper is typically controlled by a zone thermostat or a building automation system (BAS), which receives input from temperature sensors and occupancy schedules. As the zone load changes, the damper adjusts to increase or decrease airflow, ensuring that the zone is maintained at the desired temperature. In some instances, the VAV terminal unit may also include a heating coil and a small recirculating air fan to provide additional heating or cooling capacity.