Whether on multiple zone VAV applications or simply where a VFD has been added to evaporator fan of a single zone system, the APR Control will modulate the capacity of the system to match the changing load. By responding to changes in suction pressure, the APR will reduce system capacity as load on the system is reduced (via zoning or simply a VFD) putting the system in to balance so risks associated with low airflow associated with VAV systems are reduced, if not eliminated.