The APR control converts a direct expansion system into a modulating direct expansion system. This means that system capacity will vary to match changing load conditions. System load compliance is achieved.

In addition to capacity modulation, the APR Control maintains the evaporator coil in a dehumidifying mode, while modulating system capacity. As a result, the APR Control enhanced system maintains constant temperature with excellent latent heat removal and lower overall humidity levels, according to the manufacturer.

At the same time, the APR Control maintains the system in a continuous dehumidifying mode. The air conditioning or heat pump system with the APR Control drives the system into a constant temperature mode and stabilizes the humidity level to the ability of the evaporator coil to remove latent heat. Coil row depth and fins per inch construction determine the bypass factor, which controls the effectiveness of the dehumidifying mode during partial load conditions. The APR Control is controlled by the enthalpy (sensible heat plus latent heat), or the total heat of the air.