How does the APR Control protect the system from undersized ductwork?

Undersized ductwork will lead to reduced airflow across the evaporator coil resulting in an extreme suction pressure drop. The APR reduces refrigerant flow to eliminate the chance of coil freezing as a result of low evaporator temperature. The APR Control will protect the refrigeration circuit from ultimately failing. In some situations, correcting the ductwork can be unfeasible even though it will provide a better/correct system. The APR Control will protect the circuit and allow the unit to function within the duct design limitations.