The function of a suction line filter drier is to capture and retain system contaminants, moisture and harmful acids in order to protect system components.The by-pass valve start to work when refrigerant is flowing in the direction of the arrow on the filter drier label. If excessive pressure drop produced when refrigerant flow through the filter drier, the by-pass valve will open slightly to keep enough airflow and make the hermetic compressor motor get proper cooling. the by-pass valve will be ineffective if the suction line filter drier is installed to reverse flow, thus an acces valve is required to measure the pressure drop from core to compressor’s suction valve.
