The drying filter is between the condenser and the expansion valve.
Its function is to store, filter solid dirt, bind moisture, and dissociate gas. The refrigerant passes fluid through the filter. Moisture can flow through the hose walls and the compressor shaft seal. Moisture may also cause the expansion valve to freeze causing the system to fail. The drier filter must be installed according to the diving tube design, according to the flow of the refrigerant. Therefore, an arrow on the outer housing shows the flow direction. The drying filter can be either standing, lying or in the condenser side swappable insert version.