Receiver driers can be mounted on condensers or on their own. They act as filters and are very important in the air-conditioning system. As the liquid refrigerant comes out of the condenser it enters the receiver drier. While the liquid refrigerant is in the receiver drier, it is simultaneously filtered to remove any impurities or humidity that may be present. The receiver drier works as a filter to keep the refrigerant from becoming too dirty or saturated, so that no harm is caused to the air-conditioning system.