The receiver/drier removes moisture from the refrigerant in the A/C system using desiccant to keep other components of the system free from moisture. The receiver/drier also contains a filter to trap any contaminants that may harm or clog the system and also acts as a storage container for the oil and refrigerant when the system is not in use. The receiver/drier is recommended to be replaced any time the A/C system is opened as the desiccant can become quickly saturated, and useless, from humidity in the outside air.