The smallest particle of foreign matter in an air-conditioning system contaminates the refrigerant, causing rust, ice, or damage to the compressor. For this reason, all replacement parts are sold in vacuum-sealed containers and should not be opened until they are ready to be installed in the system. If, for any reason, a part has been removed from its container for any length of time, the part must be completely flushed using only recommended flush solvent to remove any dust or moisture that might have accumulated during storage. When the system has been open for any length of time, the entire system must be purged completely and a new accumulator must be installed because the element of the existing unit will have become saturated and unable to remove any moisture from the system once the system is recharged. The following general practices should be observed to ensure chemical stability in the system.