usually an axial piston pump compressor, and is compressed to a higher pressure, resulting in a higher temperature as well. The hot, compressed refrigerant vapor is now at a temperature and pressure at which it can be condensed and is routed through a condenser, usually in front of the car's radiator. Here the refrigerant is cooled by air flowing across the condenser coils (originating from the vehicle's movement or from a fan, often the same fan of the cooling radiator if the condenser is mounted on it, automatically turned on when the vehicle is stationary or moving at low speeds) and condensed into a liquid. Thus, the circulating refrigerant ejects heat from the system and the heat is carried away by the air. In a thermal expansion valve air conditioning system, the condensed and pressurized liquid refrigerant is next routed through the receiver-drier, that is, a one-way desiccant and filter cartridge that both dehydrates the refrigerant and compressor lubricant oil mixture to remove any residual water content (which would become ice inside the expansion valve and therefore clog it) that the vacuum done prior to the charging process did not manage to remove from the system, and filters it to remove any solid particles carried by the mixture, in addition to acting as a storage vessel for any excess liquid refrigerant during low cooling demand periods, and then through the thermal expansion valve where it undergoes an abrupt reduction in pressure. That pressure reduction results in flash evaporation of a part of the liquid refrigerant, lowering its temperature. The cold refrigerant is then routed through the evaporator coil in the passenger compartment. When the expansion device is a simple fixed metering orifice, known as an orifice tube, the receiver-drier is instead located between the evaporator outlet and the compressor, and in this case, it is known as an accumulator. In such an air conditioning system, the accumulator also prevents the liquid refrigerant from reaching the compressor during low cooling demand periods. The air, often after being filtered by a cabin air filter, is blown by an adjustable speed electric powered centrifugal fan across the evaporator, causing the liquid part of the cold refrigerant mixture to evaporate as well, further lowering the temperature. The warm air is therefore cooled, and also deprived of any humidity (which condenses on the evaporator coils and is drained outside of the vehicle) in the process.