Abstract: A refrigerant expansion device including a body having a flow passage extending therethrough which may pass refrigerant in either direction. A piston is slideably mounted in the flow passage for movement between a first position and a second position in response to the direction of refrigerant flow through the flow passage. The piston has a metering port extending therethrough for metering the flow of refrigerant when the piston is moved to the first position responsive to the flow of refrigerant in one direction through the metering device. The piston also includes at least one flow channel substantially parallel to the metering port for passing a substantially unrestricted flow of refrigerant when the piston is moved away from the first position in the direction of the second position responsive to the flow of refrigerant in the opposite direction. Means are provided for moving the piston, against the flow of refrigerant in the one direction away from the first position.