The Nordyne 664073R 0.073" Piston is an HVAC refrigerant metering component designed to regulate refrigerant flow within compatible air conditioning and heat pump systems. It operates by allowing a precisely controlled amount of refrigerant to pass through its calibrated opening, helping maintain proper pressure and temperature conditions during the cooling cycle. This replacement par... https://www.partshnc.com/664073r-nordyne-073-piston