Armstrong Furnace H4TXV03 Thermal Expansion Valve (TXV) is a refrigerant control component designed to regulate refrigerant flow in compatible HVAC systems. It works by sensing evaporator outlet temperature and adjusting refrigerant flow to maintain proper superheat, supporting efficient heat transfer and helping protect the compressor. Designed for use with compatible Armstrong furna... https://www.partshnc.com/h4txv03-armstrong-furnace-r410a-txv-valve-1851365