The Nordyne 669566R R410A is a 3-ton externally equalized thermal expansion valve (TXV) designed for use in HVAC systems utilizing R410A refrigerant. A TXV is a key component that regulates the flow of refrigerant into the evaporator coil of your air conditioner. By precisely controlling the amount of refrigerant, the TXV ensures optimal cooling performance and efficiency. https://www.partshnc.com/669566r-nordyne-r410a-3ton-exteql-txv