GM Genuine Parts A/C Expansion Valves are designed, engineered, and tested to rigorous standards, and are backed by General Motors. These A/C expansion valves are metering devices that control the flow of refrigerant into the evaporator. The expansion valve meters the flow of liquid refrigerant based on the evaporator core temperature, keeping it just above freezing. GM Genuine Parts are the true OE parts installed during the production of or validated by General Motors for GM vehicles. Some GM Genuine Parts may have formerly appeared as ACDelco GM Original Equipment (OE).