GM Genuine Parts HVAC Temperature Valves are designed, engineered, and tested to rigorous standards, and are backed by General Motors. These HVAC temperature valves are mechanical doors or flaps that control the amount of heat directed to the cabin based on the temperature control settings. The temperature valve is positioned by an actuator or cable and controls temperature by proportioning the air flow through and around the heater core. 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).