ACDelco GM Original Equipment HVAC Temperature Valves are mechanical doors or flaps that control the amount of heat directed to the cabin based on the temperature control settings and are GM-recommended replacements for your vehicle's original components. The temperature valve is positioned by an actuator or cable and controls temperature by proportioning the air flow through and around the heater core. These original equipment HVAC temperature valves have been manufactured to fit your GM vehicle, providing the same performance, durability, and service life you expect from General Motors.