ACDelco GM Original Equipment A/C System Valve Cores are components of the A/C service valve through which your vehicle's refrigerant can be accessed and serviced. The valve core is a spring-loaded poppet valve that is opened when the service technician connects the A/C service machine hose couplers. This original equipment valve core is a GM-recommended replacement for your vehicle's original components and has been manufactured to fit your GM vehicle, providing the same performance, durability, and service life you expect from General Motors.