ACDelco GM Original Equipment A/C Evaporator Cores are heat exchangers and are located in the HVAC housing, where they cool and dehumidify the cabin air. Refrigerant is metered into the evaporator by the orifice tube or expansion valve. This original equipment evaporator 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.