ACDelco GM Original Equipment A/C Orifice Tubes, which separate the high and low pressure sides of the air conditioning system, control the flow of low pressure liquid refrigerant into the evaporator. The orifice tube is essentially a calibrated restriction located at the inlet to the evaporator. This causes the necessary pressure drop to allow the liquid refrigerant to evaporate within the evaporator and absorb heat. Since the orifice tube is fixed, the system is regulated by either cycling the compressor clutch or by a variable displacement compressor. This original equipment orifice tube 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.