Expansion Block/Orifice Tube: Description and Operation

Expansion ( Orifice ) Tube:

The plastic tube, with its mesh screen and orifice, is located in the evaporator inlet pipe at the liquid line connection. It provides a restriction to the high pressure liquid refrigerant in the liquid line, metering the flow of refrigerant to the evaporator as a low pressure liquid. The orifice tube is protected from contamination by filter screens on both inlet and outlet sides. The tube may be cleaned of any metal particles that collect on the screens or the tube should be replaced. No repairs can be made to the orifice tube.