Expansion Block/Orifice Tube: Description and Operation

The plastic expansion (orifice) tube, with its mesh screen and orifice, is located between the condenser outlet and evaporator inlet. 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 expansion (orifice) tube and orifice are protected from contamination by filter screens on both inlet (1) and outlet (3) sides.

When system diagnostics indicate a restricted expansion (orifice) tube, it may not be necessary to replace the tube. Metal chips, flakes, or slivers found on the screen may be removed with compressed air and the expansion (orifice) tube may be reused if:

- The plastic frame is not broken.
- The brass expansion (orifice) tube is not damaged or plugged.
- The screen material is not torn.
- The screen is not plugged with fine gritty material.