The plastic expansion (orifice) tube includes the following components:

The expansion (orifice) tube is located in the evaporator inlet pipe at the liquid line connection. The tube restricts the high pressure liquid refrigerant in the liquid line. The tube meters the refrigerant flow to the evaporator as a low pressure liquid.

The expansion tube and the orifice have filter screens. The filter screens which protect the tube from contamination on both the inlet and the outlet sides.

The refrigerant in the system flows from the high pressure side of the tube to the low pressure side when the following conditions exist:

The refrigerant will flow until the pressure is equalized. You may hear a faint hissing sound for 30-60 seconds. This sound is normal.