The orifice tube has 2 functions, it has a screen filter to trap large particles and it changes the high pressure liquid side into a vapour low pressure. There is a small tube which restricts the flow of freon and when it leaves that tube into the low pressure side it is that change of state which you get the cooling affect from. There are other styles of a/c systems as well that do not have a orifice tube setup.
Cam
licenced technician
Cam
licenced technician