After recovering the refrigerant (using the proper equipment according to applicable laws), remove the orifice tube from the evaporator core inlet. This can be quite difficult, especially if it's clogged - the pressure of the system trying to work commonly forces the orifice beyond the detents in the tubing. There are
special tools available to extract the orifice, and there are
replacement tubes available so that the impacted one can simply be cut off with the orifice still inside.
