Orifice tubes are located in the inlet tube of the evaporator between the outlet of the condenser and the inlet of the evaporator. Anorifice tube
is usually 7 to 8cm in length and comprises of a small brass tube surrounded by plastic with covering filters at either end.
The main problem that can occur with orifice tubes is that they can become clogged with small debris. Replaced orifice tubes with high quality ones which are easily available at Eurocarparts.com