An orifice tube in a properly functioning system can be found by locating the area between the outlet of the condenser and the inlet of the evaporator that suddenly makes the change from hot to cold. In many cases you should see small indentions or dimples placed in the line that keep the orifice tube from moving.

Some Ford models have a permanently affixed orifice tube built within the liquid line. To replace the orifice tube you'll need to replace the entire line. If a replacement liquid line is not available, and back-flushing the line is not acceptable, the orifice can be cut out of the line with a tubing cutter and replaced with a combination filter/orifice assembly or a field repair kit, as shown below.

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