Orifice tubes expand refrigerant
In car air conditioning, an orifice tube is a tube of specific length and cross-section which expands the refrigerant. Unlike the expansion valve however, orifice tubes are unable to regulate flow rate and superheating.
Parts of an orifice tube
Air conditioning orifice tubes are always linked with an accumulator at the evaporator outlet. Orifice tubes are made up of three main parts:
- A metal tube with a chamfered inlet
- A plastic tube body
- An inlet and outlet filter
If the air conditioning loop is contaminated, the orifice tube becomes clogged and will need to be replaced. The orifice tube must also always be replaced when another important part of the air conditioning circuit is replaced like the compressor, condenser, evaporator or accumulator. Remember to flush the A/C loop before installing a new orifice tube.