Orifice Tube Description

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The orifice tube reduces the pressure of the liquid refrigerant and at the same time, it adjusts the amount of the liquid refrigerant supplied to the evaporator to maintain cooling ability.
Two O-rings are installed in the orifice tube. They prevent high-pressure liquid refrigerant from flowing out to the evaporator.
The orifice tube is installed in cooler pipe No. 5.

Fig 1: Identifying Refrigerant Flow Through Orifice Tube
Courtesy of MAZDA MOTORS CORP.