Expansion Block/Orifice Tube: Description and Operation

NOTE: The A/C evaporator core orifice should be replaced whenever an A/C compressor is replaced.







The A/C evaporator core orifice has the following characteristics:
- is color-coded orange
- has a diameter of 1.46 mm (0.058 inch)
- is located in the condenser to evaporator tube
- has filter screens located on the inlet and outlet ends of the tube body

The A/C evaporator core orifice is the restriction in the refrigerant circuit that creates the pressure drop necessary for cooling by metering the flow of liquid refrigerant into the A/C evaporator core, which reduces the pressure.

Operation is as follows:
- The inlet filter screen acts as a strainer for the liquid refrigerant flowing through the A/C evaporator core orifice.
- O-rings on the A/C evaporator core orifice prevent the high-pressure liquid refrigerant from bypassing the A/C evaporator core orifice.
- Adjustment or services cannot be made to the A/C evaporator core orifice assembly. It must be replaced as a unit.