Expansion Block/Orifice Tube: Description and Operation

A/C Evaporator Core Orifice

The A/C evaporator core orifice is located in the inlet tube and has filter screens on the inlet and outlet ends of the tube body. The filter screens act as strainers for the liquid refrigerant flowing through the fixed orifice opening. O-rings, on the tube body, prevent the high pressure liquid refrigerant from bypassing the orifice. Adjustment or repairs cannot be made to the A/C evaporator core orifice and it must be replaced as a unit.

The A/C evaporator core orifice is a restriction between the high and low pressure refrigerant and meters the flow of liquid refrigerant into the A/C evaporator core. Temperature is controlled by sensing the pressure within the A/C evaporator core with an A/C cycling switch. The A/C cycling switch cycles the A/C compressor on or off as necessary to maintain the pressure within specified limits.

NOTE: Service replacement includes O-rings. Replacement O-rings available from Motorcraft only.