Expansion Block/Orifice Tube: Description and Operation

The fixed orifice tube assembly (illustration) provides the required restriction between the high and low-pressure liquid refrigerant. It meters the flow of liquid refrigerant into the evaporator core. Evaporator temperature is controlled by a pressure-operated electric switch that senses the pressure within the evaporator. This switch controls compressor operation as necessary to maintain the evaporator pressure within specified limits.

The fixed orifice tube is located in the liquid line near the condenser and has filter screens located on the inlet and outlet ends of the tube body. The filter screens act as a strainer for the liquid refrigerant following through the fixed orifice opening. 0-rings on the tube body prevent the high-pressure liquid refrigerant from bypassing the orifice. Adjustment or repairs cannot be made to the fixed orifice tube assembly which cannot be removed from the liquid line. The liquid line must be replaced, or an Orifice Tube Replacement Kit (Part No. E5VY-190695-A) installed if replacement of the orifice tube is necessary.