A/C Evaporator Core Orifice

The A/C evaporator core orifice (19D990) assembly is the restriction creating the dividing point between the high- and low-pressure liquid refrigerant and meters the flow of liquid refrigerant into the A/C evaporator core (19860) . Operation is as follows:

• A/C evaporator core temperature is controlled by sensing the pressure within the A/C evaporator core with a pressure-operated electric switch.
• The A/C cyclic switch (19E561) controls A/C compressor (19703) operation as necessary to maintain the A/C evaporator core pressure within specified limits.
• The A/C evaporator core orifice is located in the condenser to evaporator tube (19835) near the A/C compressor and has a filter screen located on the inlet ends of the tube body.
• The filter screens act as a strainer for the liquid refrigerant flowing through the A/C evaporator core orifice opening.
• O-ring seals on the condenser to evaporator tube prevent the high-pressure liquid refrigerant from bypassing the A/C evaporator core orifice .
• Adjustment or service cannot be made to the A/C evaporator core orifice assembly which cannot be removed from the condenser to evaporator tube .
• The condenser to evaporator tube must be replaced, or an Orifice Tube Replacement Kit (E5VY-19D695-A) or equivalent installed if replacement of the A/C evaporator core orifice is necessary.
• The A/C evaporator core orifice should be replaced whenever an A/C compressor is replaced.
• If the high pressure reading is higher than normal and the suction pressure drops rapidly creating a faster than normal clutch cycle rate, the orifice tube may be restricted and should be replaced. This condition is usually indicated by the compressor having a short ON time and a long OFF time.