TUBE-A/C VARIABLE ORIFICE

The A/C orifice tube establishes the pressure differential between the high and low pressure sides of the A/C system by providing a restriction between the A/C condenser and the A/C evaporator. The A/C orifice tube in this vehicle is installed in the A/C liquid line and is of a variable orifice valve (VOV) design.

The variable A/C orifice tube consists of the inlet filter screen (5), the bi-metal coil (4), the fixed port (3), the variable port (6), metering orifices (1), a nylon mesh diffuser screen (7) and two rubber O-rings (2) which seal the tube to the inside of the A/C liquid line to prevent refrigerant from bypassing the metering orifices.

OPERATION

The variable A/C orifice tube provides improved A/C system cooling during city driving and when under heavy loads by controlling refrigerant flow through the two parallel flow paths integral to the orifice tube. Under normal loads, the refrigerant flows through the inlet filter screen, the fixed and variable ports and both metering orifices. As the load on the A/C system increases, the temperature of the refrigerant leaving the A/C condenser increases, which causes the bi-metal coil to expand and restrict the flow of refrigerant through the variable port of the tube. Restricting the flow of refrigerant through the variable port and its orifice provides a greater pressure differential between the high and low pressure sides of the A/C system, resulting in colder refrigerant vapor traveling through the A/C evaporator to help remove the heat from the conditioned air flowing into the passenger compartment.