Expansion Block/Orifice Tube: Description and Operation

A/C VARIABLE ORIFICE TUBE

Variable Orifice Valve - 2.0L LHD Models:

A variable orifice valve (VOV) is factory installed in the liquid line between the outlet of the condenser and the inlet of the evaporator. The VOV is located in the end of the liquid line that is closest to the condenser. The inlet end of the VOV has a nylon mesh filter screen, which filters the refrigerant and helps to reduce the potential for blockage of the metering orifices by refrigerant system contaminants. The outlet end of the tube has a nylon mesh diffuser screen. The O-rings on the plastic body of the VOV seal the tube to the inside of the liquid line and prevent refrigerant from bypassing the metering orifices.

The variable orifice valve (VOV) is used to meter the flow of liquid refrigerant into the evaporator coil. The high-pressure liquid refrigerant from the condenser expands into a low-pressure liquid as it passes through the metering orifices and diffuser screen of the VOV There are two parallel flow paths integral to the VOV, a fixed port and a variable port. As the temperature of the refrigerant increases, the bimetal coil moves the variable port to the closed position. High temperature results in more restriction, and lower temperature results in less restriction. This design improves A/C cooling at high loads and or city traffic.

The VOV is not serviceable. It cannot be repaired, and if faulty or plugged, it must be replaced as part of the liquid line.