Air conditioning cooling system evaporator expansion valve #6 #10 Description: Two ports: #6, #10 (about 15.5mm and 18.5mm outer diameter) O ring equalizer: about 9.5mm female (ID = Inner Diameter; Od = Outer Diameter) The expansion valve is a component in a refrigerant system that regulates the rate of refrigerant flow into the evaporator core by using a variable opening valve, regulated by a remote bulb-controlled evaporator temperature sensor. It is located just before the evaporator and after the receiver-dryer.