Orifice Tube System
Orifice tube air conditioning systems regulate refrigerant flow to the evaporator using a fixed metering device (orifice tube).
Expansion Valve System
In an expansion valve air conditioning system, refrigerant flow to the evaporator varies according to the pressure in the suction line (evaporator outlet). This is detected within the expansion valve or by a sensing bulb mounted on the line and relayed to the expansion valve via a capillary tube.