xpansion valves are devices used to control the refrigerant flow in a refrigeration system. They help to facilitate the change of higher pressure of liquid refrigerant in the condensing unit to lower pressure gas refrigerant in the evaporator.

The term “low side” is used to indicate the part of the system that operates under low pressure, in this case the evaporator. The “high side” is used to indicate the part of the system that operates under high pressure, in this case the condenser.

Manualexpansion valve  It is the type that requires a person to control the valve to open more or less. The refrigerant flow rate also depends on the pressure difference between the high pressure and low pressure side of the system.