environment that surrounds the line 26 as measured by sensor 42 and or the temperature of the liquid refrigerant entering the evaporator 20 as measured by evaporator inlet sensor 44 modulating the flow of refrigerant allows the system 10 to efficiently cool the refrigeration cases 18 to a desired temperature while preventing line sweating in line 26 connected to the evaporator 20 in order to prevent line sweating in a refrigeration system the temperature of the liquid refrigerant running through the line 26 to the evaporator 20 must be kept above the dew point temperature in the store when the dew point temperature is high as a result of high humidity the temperature of the liquid refrigerant must be kept relatively high to prevent line sweating in prior art systems the temperature of the liquid refrigerant was constant and therefore had to be set for a high dew point in order to prevent line sweating under high humidity as a result the prior art refrigeration systems avoided line sweating but were inefficient on lower humidity days or undesirable sweating occurred on higher humidity days ideally the temperature of the liquid refrigerant should be as low as possible without dipping below the dew point temperature the modulating valve 40 of the present invention operates to adjust the temperature of the liquid refrigerant entering the evaporator 20 when the humidity is relatively high the controller 40 u2032 throttles toward a closed position which.