The liquid line in a refrigeration system begins at the outlet of the receiver and includes the filter drier, sight glass, metering device, and any other components located between the receiver and TXV. The filter drier is a very likely component to become restricted from moisture and/or debris accumulation because it is designed to absorb and store debris and moisture. A restricted filter drier will give the same symptoms as a restricted TXV since it, too, is in the liquid line.