Service technicians must be able to distinguish between a restricted liquid line and a system overcharge. Adding refrigerant to a system that has a restriction before the receiver can lead to a dangerous high-pressure situation, especially if the high-pressure control is not set or is not operating properly.
When a restriction occurs before the receiver in a low-temp commercial refrigeration system, the evaporator and compressor will be starved. Any refrigerant that does enter the condenser will be trapped there, causing high condenser subcooling.