Causes for restricted liquid lines or restricted components in the liquid line could be a restricted filter-drier from moisture, dirt, oil, or sludge; restricted TXV screen or orifice; kinked liquid line; restricted liquid line solder joint; or receiver outlet valve (King valve) partially closed off.
Many technicians believe that when any part of the system's high side is restricted or plugged, head pressures will elevate. This simply is not the case, especially on a TXV/receiver system. A restricted liquid line will starve the evaporator of refrigerant, causing low evaporator pressures. With a starved evaporator, the compressor and condenser will also be starved, causing low condensing pressure. Most of the refrigerant will now be stored in the condenser and receiver, simulating a pumped-down system.