Liquid Line Restriction

Probable Cause: Remedy:
Partially plugged liquid line filter-drier.Check the temperature of the drier at the inlet and outlet. If the temperature at the inlet is warmer than outlet, the drier is restricted.

  • This means the drier has done its job. It has retained so much contamination, that the high pressure drop thru the drier is causing the liquid inside the drier to flash.
Replace the liquid line filter-drier with an ALCO EK-Plus or STAS core drier.
If the moisture indicator shows wet refrigerant, it means the drier is saturated with moisture and can’t remove any more.

  • Excessive moisture can cause ice formation at the TEV’s port (if operating below 32°F), resulting in liquid restriction, i.e. starving the evaporator.
 A moisture saturated filter-drier has little effect on increased pressure drop across the shell.
Liquid line solenoid not operating properly or undersized.

  • Excessive pressure drop across the valve will cause flash gas.
Repair or replace with a correctly sized ALCO solenoid valve, and install in the proper direction of refrigerant flow.
Crimped liquid line.

  • This will cause excessive pressure drop- flash gas
Replace the damaged section.
Field installed service valve at liquid receiver, hand valve might be too small or not fully open. Pipe joint in liquid line partially filled with solder. Make sure all valves are fully open, correctly sized, and internally clean.