Unbalanced system, load in excess of design conditions.
Compressor discharge valve leaking.
Leaking hot gas defrost solenoid/hot gas bypass valve.
Hot gas bypass regulator piped direct to suction, without a liquid injection TEV.
Balance system components for the necessary load requirements.
Repair or replace valve.
Check and replace hot gas bypass valves if required.
Install properly sized ALCO LCL liquid injection thermo valve.