Overloaded refrigerant unit.
Discharge the refrigerant out at maximum speed, to a place on the unit where there is only gas. In the case of an airtight system without registers, use a perforation register applied to the compressor service tube. Measure the load using the liquid drawer instructions. If this is not installed, the same type of lifting can be done using an ultrasound liquid flow indicator, temporarily applied at the beginning of the liquid line.