Sab 128 Problems

[RANGER1]

Marthe,
Suction, discharge, oil pressures, refrigerant etc would be helpful.
Are pressures normal/ abnormal?
These types of compressors have hydraulically driven suction check valves, so oil pressure & filter condition important.
Also slide valve indication may be out of calibration, as MBC mentions, can you force it to load more?
Is something inhibiting it from loading like motor amps or pressure, check settings.

Check if your readings are correct for transmitters as bad power supply can upset readings as well.

http://www.cooltech.ru/en/spares/sabroe/spiral/sab128