Storage freezer NH3 typical running procedure

Hi all

The situation:
I have a storage freezer compressor that runs well during the day bringing the temperature of the freezer down.However, on some weekends I have noticed that the compressor is off even whilst the liquid and suction valves are energised. The fans are also energised. As well as the LT liquid pump is running. Suction pressure is +230 kpa and is suppose to be around 30 to 70 kpa if i remember correctly.

My question:
1) Would something like the oil or LP/HP safety control or high discharge temperature control prevent it from running? I'm sure but not pretty sure as Im too rushed to look further into it. Maybe ive answered my own question?

2) The discharge seperator and discharge line is cool and sweaty even when running and whilst off. Time to check the check valve?