R717 Refrigeration System with Thermosiphon Oil Cooler - Trouble Shooting

[RANGER1]

Pratap,
Initially thinking air in system.
As long as liquid receiver level no higher than 80%
Turn plant off, keep condenser fan & water spray pump going for 1/2 hour.
Isolate compressor discharge stop valve, valve 12 balance line then with hose in water purge aggressively from valve 18 off top of condenser.
You could also purge off top of liquid receiver separately.
You may get liquid ammonia out after awhile as it symphony’s up into condenser.
You may see air bubbles rise to top of water, keep plenty fresh water in bucket, or drum.
You may have to do several times.
Normally a purge valve is welded on top of condenser liquid drain to purge air when running.
Air can be detected by using saturated discharge pressure example 35 deg C 1250kpa.
If liquid drain is colder than that, likely air in system.
Let us know outcome.
Assume fan has good airflow, pump sprays flooding condenser coil with water, liquid receiver is about 1.5 metres from liquid drain to liquid receiver level to allow draining.