I have a problem with a copeland compressor, cutting out on low oil pressure often. i carried out the following tests:-

1) clean sump oil strainer
2) check oil pump pressure ( suction 32psig and oil pump pressure 75psig)
3) check crankcase heater operation which was normal( no liquid feedback)
4) normal oil level on the compressor sight glass (normally half)

compressor have a sentronic oil sensing controller with a sensor connected on the oil pump. i have check the operation of the controller as follows:-

contact on the sensor closes when compressor running ( basically normal oil pressure)

contact opens when compressor stops. if i disconnect the sensor cable the contacts are open and the red indicator on the controller lights up indicating low oil pressure and once reconnected with 120 secs the green light ups ( normal oil pressure).

compressor stops if the leave cables disconnected for more than 120 secs. So basically i have tested everything but problem keeps coming often.

plz help.