Oil safety switch trip

Faulty switch or oil pressure settings. Note: Never add oil to the system without first confirming that oil has been physically lost. Not simply trapped in the system .check oil levels after a defrost cycle. - Manually check for oil pressure, if correct, check that switch is correct model and has proper setting.

a. If sight glass appears empty

Oil trapped in the system Note: at times, the sight glass may appear empty when actually it is completely full

a. check line sizing and risers for proper sizing to return oil

b. If floats are being used, check for proper setting

b. if sight glass appears normal

Liquid refrigerant in crankcase

a. check for low superheats which can return refrigerant-raise superheat.

b. check for liquid migration during off cycle provide a form of pump down protection.