Liquid refrigerant flooding back to a compressor’s crankcase and mixing with the crankcase oil is a compressor’s worst nightmare. This situation, along with refrigerant migration, is the reason why a suction accumulator may be needed on a system.
Refrigerant floodback occurs when liquid refrigerant enters the compressor’s crankcase during the running cycle. Refrigerant floodback will dilute the compressor’s oil with liquid refrigerant, which will cause oil foaming in the crankcase, washing the bearings clean of their lubricating oil. This same phenomenon can also pressurize a compressor’s crankcase, causing leakage around rings, valves, and other compressor parts and passageways.