Which of the listed statements describes the reason why oil foaming occurs when starting a refrigeration compressor?

Correct Answer: Option C — This condition is the result of the sudden low-pressure created in the crankcase at start up causing the release of refrigerant absorbed within the oil.

Refrigerant vapor dissolves readily in compressor lubricating oil under high pressure and low temperature. A sudden drop in crankcase pressure during startup causes this dissolved refrigerant to rapidly boil out, creating violent oil foaming.