Question 90Refrigeration & AC - 1st Asst/Chief

The correct answer is C. The sudden low-pressure created in the crankcase at startup causes the release of refrigerant absorbed within the oil, resulting in oil foaming. This is a common occurrence when starting a refrigeration compressor, as the pressure drop leads to the refrigerant dissolved in the oil to come out of solution, causing the oil to foam. The other options are incorrect because: A) Oil foaming is not inherent only to hermetically sealed units, but can occur in any refrigeration system. B) Crankcase heaters are not the cause of oil foaming, but rather help prevent it. D) While a low oil level can contribute to oil foaming, the primary cause is the pressure drop, not just the agitation of the mechanical components.