Final answer:
Refrigerant migrates to the compressor crankcase because of a difference in pressure between the refrigerant and the oil.
Step-by-step explanation:
In a refrigeration system, the refrigerant migrates to the compressor crankcase because of a difference in pressure between the refrigerant and the oil. When the compressor operates, it creates a low-pressure region in the crankcase, causing the refrigerant to flow from the evaporator coil to the compressor crankcase. This pressure difference allows the refrigerant to circulate through the system and play its role in the refrigeration cycle.