A crankcase heater is often used to prevent refrigerant from mixing with compressor oil during what conditions?

• A. High ambient temperature
• B. Low ambient temperature
• C. Normal operation
• D. System shutdown

Answer: (B)

A crankcase heater is employed to prevent refrigerant from mixing with compressor oil primarily during low ambient temperature conditions. When the temperature is low, the refrigerant can condense and settle in the compressor's crankcase. This can lead to the refrigerant dissolving in the oil, which can create mixing issues that may affect the lubricating properties of the oil and the efficiency of the compressor.

The crankcase heater works by maintaining the oil at a higher temperature, thereby keeping the refrigerant in a gaseous state. This is critical for proper compressor function and ultimately helps to ensure that the oil remains effective for lubrication. By keeping the oil warmer, the heater prevents the refrigerant from gathering in the crankcase, thus maintaining a clear separation between the refrigerant and the oil during these low temperature situations. This is essential for protecting the compressor and ensuring reliable operation during startup after periods of inactivity.