Which scenario best describes the use of a crankcase heater?

• A. To prevent mixing of refrigerant and oil during low ambient temperature
• B. To prevent mixing of refrigerant and oil during high ambient temperature
• C. To eliminate non-condensables
• D. To reduce discharge pressure

Answer: (A)

Crankcase heaters keep the compressor crankcase warm so refrigerant does not condense in the oil when temperatures are cold. At low ambient temperatures, refrigerant can migrate into the crankcase and mix with the oil, which can dilute lubrication and lead to damage when the compressor starts. Heating the crankcase prevents this condensation and keeps lubrication reliable during cold conditions. It isn’t used to eliminate non-condensables or to reduce discharge pressure, which are addressed by other parts of the system.