Which statement about the crankcase heater is true?

• A. It boils off liquid refrigerant trapped in the oil
• B. It warms the room
• C. It increases refrigerant charge
• D. It prevents refrigerant leaks

Answer: (A)

The crankcase heater’s job is to keep the compressor crankcase warm to prevent liquid refrigerant from accumulating in the oil and causing slugging on startup. By warming the oil, any refrigerant that has migrated into it is kept in vapor form or boiled off, which protects lubrication and helps the compressor start reliably.

That’s why the statement about boiling off liquid refrigerant trapped in the oil is the best one. The heater is not used to heat a room, it doesn’t increase the refrigerant charge, and it doesn’t stop leaks.