The refrigerant vapor picks up additional heat as it flows from the evaporator to the compressor. The heat is picked up from the ______.

• A. Suction Line
• B. Liquid Line
• C. Discharge Line
• D. Receiver

Answer: (A)

The heat that warms the refrigerant vapor before it reaches the compressor comes from the suction line as the vapor travels toward the compressor. After leaving the evaporator, the low-pressure, low-temperature vapor flows through the suction line and absorbs heat from the surrounding cabinet and line itself, creating a small amount of superheat before entering the compressor. This helps ensure no liquid refrigerant reaches the compressor, protecting it from damage. The liquid line carries high-pressure liquid, the discharge line carries hot gas away from the compressor, and the receiver stores liquid—none of these are the path where the vapor picks up heat on its way to the compressor.