The tubing that carries heat-laden refrigerant gas from the evaporator to the compressor is the

• A. Suction line
• B. Discharge line
• C. Liquid line
• D. Capillary tube

Answer: (A)

In a vapor-compression refrigeration cycle, the gas that comes off the evaporator has absorbed heat and is at relatively low pressure. That heat-laden refrigerant gas is drawn back to the compressor through the suction line. This line is the path for low-pressure, gaseous refrigerant returning to be compressed. The other lines serve different roles: the discharge line carries high-pressure gas from the compressor to the condenser; the liquid line transports high-pressure liquid from the condenser to the expansion device; and the capillary tube acts as a throttling device for some systems. Thus, the tubing described is the suction line.