Slope of AC suction lines away from the evaporator and downward toward the compressor is?

• A. Horizontal
• B. Vertical
• C. 45-degree
• D. None

Answer: (A)

Keeping the suction line between the evaporator and the compressor as level as possible is the recommended approach. This configuration helps maintain a steady, vapor-only flow into the compressor and promotes reliable oil return. When the line slopes downward toward the compressor or at any angle, oil can separate from the refrigerant and collect along the line, reducing lubrication and risking compressor damage. A horizontal run minimizes gravity-driven separation and slugging, supporting consistent suction pressure. Small drainage sloping for condensate is usually acceptable, but the suction path itself should be kept as level as practical.