If refrigerant is to be added to a system, the refrigerant cylinder is usually connected to the

• A. Center port of gauge manifold
• B. Right-handed port of the manifold gauge
• C. Left-handed port of the manifold gauge
• D. Discharge service valve of the compressor

Answer: (A)

The center port on a three-port gauge manifold is the charging port. When you add refrigerant, you connect the refrigerant cylinder to this center port because it’s designed to accept the charging hose and allow controlled flow into the system. The manifold valves let you meter the refrigerant and monitor pressures while the center port provides a direct path into the system’s low-pressure side. The other two ports connect to the low- and high-pressure service lines for measurement and recovery, not for attaching the refrigerant cylinder. The discharge valve at the compressor is not used for adding refrigerant.