To add refrigerant to the system through the suction service valve, the valve stem must be:

To add refrigerant to the system through the suction service valve, the valve stem must be:

• A. Back Seated
• B. Front Seated
• C. Mid Seated
• D. None of the Above

Answer: (C)

Charging through the suction service valve requires a controlled, partial opening of the valve. The valve stem has three seating positions, and being in the mid-seated position creates just enough clearance for refrigerant to flow into the low-pressure side without fully opening the valve or sealing it shut. This lets you introduce refrigerant gradually, monitor gauges, and avoid sudden pressure changes or flooding the system. The other positions effectively seal off flow, so they aren’t suitable for adding refrigerant.

Charging through the suction service valve requires a controlled, partial opening of the valve. The valve stem has three seating positions, and being in the mid-seated position creates just enough clearance for refrigerant to flow into the low-pressure side without fully opening the valve or sealing it shut. This lets you introduce refrigerant gradually, monitor gauges, and avoid sudden pressure changes or flooding the system.

The other positions effectively seal off flow, so they aren’t suitable for adding refrigerant.