If a refrigeration packing nut on a service valve is leaking, the correct action is to

• A. Loosen the packing nut
• B. Tighten the packing nut
• C. Replace the packing nut
• D. Apply sealant to threads

Answer: (B)

A service valve packing leak is addressed by increasing compression on the stem packing. Tightening the packing nut applies more pressure to the packing material, which seals around the valve stem and stops the leak. This is the designed first-step adjustment for leaks at the packing gland. If the leak persists after a small, careful tightening, you can continue to tighten in small increments, but you must avoid over-tightening that could damage the packing or the stem. Replacing the packing nut isn’t typically required for a simple leak unless the nut itself is damaged, and applying sealant to threads is not appropriate here because it can contaminate refrigerant and doesn’t effectively seal the packing around the stem. Loosening would worsen the leak by reducing compression on the packing.