After passing the leak test, the system should be ______ prior to being charged.

• A. Inspected
• B. Recharged
• C. Evacuated
• D. Pressurized

Answer: (C)

After passing the leak test, the system should be evacuated prior to charging. Evacuation uses a vacuum pump to pull out air and moisture from the system. This is crucial because air and water vapor can cause problems: non-condensable gases raise system pressure and reduce heat transfer efficiency, moisture can form acids or ice, and trapped gases or moisture can skew the refrigerant charge and lead to corrosion or other failures. By pulling a deep vacuum and then confirming the system holds that vacuum, you ensure a dry, clean environment for the charge. The other steps aren’t performed before charging: inspecting afterward, recharging, or simply pressurizing don’t remove moisture or non-condensable gases, which is why evacuation is the proper preceding step.