After repair is completed, the system should be ________ tested again for leaks.

• A. Pressure
• B. Temperature
• C. Vacuum
• D. Flow

Answer: (A)

When verifying a repair, the goal is to ensure the system won’t leak under operating conditions. The most direct way to do this is a pressure test: seal the system, pressurize it with an inert gas to a specified test pressure, and watch for any pressure drop over a set period. If the pressure remains stable, joints and braze/seal points are sound; any drop indicates a leak that needs fixing.

Temperature testing isn’t reliable for revealing leaks because ambient conditions can mask issues. Vacuum testing is useful during evacuation to remove moisture and can show leaks if the system cannot hold a vacuum, but it doesn’t simulate normal operating pressure as effectively as a pressure test. Flow testing checks whether gas or refrigerant moves through the system, not whether a leak exists.

So, pressure testing is the best choice for confirming the system is leak-free after repair.