What is the first thing to do when a new system has been assembled (built up), and is ready for testing? (A) A) Pull a vacuum. (B) B) Pressurize with the refrigerant to be used in the system. (C) C) Pressurize with an inert gas and leak check. (D) D) Introduce an initial charge of refrigerant and start the compressor. (D)

Before diving into testing a newly assembled system, the very first step is to ensure it’s airtight. So, the correct move is to pressurize the system with an inert gas and check for leaks. This is crucial because any leaks can compromise system operation and efficiency, leading to costly repairs. Once you confirm everything is tight and leak-free, you can move forward with the next steps, including pulling a vacuum to remove moisture and non-condensables, followed by introducing the refrigerant. This sequential approach ensures smooth testing and operational success!