Non-condensables refer to air, nitrogen, or other gases that become trapped inside a refrigeration system and cannot be turned back into a liquid. These gases take up space in the AC Coil Systems and cause the Compressor to work much harder, leading to high electrical bills and premature failure. The only way to remove non-condensables is through a thorough Evacuation using a high-quality vacuum pump before adding refrigerant. If your ACIq system has high head pressure but isn't cooling well, it may have non-condensables in the line. A technician must recover the refrigerant, re-vacuum the system, and add a fresh Factory Charge to fix the problem. This issue is why the purity of the refrigeration loop is the most important part of an HVAC startup. It is a silent efficiency killer that is entirely preventable with proper tools. It is one of the most common reasons for a "mystery" drop in system performance.