In diagnosing a leak in a hermetic system, which of the following is a common early sign to check?

• A. Hissing at joints
• B. Frost around connections
• C. Traces of oil
• D. Excessive noise

Answer: (C)

In a hermetic system, leaks are often first signaled by the oil that circulates with the refrigerant. When a leak begins, some of that oil escapes with the refrigerant and can leave visible traces around joints, fittings, or along the lines. Those oil traces are one of the most direct and early indicators that refrigerant is leaking, appearing before other symptoms like frost or unusual noise develop. Frost around connections happens when refrigerant is extremely cold at the surface and moisture freezes, which may occur later or only if enough refrigerant has leaked and the surface conditions align. Excessive noise points to mechanical issues rather than a leak path, and hissing can occur for various reasons, not always indicating an early leak. So, spotting traces of oil is the best early check for a leak.