What indicates that a refrigeration system may have lost refrigerant?

The presence of bubbles in the sight glass is a key indicator that a refrigeration system may have lost refrigerant. The sight glass allows technicians to visually monitor the state of the refrigerant as it flows through the system. A properly charged system typically shows a clear liquid when the refrigerant is at the correct level. However, if the refrigerant level is low due to a leak, the liquid refrigerant will vaporize more than it should, leading to the formation of bubbles in the sight glass. This visual cue is essential for diagnosing refrigerant loss and initiating further investigation and repairs to restore the system's efficiency and effectiveness.

While increased pressure readings, frost on the evaporator, and loud compressor noises can indicate various issues in a refrigeration system, they do not specifically confirm refrigerant loss the way bubbles in the sight glass can. Increased pressure might suggest overcharging or other issues, frost could indicate inadequate airflow or temperature problems, and loud compressor noises might be related to mechanical issues. Therefore, observing bubbles in the sight glass directly points to low refrigerant levels.