What is one key indicator of a refrigerant leak in a system?

A key indicator of a refrigerant leak in a system is a system pressure drop. When refrigerant escapes from the system, it results in less refrigerant available to maintain pressure, leading to a noticeable drop in system pressure. This drop in pressure can affect the overall efficiency and effectiveness of the cooling cycle, causing the system to underperform or even fail.

Monitoring system pressure is essential for identifying potential issues such as leaks. If the pressure readings are consistently lower than the expected operating range, this is a strong indication that there may be a refrigerant leak that needs to be addressed. Recognizing this early can prevent further damage to the system and ensure that it operates efficiently.

The other choices, while they may relate to HVAC performance, do not specifically indicate a refrigerant leak. Low ambient temperature can affect system performance but is not a direct sign of a leak. Increased humidity levels might suggest inadequate cooling but could be due to other factors such as system design or configuration rather than a refrigerant leak specifically. Increased sub-cooling may actually indicate that the system is functioning properly, as it is typically a sign of efficient heat exchange rather than a sign of a leak.