ESCO Air Conditioning Practice Exam 2025 – The All-in-One Guide to Exam Success!

In a hermetic system, low refrigerant levels can lead to various symptoms that indicate an issue, but having frost on the suction line is not one of them. Typically, frost or ice on the suction line is a sign of low refrigerant or airflow issues, but in the case of a low refrigerant condition specifically, the suction line is usually warm because there is insufficient refrigerant to absorb heat effectively through the evaporator coil.

In contrast, high head pressure, low suction pressure, and warm air from vents are all indicators of low refrigerant levels. High head pressure occurs when there's an imbalance in the refrigerant cycle, often caused by insufficient refrigerant returning to the compressor. Low suction pressure indicates that the evaporator is not getting enough refrigerant, leading to lower pressures. Similarly, warm air from vents suggests that the cooling process is compromised due to low refrigerant levels, resulting in inadequate temperature reduction as the air passes over the evaporator coil.

Thus, frost on the suction line stands out as the symptom that does not align with the other signs of a hermetic system being low on refrigerant.