Which of the following is NOT a symptom of a hermetic system that is low on refrigerant?

A hermetic system that is low on refrigerant typically presents a range of symptoms indicating insufficient refrigerant levels. Low head pressure and low suction pressure are common indicators. When a system is low on refrigerant, the pressures in both the high-side (head pressure) and low-side (suction pressure) usually drop, leading to low values.

The presence of frost on the evaporator is another symptom indicating low refrigerant levels. This happens because the reduced flow of refrigerant prevents the evaporator from absorbing heat properly, causing the temperature to drop and moisture from the air to freeze on the surface.

High head pressure, in contrast, is usually indicative of excess refrigerant or improper system operation and does not align with the symptoms of a system that is low on refrigerant. Thus, identifying high head pressure as a symptom is incorrect, as it tends to correlate with conditions opposite to low refrigerant.