What are common symptoms of a hermetic system that is low on refrigerant?

When evaluating a hermetic system that is low on refrigerant, several symptoms can be indicative of this issue. The correct choice highlights the combination of lower than normal head pressure, lower than normal suction pressure, and frost on the evaporator, which are all key indicators of low refrigerant levels.

When the refrigerant is insufficient, the pressures within the system drop because there is not enough refrigerant to absorb heat effectively. This leads to lower head pressure—indicating that the system's compressor is not working under normal load—as there isn't enough refrigerant to maintain the pressure necessary for proper operation. Additionally, the lower suction pressure reflects this same issue; the evaporator isn’t able to maintain the proper flow and pressure of refrigerant, resulting in reduced cooling capacity.

Furthermore, the presence of frost on the evaporator coil occurs because the low refrigerant levels prevent adequate heat absorption. Instead of circulating efficiently and maintaining the proper temperature, the evaporator coil can drop below freezing point as refrigerant levels dwindle, leading to frost build-up.

Recognizing these symptoms is critical for HVAC technicians to diagnose and address refrigerant issues promptly, ensuring that systems operate efficiently and prevent further damage.