What indicates the presence of air in a low-pressure system?

In the context of refrigeration systems, the presence of air in a low-pressure system is indicated by high head pressure. Air does not condense in the same way that refrigerants do, which causes the compressor to work harder to maintain system pressure. This results in an increase in head pressure since the compressor is attempting to compress the non-condensable gases, which can lead to inefficient operation and potential damage to the system.

High head pressure can lead to issues such as reduced system efficiency, overheating, and even compressor failure if left unaddressed. Maintaining the correct refrigerant charge and ensuring that air and other non-condensables are removed from the system is crucial for optimal performance and longevity of the equipment.