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

When a thermal expansion valve (TEV) or capillary tube is used as a metering device, a low refrigerant charge typically leads to equal head pressure. This is because the metering device is designed to maintain a balance between the refrigerant flow and the pressure in the system.

In a refrigeration system, head pressure refers to the pressure in the high side of the system, which is crucial for maintaining proper operation. A low charge of refrigerant can reduce the amount of refrigerant that is available to absorb heat and can affect the pressure differentials throughout the system. If the charge is insufficient, the metering device cannot adequately regulate the refrigerant flow, leading to the pressures in the system stabilizing at a level that might seem equal, rather than being overly high or low.

The system's overall performance will suffer with low refrigerant charge, as it may not be able to achieve the desired temperature and efficiency, but from a head pressure perspective during steady-state conditions, it may lead to pressures that appear equal across the system.

This understanding helps clarify why a low refrigerant charge would be associated with equal head pressure rather than other options like high or variable head pressure, which would typically indicate either an excessive charge or fluctuations in the