When checking refrigerant levels, what is a common sign of undercharging?

A common sign of undercharging in a refrigeration system is lower than normal pressures. When the system lacks sufficient refrigerant, it cannot maintain the appropriate pressure levels. This is because the refrigerant is responsible for absorbing heat from the indoor air and releasing it outside. When there is insufficient refrigerant, the pressure drops as the system struggles to circulate the limited amount available.

By measuring the pressures in the system, technicians can identify that they are below the expected operational range, which confirms that the refrigerant charge is inadequate.

The other options present different symptoms associated with other issues. For instance, increased cooling efficiency typically indicates that a system is functioning well, not that it is undercharged. Similarly, frost forming on the evaporator coil is often a sign of overcharging or restricted airflow rather than undercharging. Higher than normal pressures usually suggest that too much refrigerant is present or that the system is experiencing a blockage, which again links to conditions other than undercharging. Thus, recognizing lower than normal pressures is crucial for diagnosing an undercharged refrigeration system effectively.