What symptom indicates a restriction in a metering device?

A restriction in a metering device can lead to high superheat readings. This occurs because the refrigerant is not being allowed to flow properly through the system. If there is a restriction, the evaporator does not receive enough refrigerant to absorb the necessary heat from the surrounding air or water. As a result, the refrigerant that does manage to enter the evaporator may vaporize completely before it absorbs sufficient heat, leading to a higher temperature of the refrigerant upon exiting the evaporator.

This high superheat indicates that the refrigerant is overheating because it is not being adequately fed into the evaporator, a direct consequence of the restriction affecting the intended operation of the HVAC system. In contrast, low superheat or excessive subcooling often signify other issues, such as overfeeding of refrigerant or improper system charge, and high-temperature readings are generally more indicative of system efficiency issues rather than a direct symptom of a metering device restriction.