What symptom could indicate that the orifices used in the thermostatic expansion valve (TEV) are too small?

A clear liquid line sight glass with a superheat of 15k indicates that the refrigerant is entering the evaporator as a liquid but is experiencing a high superheat before it gets to the evaporator. This elevated superheat can be a symptom of insufficient flow of refrigerant into the evaporator due to orifices in the TEV being too small. When the orifice is too restrictive, it prevents enough refrigerant from entering the evaporator, leading to excessive superheating.

In a properly functioning system, you would expect the refrigerant to be adequately vaporized in the evaporator without excessive superheat. The clear sight glass suggests that while there is liquid refrigerant, it is not effectively evaporating within the evaporator coil, supporting the conclusion that the flow is limited, which aligns with the issue of undersized orifices in the TEV.

Other scenarios include increased refrigerant pressure and condensation on the evaporator, which are often indicative of different issues related to refrigerant flow or system charge. Frost accumulation on the compressor can suggest low refrigerant levels or other problems within the system unrelated to the size of the orifices in the TEV. Thus, the symptoms presented in the question point most directly to