What condition might indicate that the orifices used in the thermal expansion valve (TEV) are too small?

The condition that indicates the orifices used in the thermal expansion valve (TEV) are too small is represented by having a clear liquid line sight glass while simultaneously experiencing 15k superheat.

In this scenario, the presence of a clear sight glass indicates that the refrigerant is not fully vaporized, suggesting that there is insufficient refrigerant flow due to the small orifices. The sight glass should ideally show some bubbles or a mix of liquid and vapor to confirm that refrigerant is properly boiling and evaporating in the evaporator. A substantial superheat reading, like 15k, means that the refrigerant is vaporizing too far along the circuit, which also signifies that there is a lack of liquid refrigerant entering the evaporator effectively. This combination demonstrates that the small orifice size is limiting proper refrigerant flow and leading to an excessive superheat value, marking this scenario as symptomatic of the issue at hand.

This situation highlights the importance of properly sized orifices in maintaining adequate refrigerant flow for optimal system performance.