If the bulb on a Thermal Expansion Valve (TEV) loses its charge, what happens to the TEV?

When the bulb on a Thermal Expansion Valve (TEV) loses its charge, it causes the valve to close further than normal. The bulb is responsible for sensing the temperature of the refrigerant as it enters the evaporator and controlling the flow of refrigerant based on that temperature. If the charge is lost, it fails to accurately sense the temperature and results in a loss of its ability to expand, which leads to a reduction in the amount of refrigerant that can flow into the evaporator.

This situation can create a scenario where there is insufficient refrigerant entering the evaporator, which can lead to reduced cooling capacity and potential damage to the system due to insufficient refrigerant for optimal operation. Therefore, the TEV closing up due to a lost charge effectively restricts the flow of refrigerant, confirming that the correct outcome is that it allows less refrigerant into the evaporator.