What causes an automatic expansion valve to begin to operate?

An automatic expansion valve operates based on changes in evaporator pressure. When the pressure in the evaporator rises, it indicates that the refrigerant is absorbing heat effectively and that the system is reaching its capacity. The automatic expansion valve is designed to regulate the flow of refrigerant entering the evaporator; it responds to this increase in pressure by modulating the valve opening. This allows more refrigerant to flow into the evaporator, ensuring optimal cooling performance and preventing system issues caused by underfeeding or overfeeding the evaporator. Therefore, the rise in evaporator pressure is the primary trigger for the operation of the automatic expansion valve.