A thermostatic expansion valve (TXV) is a crucial component in refrigeration and air conditioning systems. It regulates the flow of refrigerant into the evaporator coil based on the temperature of the refrigerant. By adjusting the flow, the TXV ensures that the evaporator operates efficiently, preventing both underfeeding and overfeeding of refrigerant. The TXV contains a sensing bulb that monitors the temperature of the refrigerant vapor leaving the evaporator. When the temperature rises, the valve opens wider to allow more refrigerant in, and when it drops, the valve closes to reduce the flow. This precise control helps maintain optimal system performance and energy efficiency.