A motor-driven metering valve positioned by a controller using temperature and pressure sensors.
An EEV uses a stepper motor to position the valve, controlled by a board reading sensors on the evaporator and suction line. It can hold superheat more tightly than a TXV across a wide range of loads, and is common on variable-speed equipment. Diagnosis includes checking the sensors and the controller as well as the refrigerant side; manufacturers publish procedures for driving the valve open or closed during service.
Exam work areas
D · Installing systems and controls F · Maintenance, service and troubleshooting