Genuine Daikin 4015593 Outdoor Expansion Valve Body is the electronic expansion valve body in the outdoor unit that meters refrigerant flow, opening and closing to the position the control board commands. When it sticks or fails, the outdoor unit may lose output, ice up, or stop and start at odd times. A genuine valve body meters flow the way your Daikin expects, holding accurate control — where a non-genuine part can meter wrong and unsettle the system.