Genuine Daikin 1838967 Outdoor Gas Stop Valve Assembly is the gas-line stop valve in the outdoor unit that isolates the refrigerant circuit at the gas service port for installation and servicing. When it leaks or seizes, the unit can lose refrigerant, lose output, or be hard to service safely. A genuine valve seals and operates the way your Daikin expects — where a non-genuine part can leak or seize.