Air Conditioner Valve

This is the service valve used on split air-conditioning installations, where the indoor and outdoor units are connected on site and the circuit has to be evacuated and charged through the valve itself. The body is brass with a flare connection on the line side, a connection to the unit, and a service port with a cap for the gauge hose.

Two body shapes are produced. ACVS is the straight version, used where the pipe leaves the valve in line with the unit connection; ACVB is the bent version, used where the pipe has to turn immediately - the usual situation at the side of an outdoor unit where there is no room for a bend in the copper. Both are made in 1/4, 3/8, 1/2, 5/8 and 3/4 inch flare sizes, covering the liquid and suction lines of domestic and small commercial splits.

The valve has three working positions: fully front-seated (closed to the line, open to the service port), mid-position (open to both, used while charging), and fully back-seated (open to the line, service port isolated). Getting the sequence right matters - charging through a valve that is not in mid-position is the usual reason a system ends up with air in it.

Selection is by line size: match the valve to the flare size of the interconnecting pipe. The service port accepts a standard 1/4 inch charging hose, and the cap should be refitted with its seal after every service, since a missing cap is a slow leak.

Because these valves live outdoors, check the threads before installation and make the flare with a proper eccentric cone tool; a cracked flare on a service valve is difficult to repair once the system is charged.