ActronAir Reversing Valve 7/8 x 1/2 20kW DSF(S)-20-2203C with Coil reverses refrigerant flow direction to switch between cooling and heating modes on compatible ActronAir R22 split ducted and wall split systems. A failed reversing valve causes the system to operate in one mode only, regardless of wall controller commands. Isolate power and recover all refrigerant before replacing any refrigerant circuit valve components.