the new dan foss valves 1/4 to 1/2 ton sweat have a very small orifice, if your system is dirty or wet these valves will shut down or will act slow in recovery. Problem solved is drier change {a wax or acid removal ,if central system with two cartridge drier suggest one water control and one acid control drier}. The best bet is to pull valves out and install sporlan which has a bigger orifice to allow for leeser chance of plugging up. P.S. if these valves are cleaned as far as constant cleaning of driers I see no problem in these valves.