The coil Protection Lockout switch, model CPLS, is a temperature sensing control, used to act as a safety against Evaporator coil freeze up. It is designed to mount on the surface of a 3/4 in or 7/8 in suction line. Electrically, it is wired in series with the ''Y'' lead from the thermostat or zone control panel, to the compressor contactor coil or relay. The switch breaks (opens) shutting off-the compressor when the temperature of the pipe drops below 37 deg F. The switch will reset (close), restarting the compressor when the temperature of the pipe rises above 47 deg F. EWC strongly recommends installing a compressor time delay relay when a CPLS control is used.