Abstract: A batch type automatic icemaker adapted for installation in the freezing compartment of a refrigerator is provided with a thermal member having first and second ends. The first end of the thermal member is in communication with at least one of the ice-forming cavities and positioned below the water level. The second end projects into the cold air within the freezer. The second end is of a substantially larger mass than the first end. Since the first end is of a small mass relative to the second end and is thermally isolated from the mold, the cold freezer air cools it at a much faster rate than the water in the mold or the mold itself. The cooler surface of the first end chills the water in contact with it with a minimum of supercooling.

Abstract: A demand defrost control system which bases the interval between future defrosting operations on the time (heater ON time) required for the defrost heater to raise the evaporator temperature to a predetermined temperature during a previous defrosting operation. There is an inverse relationship between heater ON time and defrost intervals. Additionally, an override is provided which measures the time the compressor and evaporator are energized during any single operation cycle. If this time exceeds a predetermined length of time, the interval before the next defrosting operation is shortened.

Abstract: A batch type automatic icemaker adapted for installation in the freezing compartment of a refrigerator is provided with a water-carrying member having first and second ends. The first end of the water-carrying member is in fluid communication with at least one of the ice-forming cavities and positioned to be wetted by water therein. The second end projects into cold air within the freezer. A small quantity of water is thereby carried out of the ice-forming cavity to the second end of the member and exposed to cold air within the freezing compartment. Because the small quantity of water is of small mass and is thermally isolated from the mold, it is rapidly lowered to a temperature sufficiently low to reliably form a seed ice crystal. The seed ice crystal initiates freezing of the bulk of the water in the ice-forming cavities with a minimum of supercooling.