An ice maker control circuit for use with an ice maker of the type including an inclined refrigerated plate associated with means energized during an ice making cycle of operation to cause water to be continually circulated across the inclined plate as refrigerant is directed with respect thereto and wherein ice slabs built up on the plate are periodically released therefrom and directed to a cutting grid for separation into a plurality of cubes of ice; the control circuit including a bin ice accumulation switch responsive to a maximum build up of ice therein to terminate machine operation and an ice slab thickness control switch to selectively control circuit means for terminating the circulation of water over the plate and for initiating a hot gas defrost cycle of operation; the circuit further including a time delay thermal relay responsive to the bin ice accumulation switch sensing a maximum level of bin ice and operative to maintain an ice making cycle of operation until the ice slab reaches a desired thickness and thereafter conditioning a hot gas defrost solenoid to dislodge the slab from the refrigerated plate onto the grid so as to maintain the clarity of the ice slab; the thermal relay including means to maintain the hot gas defrost cycle for a time delay period followed by machine shut off.

A slab type ice maker including an inclined refrigerated plate assembly is associated with a mechanically driven refrigerant compressor to cool the plate below freezing during an ice making cycle of operation whereby water circulated thereover by means of a motor driven pump will produce an ice slab thickness on the plate which is removed therefrom during a hot gas defrost harvest cycle of operation to be directed onto a heated grid for separation into individual cubes which are collected in a storage bin having a bin level thermostat therein that operates when the bin is filled to terminate machine operation. A control circuit associated with the bin level thermostat switch includes a bimetallic thermostat associated with the bin switch to maintain the machine operative after bin fill to assure completion of a desired ice slab thickness on the plate assembly and further includes means to establish a hot gas defrost operation which is terminated by the bimetallic thermostat sensing flow of hot defrost gas to produce a time delay control of hot gas harvest of the slab with subsequent complete termination of machine operation when the bin is filled with ice.

A slab-type ice maker apparatus wherein a slab of ice is formed on an inclined evaporator plate by the flowing of water over the upper surface of the refrigerated plate. A control is provided for sensing the temperature of the evaporator plate so as to determine when the thickness of the ice slab reaches a minimal preliminary thickness and continuing the ice slab formation for a preselected period of time subsequent to that determination to provide the completed final thickness slab. The thermally responsive sensing structure is mounted to the underside of the evaporator plate for improved sensing operation. The rate of flow of the water is reduced subsequent to the determination of the formation of the minimal thickness slab for improved efficiency in completing the formation of the final slab. Sensing structure is provided for determining the transfer of the ice slab to a slab dividing grid from the refrigerated plate. A subsequent ice making cycle is initiated a preselected period of time after termination of a previous ice making cycle notwithstanding a failure of the ice slab to move fully onto the dividing grid. The control requires a signal indicating the end of the ice forming cycle as well as a signal from the level sensing elements to effect a termination of the ice maker operation.