Abstract: An ice thickness controller is used to monitor the ice thickness in a refrigeration system. The system has a compressor connected to evaporator tubes which are submerged in a container of water. A DC motor has a shaft extending below the water line in the container. The motor is periodically turned on and a sensing circuit monitors the motor current. If the ice bank in the container is at the correct thickness, the motor shaft will be frozen into the ice. The current draw of the stalled motor will be high with the result that the sensing circuit will turn the compressor off. If the ice bank thickness is low, the motor shaft is free to rotate, so the motor current will be low and the sensing circuit will turn the compressor on.