A refrigerator includes at least a first compartment cooled to a first temperature and a second compartment cooled to a second temperature, and a multiplex damper system disposed in a cooling-air passage so as to selectively direct the cooling-air flow from the refrigeration apparatus to the compartments. The multiplex damper system comprises a single movable control damper mounted in the cooling-air passage and a drive control system responsive to the cooling demands of the respective compartme...

An improved system and method for controlling the temperature of a resistance heater in a heating, ventilation and air-conditioning ("HVAC") system is disclosed. The control circuit and method includes three separate thermostats per heater leg and are designed to trip at three, sequential pre-selected temperatures to address certain issues associated with prior art designs for thermal overload protection. One of the thermostats is of an automatically resettable type wherein the remaining two are...

A detection apparatus for detecting refrigerator door openings is coupled to at least one switch configured to be activated by a door opening. When the door is opened, the switch is activated and inputs a signal to the detection apparatus. The detection apparatus rectifies the signal; and phase-shifts the rectified signal so that it leads or lags the line voltage. The shifted output signal is fed to a processor that detects the opening of the door based upon the shifted signal. Signals output by...

An air flow control arrangement for a side-by-side refrigerator which results in temperature variations, both spatial and temporal, of approximately about .+-.1.degree. F. in the fresh food compartment, is described. Such air flow control also is believed to even further reduce the internal "sweat" in the fresh food compartment. In one embodiment, and with respect to a side-by-side refrigerator, the middle duct in the center mullion wall is closed off, and a duct is added in the center mullion w...

An electronic controller for an automatic icemaker includes a thermistor coupled to an icemaker mold, a first transducer coupled to a rake, a second transducer coupled to a feeler arm, and a processor. Time and temperature dependent calculations are summed at successive time intervals and compared to a predetermined value to determine when ice is frozen and ready for harvesting. Harvesting is delayed a pre-selected time based upon the position of the feeler arm to avoid premature harvesting. A h...

An adaptive defrost control includes a microcomputer for controlling the initiation and termination of a defrost operation based, at least in part, on opening of the fresh food door and the freezer door. The control monitors the compressor run time and the fresh food and freezer door open times and adjusts the time until defrost accordingly. A pre-chill operation cools the freezer prior to defrosting the evaporator coils so that the defrost heat will have less of an affect on the maximum tempera...

A refrigeration system includes a first refrigeration chamber, a second refrigeration chamber in flow communication with said the first refrigeration chamber, a sealed system for producing desired temperature conditions in the first refrigeration chamber and the second refrigeration chamber, and a controller operatively coupled to the sealed system. The controller is configured to accept a plurality of user-selected inputs including at least a first refrigeration chamber temperature and a second...

A control system for an appliance utilizing a plurality of peripheral devices includes a controller and a communications bus coupled to the plurality of peripheral devices and to the controller. The controller is configured to receive data from the peripheral devices over the communications bus and transmit control operations to the peripheral devices based on the data received. The communications bus reduces overall wiring requirements due to elimination or reduction of power wiring of the peri...

A method for controlling speed in a pulse-width-modulation-controlled motor powered by a load voltage source is provided. The method includes the steps of measuring the motor load voltage, and setting a pulse-width-modulation duty cycle based on the measured voltage.