Abstract: Refrigerant is circulated through a vapor compression system including a compressor, a gas cooler, an expansion device, and an evaporator. When a sensor detects that frozen water droplets form on the evaporator, a valve positioned between the discharge of the compression and inlet of expansion device is opened. Refrigerant from the discharge of the compressor bypasses the gas cooler and enters the inlet of the expansion device. The high temperature refrigerant melts the frost on the evaporator. As the frost melts, the passage of the evaporator is opened to allow air to flow through the evaporator.

Abstract: In a vehicle air conditioner, a controller calculates a first target post-evaporator temperature for defogging a windshield based on a detection humidity of a humidity sensor, and calculates a second target post-evaporator temperature for defogging the windshield regardless of the detection humidity of the humidity sensor. Then, the controller determines a smaller one between the first and second target post-evaporator temperatures, as a target post-evaporator temperature. Accordingly, even when the humidity sensor detects a humidity lower than an actual humidity of a passenger compartment when a blower operates by a low air-blowing amount, a windshield is prevented from fogging.

Abstract: A sound collecting device is provided which is designed to minimize adverse effects on an output caused by exposure of an electroacoustic transducer to the air. The device includes an electroacoustic transducer and a vibrating circuit. The transducer is exposed to the air and responsive to input of a sound wave to produce a corresponding acoustic signal. The vibrating circuit vibrates the transducer to shake foreign substances such as dust or drops of water from the transducer. In a modified form, an electromagnetic sensor is provided which measures an electromagnetic noise transmitted to the transducer and which removes the electromagnetic noise from an output of the transducer to produce a noiseless acoustic signal.

Abstract: In an apparatus and a method for controlling operation of a compressor, by removing deviation generated by resistance and inductance and removing an error in a stroke estimation value of a compressor, operation of the compressor can be accurately controlled. The apparatus includes a counter electromotive force detector for detecting a counter electromotive force generated at a motor of a compressor. A stroke calculator calculates a stroke estimation value of the compressor on the basis of the counter electromotive force, and a stroke controller controls a stroke of the compressor by varying a voltage applied to the motor on the basis of the calculated stroke estimation value and a stroke reference value.

Abstract: An external display device of a refrigerator which includes a microprocessor enabling a serial data transmission/reception between the external display device and a control unit included in the refrigerator. The microprocessor is coupled with a second microprocessor included in the control unit by two voltage supply lines and a minimum number of data transmission lines. Data transmission/reception between the two microprocessor is carried out in an asynchronous serial manner while using an appropriate data format so that each microprocessor recognizes the operation condition of the counter microprocessor. Accordingly, it is possible to simplify the configuration of signal lines required between the external display device and control unit, irrespective of the complexity of functions required.

Abstract: A method and apparatus for controlling the temperature of a cold plate is disclosed. The temperature of the cold plate is controlled by directing compressed refrigerant along a first path configured to supply cooled refrigerant to the evaporator of the cold plate, redirecting at least a portion of the compressed refrigerant along a second path configured to supply non-cooled refrigerant to the evaporator of the cold plate, comparing a temperature reading associated with the cold plate to a predefined temperature range, and incrementally controlling the portion of the compressed refrigerant redirected along the second path responsive to the compared temperature reading. The temperature of the cold plate may be controlled to defrost the cold plate by redirecting substantially all of the compressed refrigerant along the second path for a predefined period of time responsive to a shutdown indicator.

Abstract: Heating/defrost constructions of a very low temperature refrigeration system having a defrost supply circuit and a defrost return bypass circuit optimizing the heating/defrost cycle, preventing overload (excessive pressure) of its refrigeration process and protecting components from damaging temperatures. The defrost cycle operates continuously, when required, and provides a shorter recovery period between heating/defrost and cooling operating modes. The rate of the temperature change during cool down or warm up is controlled in an open loop fashion by controlled refrigerant flow in bypass circuits.

Abstract: A system and method for sensing and controlling the temperature of a heating, ventilation and air conditioning (HVAC) system utilizes an infrared sensor. The infrared sensor is used to detect temperature over several different areas on an evaporator surface on which a cold spot may occur. More preferably, the infrared sensor continuously scans the whole surface on the air outlet side of the evaporator. The sensed temperature is used to detect any cold spots that may dynamically form on the evaporator surface. The system is controlled in response to the detected temperature.

Abstract: A method for defrosting a household refrigeration appliance including a compressor and a defrost heater. After a controller indicates that it is time for a defrost cycle, the compressor is operated if the temperature of the appliance is greater than a set temperature. The compressor is stopped when a temperature of the appliance is equal to or less than the set temperature. After the step of stopping, the temperature of the appliance is raised while the defrost heater is inactivated. After the temperature is raised, the defrost heater is energized. The controller pauses for a drip time after deenergizing the defrost heater before allowing the compressor to run.

Abstract: An integrated refrigeration control (IRC) module is disclosed which combines both thermal and electrical protection to the main components of a refrigerator and uses sensor inputs to control the compressor. The IRC module employs triacs (Q2, Q4, Q6, Q8, Q10) to control power to the start and run windings of the compressor motor, evaporator and compressor fans and the defrost heater. The module adaptively controls the refrigerator defrost cycle using previous defrost cycle run times to determine new cumulative compressor run times. Also disclosed is the use of preventive defrost periods performed for brief periods at intervals between portions of the cumulative compressor run time.

Abstract: An apparatus and a method are disclosed for controlling operation of a compressor capable of greatly decreasing a stroke estimation error of a compressor and controlling operation of the compressor accurately and precisely. The method includes calculating a first stroke estimation value of a compressor on the basis of current, a voltage applied to a motor of a compressor and preset parameters of the motor. Detecting a counter electromotive force of the motor and calculating a second stroke estimation value of the compressor on the basis of the detected counter electromotive force value.

Abstract: A control system for a refrigerator quick chill and thaw system comprises an electronic controller coupled to the operable components of a modular air handler for producing a convective airstream in a sealed pan for rapid chilling and safe thawing. The controller is configured to operate the air handler to execute a chill mode when selected by a user, operate the air handler to execute a thaw mode when selected by a user, adjust the air handler components for the selected chill mode or thaw mode, and maintain a constant temperature airstream in the pan to execute the selected chill mode or the thaw mode. Adaptive chill and thaw algorithms are executable by the controller in response to user input and temperature conditions inside the sealed pan.

Abstract: A refrigerator which uses a microcomputer having a common input port for a plurality of temperature sensing devices, and a method of controlling the same. In the refrigerator, inexpensive bimetals are used as one or more of the temperature sensing devices to sense a defrost temperature of the refrigerator. Accordingly, the manufacturing cost of the refrigerator is reduced. Furthermore, because the refrigerator is provided with the common input port for the temperature sensing devices, a circuit construction thereof is simplified.

Abstract: A method for defrosting a household refrigeration appliance including a compressor and a defrost heater. After a controller indicates that it is time for a defrost cycle, the compressor is operated if the temperature of the appliance is greater than a set temperature. The compressor is stopped when a temperature of the appliance is equal to or less than the set temperature. After the step of stopping, the temperature of the appliance is raised while the defrost heater is inactivated. After the temperature is raised, the defrost heater is energized. The controller pauses for a drip time after deenergizing the defrost heater before allowing the compressor to run.

Abstract: Disclosed are a defrosting apparatus of an air conditioner and a method thereof. The defrosting apparatus includes a temperature sensor for sensing a pipe temperature of an outdoor heat exchanger and an outdoor temperature; a comparator for comparing the sensed pipe temperature of the outdoor heat exchanger and the sensed outdoor temperature, and generating and outputting a comparison signal; and a valve controller for increasing an opening value of an LEV (Linear Expansion Valve) at a defrosting operation and decreasing the opening value of the LEV at a defrosting operation termination. The apparatus and the method can increase efficiency of the defrosting operation and reduce a period of time required for performing the defrosting operation by determining the defrosting operation based on a difference between a pipe temperature of an outdoor heat exchanger and an outdoor temperature and increasing an opening value of an LEV at the defrosting operation.

Abstract: A refrigerator with a multipurpose storage chamber and a control method. In the refrigerator, the flow of cool air to the multipurpose storage chamber is selectively controlled in accordance with a variety of operational modes. In order to accomplish such a cool air flow control, a refrigerating compartment fan and a damper are provided at positions above a refrigerating compartment evaporator. In addition, a flap, controlled at an open angle thereof, is provided at the inlet of an air guide path guiding the cool air to the multipurpose storage chamber. The multipurpose storage chamber of this refrigerator can thus effectively be used to store a variety of foods in accordance with storage characteristics of the foods. In addition, a thawing mode operation of the refrigerator is performed under the condition that it is not necessary to perform a refrigerating compartment cooling operation.

Abstract: In a vehicle air conditioner with a heat pump cycle having an interior heat exchanger and an exterior heat exchanger, when a frosting on a surface of the exterior heat exchanger is determined and when a temperature of hot water supplied to a heater core is equal to or higher than a predetermined temperature, the exterior heat exchanger is defrosted in a defrosting operation. Accordingly, the defrosting operation can be performed while a sufficient heating can be obtained.

Abstract: A defrost control system detects the variation in flow rate of refrigerant through an evaporator 8 while the flow is regulated to achieve a desired level of superheat at the outlet of the evaporator 8. When the flow rate becomes unstable, defrosting of the evaporator 8 is triggered.

Abstract: The present invention relates to a device and method for operating a refrigeration cycle without icing of the evaporative surface of the device.

Abstract: There is described a device for automatically preventing misting of the windscreen of a vehicle, wherein a number of sensors determine ambient conditions capable of misting the windscreen, and, upon such ambient conditions occurring, an electronic central control unit automatically activates the air-conditioning system of the vehicle to direct a stream of hot air onto the windscreen to raise its temperature and so prevent it from misting.

Abstract: Adaptive defrost control and method for a household refrigerator wherein a defrost heater is prevented from being powered as long as a compressor is running. The adaptive defrost control also provides a vacation mode in which the defrost interval is set to an artificially long interval if a door of refrigerator has not been opened for some predetermined period of time.

Abstract: A device and method for automatically defrosting a refrigeration system only during times of non-peak energy demand. The device is a defrost delay module that plugs into the current defrost timer supplied with frost-free refrigerators. The defrost delay module includes a microprocessor that utilizes a clock to define peak power consumption periods. If the defrost cycle will occur during a peak power period, the delay module interrupts the normal operation and prevents defrosting of a refrigerator or freezer until the peak power periods has passed. The delay module is able to learn the operating characteristics of the defrost timer such that the delay module can be retrofit to existing appliances.

Abstract: A refrigeration appliance is provided having a first compartment to be cooled, at least one evaporator in heat transfer association with the first compartment, a defrost heater associated with the evaporator, a temperature sensor associated with the evaporator, and a control circuit. The control circuit is arranged to selectively energize the defrost heater during a defrost cycle, selectively deenergize the defrost heater during the defrost cycle, generate a timing signal while the defrost heater is deenergized during the defrost cycle, and the control circuit is arranged to receive an input from the temperature sensor, and an accumulation of time from the timing signal.

Abstract: Heating/defrost constructions of a very low temperature refrigeration system having a defrost supply circuit and a defrost return bypass circuit optimizing the heating/defrost cycle, preventing overload (excessive pressure) of its refrigeration process and protecting components from damaging temperatures. The defrost cycle operates continuously, when required, and provides a shorter recovery period between heating/defrost and cooling operating modes. The rate of the temperature change during cool down or warm up is controlled in an open loop fashion by controlled refrigerant flow in bypass circuits.

Abstract: Disclosed are a defrosting apparatus of an air conditioner and a method thereof. The defrosting apparatus includes a temperature sensor for sensing a pipe temperature of an outdoor heat exchanger and an outdoor temperature; a comparator for comparing the sensed pipe temperature of the outdoor heat exchanger and the sensed outdoor temperature, and generating and outputting a comparison signal; and a valve controller for increasing an opening value of an LEV (Linear Expansion Valve) at a defrosting operation and decreasing the opening value of the LEV at a defrosting operation termination. The apparatus and the method can increase efficiency of the defrosting operation and reduce a period of time required for performing the defrosting operation by determining the defrosting operation based on a difference between a pipe temperature of an outdoor heat exchanger and an outdoor temperature and increasing an opening value of an LEV at the defrosting operation.

Abstract: A frosting cooler creates and maintains frost on cold products, such as bottles of a beverage stored in the cooler, thereby to provide a visual manifestation of the cold condition of the beverage. The cooler has the ability to deliver moisture to the products within the cooler so that frosting may be produced in environments where there is low humidity in the ambient air without freezing the liquid contained by the bottle. The cooler is operated to control to protect the frost on the products, once formed. In addition, the cooler is controlled to prevent frost build up on an evaporator and fan of the cooler in the presence of the additional moisture.

Abstract: An energy-saving method for operating a climate control system includes reporting an ambient outside temperature from a first temperature sensor to a controller unit and reporting a climate control air temperature from a second temperature sensor to the controller unit. The control unit performs an algorithm to define a control criterion value in response to the ambient outside temperature. A non-refrigeration cycle based heating element is activated to provide heated air to an interior surface of a windshield if the climate control air temperature is above the control criterion value. Moreover, a refrigeration cycle based cooling element and the non-refrigeration cycle based heating element are activated to provide the heated air to the interior surface of the windshield if the climate control air temperature is at or below the control criterion.

Abstract: A system and a method of automatic defrost for a refrigeration appliance, including a hermetic compressor driven by an electric motor (1); a control unit (2); a thermal switch means (10) having a first and a second turn on condition and a turn off condition and another turn off condition of the electric motor (1); a timer (20), which measures the periods of time in the turn on and turn off conditions of the electric motor (1); a switch means (40), which selectively interrupts the energization of the electric motor (1), by instruction of the control unit (2); and a cycle counting means (30), which counts each first and second turn on conditions of the electric motor (1), the control unit (2) selectively activating the thermal switch means (10) to operate in determined turn on and turn off conditions of the electric motor (1).

Abstract: Method and apparatus for providing an automatic defroster function for a surface in a vehicle including a sensor for detecting the presence of mist or ice on such a surface, means for generating control signals, on the basis of the sensor data, for a number of functions in the car for an optimum defroster function on said surface, means for receiving these control signals, and means for receiving control signals from a temperature regulator in the car for a number of functions in the car. A number of the control signals from the temperature regulator are intended to control the same functions as the control signals for the optimum defroster function, and the same means are used for receiving control signals for optimum defroster function and for receiving some of the control signals from the temperature regulator. The means for receiving control signals are intended, in the event of conflict, to select those control signals that are designed to give the best defroster function.

Abstract: A heat pump system includes an indoor unit and an outdoor unit, with a compressor, an outdoor fan, and a reversing valve all in the outdoor unit. A thermostat is added to the outdoor unit with one side of the thermostat connected to a high voltage line for either a compressor or a magnetic contactor and the other side connected to a high voltage line for either an outdoor fan or a reversing valve. A signal collection circuit in the indoor unit is connected to a high voltage line for the outdoor fan when the other side of the thermostat is connected to the outdoor fan and to a high voltage line for the reversing valve when the other side of the thermostat is connected to the reversing valve. The thermostat sends a signal to the electronic control board when the defrosting operation should be terminated.

Abstract: A method and apparatus for defrosting an evaporator of a refrigeration system including a defrost heater and a controller operatively connected to the evaporator and a defrost heater is provided. The method comprises initiating a defrost cycle to energize the defrost heater to defrost the evaporator, monitoring a temperature of the evaporator, terminating the defrost cycle by de-energizing the defrost heater when a low temperature termination point of the evaporator is reached when in a low temperature defrost cycle, and terminating the defrost cycle by de-energizing the defrost heater when a high temperature termination point of the evaporator is reached when in a high temperature defrost cycle.

Abstract: The invention is a method and a defroster control circuit to sequentially defrost a series of refrigerated display cases. The method begins by operating the series of refrigerated display cases during a normal refrigeration mode. At the beginning of the refrigeration mode, a refrigeration time is set to zero and an elapsed refrigeration time is subsequently monitored. When the refrigeration time equals an activation time, a defrost mode begins and a defrost cycle for the first case starts. The defrost mode for the first case terminates based either on a defrost time criterion or a defrost temperature criterion. After the first refrigerated display case is defrosted, a refrigeration mode is restarted for the first case. After the first refrigerated display case is defrosted, the other refrigerated display cases in the series of refrigerated display cases are then sequentially defrosted.

Abstract: An operation control apparatus and method of a linear compressor are disclosed. The operation control apparatus includes: an ambient temperature sensor unit for sensing a temperature around a refrigerator; a second microcomputer for outputting a control signal according to a temperature statue of a temperatures sensing unit for sensing an inner temperature of the refrigerator; a load driving unit for receiving an ON/OFF control signal for driving a linear compressor from the second microcomputer and outputting a drive signal to the linear compressor; a relay switched by the driving signal and supplying an AC power to a motor of the linear compressor; and a power supply unit for converting the AC power into a DC power and supplying power to each unit inside the linear compressor.

Abstract: Disclosed is a refrigerator for kimchi, including a main body having at least one cooling chamber, an evaporator for cooling the cooling chamber, a compressor for supplying a refrigerant to the evaporator, a refrigerant tube for supplying the refrigerant from the compressor to the evaporator, and a valve installed in the refrigerant tube for controlling the supply of the refrigerant. The kimchi refrigerator further comprises a temperature sensor for detecting the temperature of the cooling chamber; a heater installed in the main body, heating and defrosting the evaporator; and a controller for controlling the heater to perform the defrosting operation when the temperature of the cooling chamber detected by the temperature sensor is not more than a predetermined temperature. With this configuration, a layer of frost frozen in the evaporators can be removed effectively, to thereby further enhance a cooling efficiency and save a consumed power.

Abstract: A defrost control system for a self-defrosting refrigerator is configured to monitor a compressor load, determine whether at least a first defrost cycle is required based on the compressor load, execute at least one defrost cycle when required; and regulate the defrost cycle to conserve energy. A controller is operatively coupled to a compressor, a defrost heater, and a refrigeration compartment temperature sensor. The controller makes defrost decisions based on temperature conditions in the refrigeration compartment in light of other events, such as refrigerator door openings, completed defrost cycles, and power up events. Defrost cycles are automatically adjusted as operating conditions change, thereby avoiding unnecessary energy consumption that would otherwise occur in a fixed defrost cycle.

Abstract: An apparatus for removing deposits from a heat transfer wall of a heat exchanger. The apparatus includes a cleaning cycle control system that operates through the control system of the heat pump and eliminates the need for periodic acid cleaning of heat exchanger. The cleaning cycle control system engages a heating cycle of the heat pump to at least partially freeze the fluid adjacent to the heat transfer wall and then engages the cooling cycle of the heat pump to thaw the fluid adjacent to the heat transfer wall. The thermal expansion and contraction of the deposits on the heat transfer wall and the flow of fluids through the heat exchanger flush deposits from the heat transfer wall of the heat exchanger.

Abstract: Methods and apparatus for freezer defrost, which are particularly suited for an automated system, include the formulation of algorithms utilized for this purpose. The algorithms are included in the firmware of an embedded controller and operate the freezer defrost cycle at temperature lows for increased efficiency. An application of the freezer defrost method and apparatus is also disclosed.

Abstract: Adaptive defrost control and method for a household refrigerator wherein a defrost heater is prevented from being powered as long as a compressor is running. The adaptive defrost control also provides a vacation mode in which the defrost interval is set to an artificially long interval if a door of refrigerator has not been opened for some predetermined period of time.

Abstract: Method and apparatus for providing an automatic defroster function for a surface in a vehicle including a sensor for detecting the presence of mist or ice on such a surface, means for generating control signals, on the basis of the sensor data, for a number of functions in the car for an optimum defroster function on said surface, means for receiving these control signals, and means for receiving control signals from a temperature regulator in the car for a number of functions in the car. A number of the control signals from the temperature regulator are intended to control the same functions as the control signals for the optimum defroster function, and the same means are used for receiving control signals for optimum defroster function and for receiving some of the control signals from the temperature regulator. The means for receiving control signals are intended, in the event of conflict, to select those control signals that are designed to give the best defroster function.

Abstract: A refrigerator which uses a microcomputer having a common input port for a plurality of temperature sensing devices, and a method of controlling the same. In the refrigerator, inexpensive bimetals are used as one or more of the temperature sensing devices to sense a defrost temperature of the refrigerator. Accordingly, the manufacturing cost of the refrigerator is reduced. Furthermore, because the refrigerator is provided with the common input port for the temperature sensing devices, a circuit construction thereof is simplified.

Abstract: Heating/defrost constructions of a very low temperature refrigeration system having a defrost supply circuit and a defrost return bypass circuit optimizing the heating/defrost cycle, preventing overload (excessive pressure) of its refrigeration process and protecting components from damaging temperatures. The defrost cycle operates continuously, when required, and provides a shorter recovery period between heating/defrost and cooling operating modes. The rate of the temperature change during cool down or warm up is controlled in an open loop fashion by controlled refrigerant flow in bypass circuits.

Abstract: A heat pump system includes an indoor unit and an outdoor unit, with a compressor, an outdoor fan, and a reversing valve all in the outdoor unit. A thermostat is added to the outdoor unit with one side of the thermostat connected to a high voltage line for either a compressor or a magnetic contactor and the other side connected to a high voltage line for either an outdoor fan or a reversing valve. A signal collection circuit in the indoor unit is connected to a high voltage line for the outdoor fan when the other side of the thermostat is connected to the outdoor fan and to a high voltage line for the reversing valve when the other side of the thermostat is connected to the reversing valve. The thermostat sends a signal to the electronic control board when the defrosting operation should be terminated.

Abstract: A refrigerator with a multipurpose storage chamber and a control method. In the refrigerator, the flow of cool air to the multipurpose storage chamber is selectively controlled in accordance with a variety of operational modes. In order to accomplish such a cool air flow control, a refrigerating compartment fan and a damper are provided at positions above a refrigerating compartment evaporator. In addition, a flap, controlled at an open angle thereof, is provided at the inlet of an air guide path guiding the cool air to the multipurpose storage chamber. The multipurpose storage chamber of this refrigerator can thus effectively be used to store a variety of foods in accordance with storage characteristics of the foods. In addition, a thawing mode operation of the refrigerator is performed under the condition that it is not necessary to perform a refrigerating compartment cooling operation.

Abstract: A system and a method of automatic defrost for a refrigeration appliance, including a hermetic compressor driven by an electric motor (1); a control unit (2); a thermal switch means (10) having a first and a second turn on condition and a turn off condition and another turn off condition of the electric motor (1); a timer (20), which measures the periods of time in the turn on and turn off conditions of the electric motor (1); a switch means (40), which selectively interrupts the energization of the electric motor (1), by instruction of the control unit (2); and a cycle counting means (30), which counts each first and second turn on conditions of the electric motor (1), the control unit (2) selectively activating the thermal switch means (10) to operate in determined turn on and turn off conditions of the electric motor (1).

Abstract: A control system for a refrigeration system having a refrigeration compartment and a quick chill/thaw pan. A main controller board, electrically connected to a temperature adjustment board and a dispenser board through the serial communications bus, controls the temperature of the refrigeration compartment and the quick chill/thaw pan. The control system accepts a plurality of inputs to determine a refrigeration mode and to execute a plurality of software algorithms to control the refrigeration compartment as both a chill pan to rapidly chill food and beverage items without freezing and a thaw pan to timely thaw frozen items at controlled temperature levels.

Abstract: A method for controlling refrigeration including a simulated product temperature sensor operable to measure a simulated product temperature from a refrigeration case and a transceiver in communication with said simulated product temperature sensor and operable to wirelessly transmit data. A receiver receives the wirelessly transmitted data and a controller in communication with the receiver controls the refrigeration system based upon the wirelessly transmitted data from the refrigeration case.

Abstract: Adaptive defrost control and method for a household refrigerator wherein a defrost interval is adjusted based upon the time it takes for a previous defrost cycle to complete. The adaptive defrost control also provides a vacation mode in which the defrost interval is set to an artificially long interval if a door of refrigerator has not been opened for some predetermined period of time. Further a defrost termination thermostat is provided that is stable during power interruption. The termination thermostat is used as a memory device to determine whether a defrost cycle was in process when power was interrupted.

Abstract: A frosting cooler creates and maintains frost on cold products, such as bottles of a beverage stored in the cooler, thereby to provide a visual manifestation of the cold condition of the beverage. The cooler has the ability to deliver moisture to the products within the cooler so that frosting may be produced in environments where there is low humidity in the ambient air without freezing the liquid contained by the bottle. The cooler is operated to control to protect the frost on the products, once formed. In addition, the cooler is controlled to prevent frost build up on an evaporator and fan of the cooler in the presence of the additional moisture.

Abstract: The present invention relates to a device and method for operating a refrigeration cycle without icing of the evaporator of the device.

Abstract: A method and apparatus for operating a dehumidifier in a de-ice mode is provided wherein the dehumidifier has an evaporator coil, a fan operated by a fan motor to cause a flow of ambient air over the evaporator coil, and a compressor operated by a compressor motor to cause a flow of refrigerant to the evaporator coil. A control is provided for detecting a characteristic of the dehumidifier associated with the formation of frost on the evaporator coil. Such characteristic could be the temperature of the evaporator coil, the rate of change of the temperature of the coil, a drop in the amp draw of the compressor motor below a predetermined value or a predetermined rate of downward change in the amp draw of the compressor motor. The control terminates power to the compressor motor after detection of the characteristic, either immediately or after a predetermined time, while continuing operation of the fan to provide the melting.