Abstract: A heat pump is provided with a reversible fan motor in its outdoor coil and, after a delay period following initiation of the defrost cycle, the fan is caused to operate in a reverse direction to thereby cause the surrounding air to flow through the outdoor coil in a direction opposite to that in which it flows during the heating mode operation. During this time, the fan is operated at a relative slow speed to thereby prevent the convective flow of heat upwardly, while at the same time causing little, if any, flow of ambient air downwardly into the coil.

Abstract: A method and apparatus to refrigerate air in a compartment wherein liquid CO2 is delivered through a first primary heat exchanger such that sufficient heat is absorbed to evaporate the liquid carbon dioxide to form pressurized vapor. The pressurized vapor is heated in a gas fired heater to prevent solidification of the pressurized carbon dioxide when it is depressurized to provide isentropic expansion of the vapor through pneumatically driven fan motors into a secondary heat exchanger. Orifices in inlets to the fan motors and solenoid valves in flow lines to the fan motors keep the vapor pressurized while the heater supplies sufficient heat to prevent solidification when the CO2 vapor expands through the motors. CO2 vapor is routed from the second heat exchanger to chill surface in a dehumidifer to condense moisture from a stream of air before it flows to the heat exchangers.

Abstract: An outdoor unit includes at least a variable-capacity compressor and an outdoor heat exchanger coupled thereto. Each of a plurality of indoor units includes at least an indoor heat exchanger and a section for outputting required capacity data. A distribution unit parallel-couples the plurality of indoor units to the outdoor unit so as to constitute a plurality of refrigeration cycles for at least heating operations. The distribution unit includes a plurality of refrigerant flow control valves for the respective refrigeration cycles. A first control section provides flow rate control commands to the refrigerant flow rate control valves, in accordance with the required capacity data, and controls an operating frequency to change a capacity of the variable-capacity compressor in accordance with sum data of the required capacity data.

Abstract: A method and apparatus to refrigerate air in a compartment wherein liquid dioxide is delivered through a first primary heat exchanger such that sufficient heat is absorbed to evaporate the liquid carbon dioxide to form pressurized vapor. The pressurized vapor is heated in an external heat exchanger to prevent solidification of the pressurized carbon dioxide when it is depressurized to provide isentropic expansion of the vapor into a secondary heat exchanger. Pneumatically driven motors are driven by the pressurized carbon dioxide vapor to move air across the heat exchangers. Orifices in inlets to the motors and solenoid valves in flow lines to the motors keep the vapor pressurized while the external heat exchanger supplies sufficient heat to prevent solidification when it expands through the motors.

Abstract: A heat pump diagnostic and control system for controlling indoor coil freeze-up when in the cooling mode is provided. A low indoor coil temperature is sensed, the indoor fan speed is increased in steps up to a maximum to thaw the frost on the indoor coil. If this is not sufficient, the compressor speed is then reduced in steps until it is turned off and if necessary, it is held off until such time as the temperature sensor indicates thawing of the indoor coil of the heat exchanger. Diagnostic flow chart and control circuitry for accomplishing this control are disclosed.

Abstract: A refrigerating circuit apparatus includes a two stage compressor having an upper stage compressing cylinder and a lower stage compressing cylinder, a heat stage tank, an upper stage side variable opening expansion valve and a lower stage side variable opening expansion valve. The upper stage side variable opening expansion valve is controlled toward its closed position for executing a heat storing operation wherein heat is discharged from refrigerant to the heat storage tank. The upper stage side variable opening expansion valve is opened and the lower stage side variable opening expansion valve is closed for carrying out a defrosting operation. Heat stored in the heat storage tank is used in the defrosting operation for removing frost accumulated on an external heat-exchanger during the heating operation.

Abstract: A defrosting controller for use with a refrigeration system determines calculating a frost melting period from the measurements of the evaporator temperature during defrosting by means of an evaporator temperature sensor, establishes a refrigerating operation rate which is the ratio of the period of the frost melting process to the (total) open period of an electronic motor-driven valve during the refrigeration, and then decides whether the next defrosting operation is to be skipped or not.

Abstract: An air conditioner is disclosed which includes a unit for setting a defrost mode, as required, when the heating operation mode is determined, a unit for enabling the refrigerant which is delivered from the compressor to flow through one or more indoor units calling for the heating operation mode, when the defrost mode is set, and to be returned back to the compressor through one or more indoor units calling for the cooling operation mode, and a unit for enabling a stream of the refrigerant which is delivered from the compressor to pass through the outdoor heat exchanger, when the defrost mode is set, and to enter the stream of the refrigerant flowing into one or more indoor units calling for the cooling operation mode.

Abstract: A refrigerator having an enclosed compartment for storing food to be cooled, an evaporator including a refrigerant flowing therethrough for cooling the food in the compartment, a defrosting device, and a defrost override device. The defrosting device periodically heats the evaporator for removing the accumulated frost for controlled periods. The defrost override device automatically deactivates the defrosting device when the heating of the evaporator continues for longer than a preset time. The defrost override device may also automatically activate the refrigerant flowing through the evaporator. In this manner the refrigerator of this invention can store food without overheating during the defrosting operation.

Abstract: A low-temperature foods preserving case and a temperature control method therefor, in which a plurality of evaporators, each partitioned by partitioning panels, are arranged correctively in a cooling chamber, for which sequential cooling and defrosting operations are instructed by a timer, so that circulatory passage of the cooling air is formed through said cooling chamber, the foods preserving chamber, and the cooling chamber by means of fans installed in each of partitioned air passages separated by said partitioning panels.

Abstract: A refrigerating apparatus is conventionally provided with an electric which is fed with an electric current to effect heating and defrosting operations, a defrosting control device including a defrosting timer and an evaporator outlet refrigerant temperature detector for controlling the electric current fed to the electric heater, and an overheating preventing temperature detector for preventing the occurrence of abnormal overheating by the electric heater. The refrigerating apparatus of the present invention can regularly effect defrosting even if any anomaly should arise in the evaporator outlet refrigerant temperature detector. Specifically, the overheating preventing temperature detector is connected to the defrosting control device, and a detection temperature signal from either the evaporator outlet refrigerant temperature detector of the overheating preventing temperature detector is used to commence and terminate defrosting.

Abstract: A demand defrost controller employs temperature measurements taken at the outlet of the discharge air curtain and the inlet of the air return to determine the need for defrost. If the difference between these temperature measurements exceeds a set point for a predetermined sustained period of time and a minimum amount of time has elapsed since the last defrost of the case, defrost is initiated. Regardless of the value of the temperature difference, defrost is initiated if elapsed time since the last defrost exceeds a specified maximum time between defrosts for the case. Defrost can be terminated on the basis of time and/or temperature. The demand defrost controller can also control display case temperature and can be applied to independently control multiple display case circuits.

Abstract: A method for controlling the defrosting of evaporators provided for refrigerator-freezer units which are cooled by a single compressor. The method includes the steps of forcedly resetting the defrosting timer to its cooling mode after entering defrosting mode after the defrosting of a preset number of evaporators. The remaining undefrosted evaporators are warmed by their remaining heat after the forced resetting, by supplying electric current to their defrosting heaters sooner than the already defrosted evaporators in the next defrosting, by supplying additional electric current to their defrosting heaters after the forced resetting, by accomplishing a complete defrosting in an unsalable mode, by using outside air for defrosting by stopping their outer fans or by additional heating via auxiliary defrosting heaters.

Abstract: The present invention is a technique for a defrosting operation of a heat pump. External air provides the heat for defrosting the exterior heat exchanger by operating the exterior fan during times when the compressor is not operating, the temperature of the exterior heat exchanger is below freezing and the exterior air temperature is above freezing. In accordance with one embodiment of the present invention the temperature of the exterior heat exchanger and the exterior are measured via separate temperature sensors. In accordance with an alternative embodiment, the exterior heat exchanger temperature is measured via a single temperature sensor and the exterior fan is operated for a predetermined interval of time after the compressor is stopped. Thereafter the exterior fan is operated only so long as the temperature remains at freezing. In a still further embodiment, the exterior fan is operated only so long as it remains less than or equal to freezing and does not reach a plateau at less than freezing.

Abstract: The present invention is a technique for a defrosting operation of a heat pump. External air provides the heat for defrosting the exterior heat exchanger by operating the exterior fan during times when the compressor is not operating, the temperature of the exterior heat exchanger is below freezing and the exterior air temperature is above freezing. In accordance with one embodiment of the present invention the temperature of the exterior heat exchanger and the exterior are measured via separate temperature sensors. In accordance with an alternative embodiment, the exterior heat exchanger temperature is measured via a single temperature sensor and the exterior fan is operated for a predetermined interval of time after the compressor is stopped. Thereafter the exterior fan is operated only so long as the temperature remains at freezing. In a still further embodiment, the exterior fan is operated only so long as it remains less than or equal to freezing and does not reach a plateau at less than freezing.

Abstract: A refrigerating circuit apparatus includes a two stage compressor having an upper stage compressing cylinder and a lower stage compressing cylinder, a heat storage tank, an upper stage side variable opening expansion valve and a lower stage side variable opening expansion valve. The upper stage side variable opening expansion valve is controlled toward its closed position for executing a heat storing operation wherein heat is discharged from refrigerant to the heat storage tank. The upper stage side variable opening expansion valve is opened and the lower stage side variable opening expansion valve is closed for carrying out a defrosting operation. Heat stored in the heat storage tank is used in the defrosting operation for removing frost accumulated on an external heat-exchanger during the heating operation.

Abstract: A method for controlling the defrosting of evaporators provided for refrigerator-freezer units which are cooled by a single compressor. The method includes the steps of forcedly resetting the defrosting timer to its cooling mode after entering defrosting mode after the defrosting of a preset number of evaporators. The remaining undefrosted evaporators are warmed by their remaining heat after the forced resetting, by supplying electric current to their defrosting heaters sooner than the already defrosted evaporators in the next defrosting, by supplying additional electric current to their defrosting heaters after the forced resetting, by accomplishing a complete defrosting in an unsalable mode, by using outside air for defrosting by stopping their outer fans or by additional heating via auxiliary defrosting heaters.

Abstract: The present invention is a technique for a defrosting opereation of a heat pump. External air provides the heat for defrosting the exterior heat exchanger by operating the exterior fan during times when the compressor is not operating, the temperature of the exterior heat exchanger is below freezing and the exterior air temperature is above freezing. In accordance with one embodiment of the present invention the temperature of the exterior heat exchanger and the exterior are measured via separate temperature sensors. In accordance with an alternative embodiment, the exterior heat exchanger temperature is measured via a single temperature sensor and the exterior fan is operated for a predetermined interval of time after the compressor is stopped. Thereafter the exterior fan is operated only so long as the temperature remains at freezing. In a still further embodiment, the exterior fan is operated only so long as it remains less than or equal to freezing and does not reach a plateau at less than freezing.

Abstract: An ice maker including freeze and harvest controls is disclosed. The evaporator includes a unitary evaporator and ice mold. A compressor and condenser cool the evaporator to freeze ice on the mold in a normal refrigeration cycle and the mold is defrosted by hot gas to harvest ice from the ice mold. The temperature of the ice mold and the liquid line temperature of the condenser are sensed to control the length of time of the ice forming cycle.

Abstract: A method of defrosting a refrigerating circuit for use in cooling a vehicular chamber comprises two steps. In a first step a frost formed at an outer surface of an evaporator of a cooling unit is defrosted by directly leading discharged gas to the evaporator. In a second step a frost formed at elements of the cooling unit except the evaporator is defrosted by making air in the vehicular chamber pass through the heated evaporator. In this manner, the cooling down characteristic in the vehicular chamber is improved and compressor durability is preserved.

Abstract: Apparatus and method for defrosting a refrigerator in an operator actuated vacation mode wherein, after the operator actuation, the next defrost cycle is executed in accordance with the previously existing schedule in the normal defrost mode. If the time duration to execute the next defrost cycle is greater than a predetermined time period, the controller continues to defrost in the normal mode. However, if the next of a subsequent defrost cycle is executed in a relatively short time duration, the interval between defrost is significantly increased to a fixed interval of compressor run time hours.

Abstract: In the case of a process for controlling a heater, in particular a defrost heater for a refrigerating plant which has a temperature sensor, which is connected to a system for cutting in and cutting out the heater, during the operation of the heater, the temperature of the room to be heated is measured at certain intervals of time, a measured temperature value being stored in each case and compared with the following measured value, whereupon the heater is cut out whenever the following measured value indicates a temperature which is higher by a certain amount than the preceding stored measured value, and the heater is cut in or remains cut in whenever the following measured value indicates a temperature which is lower by a certain amount than the preceding stored measured value.

Abstract: The invention relates to a method and a device for compression of gases, in particular of air, within a compressed air piping system. The air drawn in for the compressor is cooled below 0.degree. C. within a freeze-dehumidifer in a cooling channel. The supply of undercooled refrigerant into the freeze-dehumidifier is interrupted during the defrosting of the freeze-dehumidifier situated within the cooling channel for the air drawn in towards the compressor. The condensate appearing in the form of ice on the freeze-dehumidifer is separated thereby. The defrosting operation is terminated after a pressure of the refrigerant corresponding to a positive temperature of the freeze-dehumidifier is exceeded, or after a presettable period has elapsed. The pressure of the refrigerant is monitored in the suction pipe and if appropriate in the delivery or pressure pipe of the refrigerant compressor.

Abstract: The present invention is an adaptive method and apparatus for detecting the formation of frost in a heat pump. The compressor cycle is interrupted and a defrosting operation is begun if the difference between the exterior ambient temperature and exterior heat exchanger temperature exceeds a difference function of the exterior ambient temperature. The length this defrosting cycle is measured and the difference function is altered if the measured length deviates from a predetermined length of time. The frost formation difference function is initially set as a linear approximation. Thereafter the difference function value at the particular exterior ambient temperature is increased if the length the defrosting is greater than an upper limit value of six minutes and decreased if the length the defrosting is less than a lower limit value of four minutes.

Abstract: The present invention is a method and apparatus for determining the exterior ambient temperature in a heat pump. In accordance with the prior art the heat pump defrosts the exterior heat exchanger if the exterior heat exchanger temperature has a predetermined relationship to the exterior ambient temperature. The exterior heat exchanger temperature is measured directly via a temperature sensor. The improvement of the present invention includes operating the exterior fan after operation of the compressor, while repetitively measuring the temperature of the exterior heat exchanger until reaching a plateau temperature other than freezing. The exterior ambient temperature is set to the plateau temperature. In the event that the plateau temperature equals freezing, the exterior ambient temperature is set equal to a compromise temperature slightly above freezing, preferably 34 degrees Fahrenheit.

Abstract: Defrost control, and a method of determining the need for defrost, of a transport refrigeration system which includes an evaporator coil disposed in an air flow path which returns air from a served space and discharges conditioned air back into the served space. The temperature of the air in the served space is measured by a digital thermostat for comparison with a preselected set point temperature, and the refrigeration system is operated with heating and cooling cycles to cause the temperature of the air to track set point. The digital temperature signal is monitored by the defrost control during each cooling cycle, and defrost of the evaporator coil is initiated as a function of the direction and rate of change of the air temperature.

Abstract: A defrosting system for a heat exchanger includes a temperature detector arranged adjacent to the exchanger, a temperature memory for storing temperature data detected by the detector, and a central processing unit, wherein when a second temperature which is detected by the temperature detector after normal operation requested by a user has restarted and after a predetermined minimum defrosting prohibitive time has passed, drops by a predetermined difference in temperature from a first temperature which is detected by the temperature detector after the normal operation has restarted and after a predetermined defrosting prohibitive time has passed, and the second temperature is a predetermined temperature or below; the central processing unit carries out the defrosting operation.

Abstract: A defrost system adapted for use with refrigeration or heat pump systems wherein an evaporator coil defrost cycle is adaptively modified in response to changing environmental conditions. Under normal conditions, a defrost operation is effected at the end of a period of frost accumulation. The period of frost accumulation is adjusted in accordance with deviation from a desired defrost time of the time required to raise the temperature of the coil from a first predetermined temperature to a second predetermined temperature. If a predetermined maximum defrost period is exceeded, the frost accumulation period is set to a predetermined value. During the frost accumulation period, the differential between the temperature of the coil and ambient temperature is determined, and the frost accumulation period terminated and a defrost operation initiated if temperature differential exceeds a target differential.

Abstract: A demand defrost controller for a heat pump. The controller compares the temperature of an outdoor heat exchange coil with an enable temperature. A timer is activated when the coil temperature is less than the enable temperature. When the timer senses the compressor has run for a predetermined time the controller checks outdoor and coil temperatures to determine if a defrost cycle of the heat pump should be conducted. A defrost cycle is achieved by reversing refrigerant flow in the heat pump system for a predetermined period or until the outdoor heat exchange coil has been heated to a termination temperature.

Abstract: A control system for controlling a heating system having a heat pump and a source of supplemental heat. The indoor heat exchanger temperature is monitored, such as by a thermocouple or the like, and when the temperature falls below a given threshold level, defrost cycling of the heat pump is initiated. The control system monitors the defrost cycling of the heat pump, and when the heat pump is in its defrost cycle for more than a predetermined portion of a heating cycle, the heat pump will be shut down until the outdoor ambient temperature has risen by a predetermined amount or a given interval of time has elapsed.

Abstract: When the temperature of an internal heat-exchanger decreases below a first value in cooling mode, a normal operation, wherein a variable capacity compressor operates in response to the temperature in a space to be cooled, stops temporarily, and a defrost operation, in which the driving frequency of the compressor periodically decreases by a prescribed value until the temperature of the internal heat-exchanger increases above a second value greater than the first value, begins. When the temperature of the internal heat-exchanger increases above a second value greater than the first value, the compressor operates in response to the temperature in the space. When the compressor stops during the defrost operation, the temperature of the internal heat-exchanger is compared with a third value greater than the second value and the operation of the compressor responding to the temperature in the space is inhibited until the temperature of the internal heat-exchanger increases above the third value.

Abstract: A defrost system adapted for use with refrigeration or heat pump systems wherein an evaporator coil defrost cycle is adaptively modified in response to changing environmental conditions. Under normal conditions, a defrost operation is effected at the end of a period of frost accumulation. The period of frost accumulation is adjusted in accordance with deviation of the time required to defrost a coil from a desired defrost time. During the frost accumulation period, the differential between the temperature of the coil and ambient temperature is determined, and the frost accumulation period terminated and a defrost operation initiated if temperature differential exceeds a target differential.

Abstract: This invention relates to a system for the control of electrical apparatus with particular reference to control by electric sensors, and with special reference to a control system for domestic appliances, such as refrigerators. The system may be adapted to control of appliances such as dishwashers, dryers, washers, stoves, etc. The preferred embodiment is microcomputer based. Thus, the system enables lower energy consumption, more accurate temperature maintenance and more effective servicing and monitoring of the mechanical condition of the apparatus to which it is applied.

Abstract: A cold accumulation type refrigerator having an improved control system for controlling its defrost cycle. The refrigerator includes a main evaporator for producing cold air, a cooling command signal generating device for generating a cooling command signal when a refrigerator compartment is required to be cooled, a clock device for generating a time data, a refrigerating cycle for cooling the main evaporator in accordance with the cooling command signal and the cold-accumulation material in accordance with the time data from the clock device, and a defrost control device for removing frost deposited on the main evaporator. The defrost control device counts cooling operation time of the evaporator in response to the cooling command signal.

Abstract: An outdoor coil temperature detection scheme in a heat pump system effective for developing outdoor ambient temperature indications from outdoor coil temperature data, for use in heat pump control.

Abstract: A refrigerating apparatus includes a compressor, a condenser, an expansion valve and an evaporator interconnected in that order. A hot gas bypass pipeline with a solenoid valve is connected at one end between the compressor and the condenser and at the other end between the expansion valve and the compressor. A temperature detecting switch detects a temperature of the piping between the discharge side of the evaporator and the intake side of the compressor. The temperature at which the detection switch can respond is set at a predetermined value at which no influence is exerted on components of the apparatus formed of thermoplastic resin. When the temperature at the intake side of the compressor rises to the predetermined value, the detecting switch detects this predetermined value to cause the compressor to stop operating.

Abstract: In a temperature control system when can be operated as a heat pump, frost deposited onto an outdoor heat exchanger (evaporator) is detected by a change in temperature of the refrigerant which flows into an indoor heat exchanger (condenser), so that a sensor to detect the deposition of the frost need not be attached to the outdoor heat exchanger. The refrigerant temperature is measured at the inlet of the indoor heat exchanger, and the temperature control system is switched to defrosting operation on the basis of this temperature and various elapsed time periods if the actual heat capability of the incoming refrigerant is insufficient, detecting the temperature of the refrigerant on the inlet side of the indoor heat exchanger, namely, by detecting the temeprature at a single position.

Abstract: Frostless type refrigerator/freezers having a plastic liner utilize a metal heat shield disposed between an evaporator and the liner. A defrost heater located below the evaporator is controllably energized to melt frost away from the evaporator. A metal clip of spring steel removably mounts a thermostat to the heat shield above the evaporator to sense the temperature above the evaporator to de-energize the heater when the frost is melted from the evaporator.

Abstract: An air conditioner having a defrosting mode of operation is disclosed, in which an outdoor heat exchanger is divided into two heat exchanger units juxtaposed in tandem with each other along the direction of air passage. In defrosting mode, a part of the refrigerant from the compressor is supplied to the upstream outdoor heat exchanger unit deposited with frost, and the rest of the high-temperature high-pressure refrigerant is supplied to the indoor heat exchanger to maintain the room temperature.

Abstract: A self-contained ice making machine includes a programmable controller connected to control operation of the machine which includes monitoring the operation of the machine for producing diagnostic type error signals for display, and issuing operating instructions to the refrigeration unit. The refrigerator unit has a condenser with cooling fans, evaporator, a water supply means, and an ice harvest probe assembly. The evaporator includes a coil, and an array of ice cube molds. The water supply means includes a water tank for flowing water over the evaporator, a pump for pumping water to the evaporator and from the tank and a solenoid controlled valve for controlling the flow of water to and from the tank. The ice harvest probe assembly includes a probe driven by a slip clutch motor for pushing against an ice cube bearing slab formed on the evaporator during ice cube harvest.

Abstract: An air conditioner includes a compressor, a four-way valve, an indoor heat exchanger, an expansion valve, an outdoor heat exchanger which are connected via pipings to form a heat pump type refrigerant circuit, the four-way valve being switched over to select a heating or cooling mode of operation. This air conditioner is further provided with a first and second branch pipes which extend from an outlet conduit of the compressor, the first branch pipe forming a first bypass pipe connected to an inlet conduit of the compressor. The first and second branch pipes have first and second valves, respectively. The air conditioner is also provided with a microcomputer for selectively opening and closing the second valve in response to the degree of superheating of discharged gaseous refrigerant after the first valve has been opened so that the discharged gaseous refrigerant is supplied to the outdoor heat exchanger to effect a defrosting operation while a heating operation is continued.

Abstract: An adaptive defrost system for a heat pump wherein the time-between-defrosts is continuously updated by multiplying the last time-between-defrosts by a ratio of the desired and actual differences between the pre-defrost and after-defrost saturated coil temperatures. A single thermistor is used for both pre and after-defrost measurements such that no calibration is required.

Abstract: A dehumidifier includes a humidistat switch to provide power to the compressor and fan when the ambient humidity exceeds a given level. The power to the compressor is also controlled by a thermostat switch and a timer. When the dehumidifier is operating in an environment that is below a given temperature, the compressor is periodically turned off for a short interval to melt any ice that has formed on the compressor coils.

Abstract: An ice maker is provided with a safety control for preventing overheating of a mold. The mold is thermally coupled to a thermostat having a switch used for de-energizing a defrost heater which melts frost away from an evaporator. The ice maker is electrically connected with a switch of the defrost thermostat switch so that when the defrost thermostat senses the preselected high temperature of the mold, the ice maker is de-energized to prevent overheating of the mold.

Abstract: A low-temperature showcase comprises a heat insulated wall, on the top of which an opening for putting-into or taking-out commodities is formed. The inside of the heat insulated wall is divided into an air passage and a storage chamber thereover by a dividing plate which is installed inside this heat insulated wall in a nearly horizontal fashion. The air passage is formed in a manner that the cross-section thereof is of a U-shape, and the storage chamber is formed surrounded by this air passage. At both ends of the air passage, vent ports are formed at the positions facing each other through the opening of the heat insulated wall inbetween. The air passage is divided into two parts by a fan case corresponding to the respective vent ports and a blast fan which can rotate reversibly is supported by this fan case. In each halved air passage, an evaporator is installed in the vicinity of the vent port, and when one of the evaporators is put in cooling operation, the other evaporator is subjected to defrosting.

Abstract: An air conditioning apparatus comprises a refrigerant circuit in which a compressor, a four-way valve, a room side heat exchanger, a pressure-reducing device and an outdoor side heat exchanger are connected in this order, wherein there is provided with a refrigerant temperature detector provided at a pipe line near the outdoor side heat exchanger, a room temperature detector for detecting temperature of a room and a controlling device which is electrically connected to the refrigerant temperature detector and the room temperature detector, said controlling device controlling operations for room-warming and defrosting based on inputs from the detectors.

Abstract: An adaptive defrost control for a refrigeration device alternately operated in cooling and defrosting cycles includes means for detecting the rate of change of temperature of an evaporator of the refrigeration device during a defrosting cycle, means for determining the length of time the rate of change of evaporator temperature remains at substantially zero and means for establishing the duration of a subsequent cooling cycle in dependence upon the determined length of time. The determined length of time is indicative of the magnitude of the frost load that formed on the evaporator and the length of the next cooling cycle is adjusted in accordance therewith so that the magnitude of the frost load built up on the evaporator in subsequent cooling cycles is forced toward a value which increases the efficiency of the refrigeration device.

Abstract: Described herein is a refrigeration defrost cycle monitoring and bypass circuit which monitors the condition of the defrost terminator switch. More specifically, the circuit monitors whether the defrost terminator switch is stuck in either the open or the closed position. This is accomplished using timers to determine the period of time of the defrost cycle and the period of time the terminator switch is open. If either of these times exceed preset values, the defrost terminator switch function is eliminated from the circuit and the control it normally performs is substituted by predetermined times. This occurs by providing a resettable ground to the defrost relay so that it can sense the need to defrost and initiate a defrost cycle. After a defrost cycle is initiated, a user selectable timer ends the defrost cycle after the selected time.

Abstract: A refrigerator temperature and defrost control according to the present invention includes means for sensing the temperature of a portion of cooling means within the refrigerator, means for determining when a particular frost load has accumulated on the portion of the cooling means, means coupled to the determining means for energizing defrost means for de-icing the portion of the cooling means when the particular frost load has accumulated and means coupled to the sensing means for de-energizing the defrost means when at least a portion of the frost load has been removed and for energizing the cooling means when the temperature of the portion thereof reaches a predetermined temperature during the time the defrost means is de-energized. The temperature and defrost control of the present invention makes multiple use various components thereof to reduce the cost and complexity of the control and to increase the effectiveness thereof.

Abstract: Disclosed are apparatus and methods for controlling the defrosting of the outdoor heat exchange coil of a heat pump. In general, the disclosed apparatus and methods use the differencee between the outdoor heat exchanger and the outdoor ambient temperature to determine when to initiate a defrosting operation. Only a single sensor is employed, this single sensor being positioned at least proximate the outdoor heat exchanger such that the sensor responds to ambient temperature when the heat pump is first started and the heat exchanger is free of frost, and such that the sensnor becomes surrounded with frost as frost builds up on the heat exchanger during operation. At the beginning of a run the sensor is employed to read the ambient temperature, which is memorized. As frost builds, the sensor begins to reflect the temperature of the heat exchanger as the sensor becomes increasingly insulated by the frost from the surrounding air.