Abstract: Heat pumps with improved defrost cycles and methods of defrosting heat exchangers, for example, having microchannel outdoor heat exchangers. A heat exchanger has three types of connection points that are used during a defrost cycle. Two connection points are used to deliver hot refrigerant gas to the heat exchanger and one connection point is where refrigerant exits the heat exchanger. Two of the connection points are at the same header and during at least part of the defrost cycle, at least part of the hot refrigerant gas is passed through that header without passing through any cross tubes of the heat exchanger. A defrost valve in a refrigerant conduit opens during the defrost cycle to deliver hot refrigerant gas to the connection point on the header. In a number of embodiments, the defrost valve is open only during a portion of the defrost cycle.

Abstract: An air conditioner is provided. The air conditioner includes a heat exchanger which exchanges heat with air by passing a coolant therethrough; and an anti-freeze apparatus which prevents the freeze of water on the surface of the heat exchanger by supplying energy to the heat exchanger. The air conditioner can prevent the freeze of water on the surface of the heat exchanger during its operation, and thus, there is no need to perform a defrost operation during the operation of the air conditioner. In addition, the air conditioner can continuously and efficiently perform an air conditioning function.

Abstract: Heat pumps with improved defrost cycles, methods of defrosting heat exchangers, and methods of improving the effectiveness of defrost cycles of heat pumps, for example, having a microchannel outdoor heat exchanger. A defrost valve in a refrigerant conduit opens during a defrost cycle to deliver hot refrigerant gas to a portion of the heat exchanger that otherwise defrosts more slowly or less completely than other portions of the heat exchanger. Particular embodiments pass hot refrigerant gas through a header of the heat exchanger, such as a bottom header. In a number of embodiments, the defrost valve is open only during a portion of the defrost cycle. Further, in some embodiments, the fan that is used to blow air through the heat exchanger is operated in a reversed direction during at least part of the defrost cycle to counteract natural convection through the heat exchanger.

Abstract: An energy saving defrost control system for reducing power consumption of an electromechanically controlled refrigerator is provided. The system includes a defrost timer configured to control a compressor according to an established run time, a defrost heater control operatively connected to the defrost timer and configured to activate a defrost heater in response to a timeout by the defrost timer, a DSM module responsive to demand state signals from an associated utility indicative of at least a peak demand and off peak demand state, and a time delay latching relay comprising a timer and configured to switch to one of a low position and a high position based on the demand state signal.

Abstract: An air conditioner is provided. The air conditioner includes a heat exchanger which exchanges heat with air by passing a coolant therethrough; an anti-freeze apparatus which prevents the freeze of water on the surface of the heat exchanger by supplying energy to the heat exchanger; and a control unit which controls the anti-freeze apparatus according to operating conditions of the air conditioner. Therefore, the air conditioner can effectively prevent the freeze of water, if any, on the surface of the heat exchanger.

Abstract: A refrigerator is provided that includes a chilled interior and a cooling circuit for a coolant, the cooling circuit being provided with an evaporator, a compressor, and a condenser. The refrigerator further includes a controller as well as a fan for cooling the condenser and the compressor. The controller controls the fan to operate during an idle phase of the compressor.

Abstract: A cooling tunnel includes an infeed port for feeding objects, a discharge port for discharging objects, successive treatment stations for treating the objects with a cooling medium, and a conveyor system for transporting the objects to be cooled from the infeed port to the discharge port, with the conveyor system travelling through the individual treatment stations. The conveyor system has a first section running through several treatment stations, the first section extending from the infeed port to a turnaround station, a second section running through several treatment stations, the second section extending from the turnaround station to the discharge port, as well as a return section, which is arranged before the discharge port and connects a discharge-side zone of the second section with an infeed-side zone of the first section, to selectively either discharge objects or to cool them further. A method for operating a cooling tunnel is also provided.

Abstract: A heat pump system includes a controller and a closed system that includes a condensing heat exchanger coil, an evaporating heat exchanger coil, a refrigerant and a compressor. The compressor is configured to compress the refrigerant, thereby causing the refrigerant to have a greater pressure in the condensing heat exchanger coil than in the evaporating heat exchanger coil. The controller is configured to perform a passive defrost of the evaporating heat exchanger coil. The passive defrost includes disabling the compressor and providing a bypass path between the condensing and evaporating heat exchanger coils that bypasses the compressor. The bypass path allows the refrigerant to flow from the condensing heat exchanger coil to the evaporating heat exchanger coil while the compressor is disabled.

Abstract: The defrost timer is typically provided to remove frost on an evaporator in a refrigerator. The defrost timer includes a circuit board, a first terminal, a second terminal, a third terminal, a fourth terminal, a switching unit, a first AC line, a second AC line, a third AC line and a fourth AC line. The first AC line is provided on the circuit board and connects the first terminal and the switching unit. The second AC line is provided on the circuit board and connects the second terminal and the switching unit. The third AC line is provided on the circuit board and connects the third terminal and the switching unit. The fourth AC line is provided on the circuit board and connects the fourth terminal and the switching unit. Distance between the third AC line and the fourth AC line is at least 5 mm.

Abstract: An air conditioner is provided. The air conditioner includes a heat exchanger which exchanges heat with air by passing a coolant therethrough; an anti-freeze apparatus which prevents the freeze of water on the surface of the heat exchanger by supplying energy to the heat exchanger; and a heat generation unit which heats the heat exchanger. The air conditioner can minimize the need for a defrost operation and can thus continuously and effectively perform an air conditioning function even when water on the surface of the heat exchanger is frozen.

Abstract: A method for defrost control of a refrigerator having a refrigeration and defrost system that includes a compressor, an evaporator, an evaporator fan and a heater. The refrigerator also has a control system to control the operation of the refrigerator. The method includes stopping the compressor operation; starting a defrost process; starting the heater; maintaining a start state over a preset period of time; closing off the heater; and starting the compressor. After starting the compressor and before the evaporator fan is started to perform the refrigeration operation, the evaporator fan is operated at least once briefly and intermittently.

Abstract: A refrigerator according to the present invention includes a compressor compressing a coolant, a condenser condensing the coolant compressed in the compressor, an expander through which the coolant condensed in the condenser passes, an evaporator evaporating the coolant expanded in the expander and cooling an inside of the refrigerator, a defroster defrosting the evaporator, a coolant adjusting valve adjusting the coolant flowing from the condenser to the evaporator, and a controller driving the compressor and turning on the defroster after closing the coolant adjusting valve. The refrigerator may minimize power consumed for defrosting and the defrosting time.

Abstract: Provided is a method and system for forming ice pieces with an ice maker that includes a mold defining a plurality of cavities for receiving water to be frozen into ice pieces. A processor controls delivery of a refrigerant to freeze water received in the plurality of cavities into ice pieces. A freeze signal transmitted by a temperature sensor embedded within the mold is received by the processor, the freeze signal indicating that a temperature of a portion of the mold adjacent to the temperature sensor has reached a freeze temperature where the water in at least one of the cavities has achieved a frozen state to initiate harvesting of the frozen ice pieces. Defrosting a system evaporator can also be coordinated with operation of the ice maker.

Abstract: A high performance refrigerator includes a cabinet with a unitary refrigerated interior and a refrigeration fluid circuit having first and second evaporators located within the cabinet and separated from the refrigerated interior by respective first and second evaporator covers. The refrigerator also includes a first damper controlling flow between the first evaporator and the refrigerated interior, and a second damper controlling flow between the second evaporator and the refrigerated interior. A controller directs the refrigerator to operate a three-way valve in the refrigeration fluid circuit so as to direct refrigerant to only one of the evaporators when the other requires defrosting. Both evaporators may be used to remove heat from the unitary refrigerated interior during an initial cooling or immediately after the cabinet is opened.

Abstract: A high performance refrigerator includes a cabinet with a refrigerated interior and a refrigeration fluid circuit having first and second evaporators located within the cabinet and separated from the refrigerated interior by an insulating cover. The refrigerator also includes a first damper controlling flow from the refrigerated interior into the first evaporator, a second damper controlling flow from the first evaporator to the second evaporator, and a third damper controlling flow from the second evaporator to the refrigerated interior. The first evaporator operates with refrigerant at a lower temperature than the second evaporator such that substantially all frost formed on the first and second evaporators is collected on a first evaporator coil in the first evaporator. Thus, the first evaporator acts as a sacrificial evaporator that undergoes defrost more frequently than the second evaporator.

Abstract: A refrigerator includes a low-temperature storage compartment damper to control supply of cool air to a low-temperature storage compartment, a high-temperature storage compartment damper to control supply of hot air to a high-temperature storage compartment, and a controller to control the low-temperature storage compartment damper to be opened and the high-temperature storage compartment damper to be closed while controlling a compressor and blowing fan to be driven so that the temperature of the low-temperature storage compartment reaches a low set temperature, to control the driving of the compressor and blowing fan to be stopped and the low-temperature storage compartment damper to be closed when the temperature of the low-temperature storage compartment reaches the low set temperature, and to control a defrosting heater and the blowing fan to be driven and the high-temperature storage compartment damper to be opened when the supply of cool air is stopped.

Abstract: In apparatus to convert cryogenic fluid to gas, a vaporizer having passages to pass the cool or cold cryogenic fluid in heat transfer relation with warming gas flowing downwardly through the vaporizer, the vaporizer having surfaces on which ice collects and from which ice falls to the base of the vaporizer and collects in a pile, and removing fluid flow control means operating to direct flow of removing fluid at the ice pile with sufficient force to cause removal of such ice in the pile relative to the vaporizer base.

Abstract: A system and a method are provided for returning oil in a heating, ventilation, and air conditioning (HVAC) system by determining when an ambient zone temperature is equal to or less than a temperature limit and reversing a direction of refrigerant flow of the HVAC system based on the length of time. Also, a system and a method are provided for monitoring the length of operation in a first and a second heating mode and for reversing a direction of refrigerant flow based on the length of time operation occurs in the first and second heating modes. A system and a method having a first compressor, a first heating mode, a second heating mode, a defrost mode, and a controller is disclosed. The controller selectively controls initiation of the defrost mode in response to an HVAC system operating in a heating mode of operation for a predetermined amount of time.

Abstract: In a controller for a refrigerating system including refrigerating machines and showcases, a showcase that is about to execute a defrost operation is detected on the basis of a defrost operation indicating information. When the controller receives a notification indicating start of the defrost operation from the showcase concerned or on the basis of a comparison result between a pre-stored defrost-operation start time and the present time, at least one of the refrigerating machines is instructed to reduce the output power thereof. When the showcase finishes the defrost operation, the at least one of the refrigerating machines is instructed to increase the output power thereof so that the output power of the refrigerating machine is set to stationary output power.

Abstract: An equipment control system for equipment such as a refrigeration device, its control device, and its control program are provided in which defrosting operation start time can be changed appropriately. The integrated controller controls a defrosting operation to remove frost adhered to the equipment, in which the defrosting operation is started at a fixed or varying time interval. The integrated controller stores past data based on required time for past defrosting operations for different environmental conditions. The integrated controller includes an environmental condition acquisition unit for obtaining environmental conditions; a database control unit for obtaining required time for a defrosting operation based on the past record data corresponding to the present environmental conditions from the stored past data; and a start time changing unit for changing start time of the present-round defrosting operation based on the obtained required time.

Abstract: A refrigeration cycle that is formed by connecting a compressor, a condenser, expansion means, and an evaporator and that performs cooling operation; an evaporator heating device that heats the evaporator; a drain pan that receives drain-water from the evaporator and drains the drain-water; a drain-pan heating device that heats the drain pan; frost detecting means including a light-emitting element that emits light to the evaporator and a light-receiving element that receives reflected light from the evaporator and outputs a voltage according to the reflected light; and a control device that controls on-off operation of the evaporator heating device and the drain-pan heating device. The control device determines a frosting condition on the evaporator from an output of the frost detecting means and individually controls the evaporator heating device and the drain-pan heating device in accordance with the determination result.

Abstract: An equipment control system includes a control device, and a control program in which present-round defrosting operation start time can be changed appropriately. An integrated controller controls a defrosting operation to remove frost adhered to showcases, in which the defrosting operation is started at a fixed or varying time interval. The integrated controller stores past record data based on required time for past defrosting operations for different environmental conditions. The integrated controller includes an environmental condition acquisition unit for obtaining present environmental conditions; a database control unit for obtaining required time for a present-round defrosting operation based on the past record data corresponding to the present environmental conditions from among the stored past record data; and a start time changing unit for changing start time of the present-round defrosting operation based on the obtained required time from the scheduled start time.

Abstract: A system and a method are provided for returning oil in a heating, ventilation, and air conditioning (HVAC) system by determining when an ambient zone temperature is equal to or less than a temperature limit and reversing a direction of refrigerant flow of the HVAC system based on the length of time. Also, a system and a method are provided for monitoring the length of operation in a first and a second heating mode and for reversing a direction of refrigerant flow based on the length of time operation occurs in the first and second heating modes. A system and a method having a first compressor, a first heating mode, a second heating mode, a defrost mode, and a controller is disclosed. The controller selectively controls initiation of the defrost mode in response to an HVAC system operating in a heating mode of operation for a predetermined amount of time.

Abstract: To achieve a reduction in power consumption by allowing a plurality of air conditioners to communicate with each other and thereby leveling their air-conditioning capacities with no load variations involved by temperature variations. An air-conditioning apparatus 100 may include a plurality of air conditioners and a computing section for control, where each air conditioner includes an indoor unit and an outdoor unit that form a closed refrigeration cycle. The indoor units of the plurality of air conditioners are installed in an area to be air-conditioned. The computing section for control may allow the plurality of air conditioners to communicate with each other, thereby leveling their air-conditioning capacities based on air-conditioning load detected by each air conditioner.

Abstract: A container refrigeration system includes a refrigerant circuit configured to perform a refrigeration cycle and including a main circuit in which a compressor, a condenser, an expansion valve, and an evaporator are connected together in this order, and a hot gas bypass circuit in which compressed refrigerant of the compressor is supplied to the evaporator by bypassing the condenser and the expansion valve; and a compressor control section configured to, in a defrosting operation in which the compressed refrigerant of the compressor returns to the compressor through the hot gas bypass circuit and the evaporator and the evaporator is defrosted, control an operating speed of the compressor such that a pressure of the compressed refrigerant of the compressor reaches a target value.

Abstract: Controllers for controlling heating, ventilating, air conditioning, and cooling (HVAC) systems are provided. The controllers include graphical user interfaces for user adjustment of system settings. The controllers also include communication interfaces for receiving climate data. In certain embodiments, the controllers govern operation of the HVAC systems based at least in part on the climate data. Further, the controllers may display information and alerts related to the climate data. The controllers also may govern operation of air treatment devices within the HVAC systems.

Abstract: The various embodiments disclosed herein relate to anti-sweat heater systems for refrigeration units. More specifically, certain embodiments relate to anti-sweat heater control systems having one or more controllers that operate anti-sweat heaters independently of each other.

Abstract: A cooling system including an evaporator to exchange heat with air, a frost detector installed on the evaporator to detect frost, and a control unit to determine whether a current time corresponds to a frost detection point, to control the frost detector to operate when the current time corresponds to the frost detection point, and to control a defrosting operation based on a frost detection signal from the frost detector. It is possible to accurately detect the amount of frost formed on the evaporator by executing the frost detection under constant frost detection environmental conditions.

Abstract: A method includes providing a standard supply of electrical power to a defrost heater during a standard defrost cycle for a refrigeration system of an appliance, detecting a high energy demand period during the standard defrost cycle, and enabling a reduced consumption of electrical power by the defrost heater in a low power defrost cycle.

Abstract: An energy saving defrost control system for reducing power consumption of an electromechanically controlled refrigerator is provided. The system includes a defrost timer adapted to control a compressor according to an established run time, a defrost heater control operatively connected to the defrost timer and configured to activate a defrost heater in response to a timeout by the defrost timer, a DSM module responsive to demand state signals from an associated utility indicative of at least a peak demand and off peak demand state, and a time delay latching relay having a timer and configured to switch to one of a low position and a high position based on the demand state signal.

Abstract: A refrigerator and a method of operating a refrigerator to determine the time at which to initiate a defrost cycle is provided. Changes in the voltage provided to an evaporator fan are used to determine and/or predict when to initiate a defrost cycle. Adjustments to the timing of the defrost cycle can be made based on known periods of peak energy demand and/or the increased costs associated with operating the defrost cycle during such peak energy demand periods.

Abstract: Methods and systems are provided for controlling a defrost unit for a vehicle. A prediction is performed as to whether condensation has formed against a surface of the vehicle. The defrost unit is automatically activated when it is predicted that the condensation has formed against the surface. Another prediction is made as to whether condensation has dissipated from the surface while the defrost unit is operating. The defrost unit is automatically deactivated when it is predicted that the condensation has dissipated.

Abstract: A defrost fan control device for a refrigerator is provided. The device comprises a container, a heat exchanger, a chamber, a suction pump, a condensate spraying device, an evaporation coil, and a blower. The suction pump is for sucking up the condensate from the container. The condensate spraying device is for spraying the condensate sucked up by the suction pump within the chamber. The evaporation coil is disposed around the condensate spraying device such that the condensate from the suction pump lands on an inner surface of the evaporation coil and evaporates the condensate. The blower is for inducing air flow within the chamber, whereby the evaporated condensate is exhausted from the chamber.

Abstract: A control device includes a microcomputer and a storage element. The microcomputer is configured to execute an inspection operation mode in which an air conditioner is operated in inspection process in a manufacturing site, and a normal operation mode in which the air conditioner is operated at an installation site. When the operation state of the air conditioner fails to satisfy predetermined conditions, the microcomputer is configured to confirm that there is an error, and abnormally stop the air conditioner. When the air conditioner is abnormally stopped, the microcomputer is configured to cause the storage element to store predetermined operation information obtained during a period until abnormal stoppage of the air conditioner and to store the operation mode being executed at the time of occurrence of the error in the air conditioner.

Abstract: An electronic defrost system consisting of a circuit board designed to implement defrost cycle of an air source heat pump outdoor coil during the off-cycle period. off-cycle is when the house thermostat is satisfied, heat pump is timed off for two minutes and then reactivated in regular defrost cycle if defrost sensor is calling for defrost. (Temp/off cycle). When sensor opens, heat pump will shut off for two minutes to allow pressure equalization. The automatic emergency heat is an option that can be selected. The automatic setting will activate the same circuit as the manual switch at the indoor house thermostat. Defrost control board designed to activate all heat strips during defrost cycle if desired.

Abstract: A method of analyzing a refrigeration system (1) comprising at least one compressor (4), at least one condenser (5) and at least two refrigeration entities (2), each comprising at least one evaporator (9). Based on information relating to the gas production by the evaporators (9) it is determined whether or not two or more evaporators (9) are running in a synchronized manner, i.e. are switching between an active and an inactive state at least substantially simultaneously. In case two or more evaporators (9) are running in a synchronized manner, the refrigeration system (1) may be controlled in order to desynchronize the evaporators (9). This may, e.g., be done by changing a cut-in temperature and/or a cut-out temperature for one of the corresponding refrigeration entities (2). Synchronization causes undesired variations in the suction pressure, and preventing synchronization therefore results in a more appropriate control of the refrigeration system (1). Reduces wear on the compressors (4).

Abstract: A cooling apparatus including a frost sensor to sense frost, a multiplexer having a first input terminal, to which the frost sensor is connected, and a second input terminal as a non-connected input terminal, a signal processor to subtract a signal input through the second input terminal from a signal input through the first input terminal, and to output a signal obtained by the subtraction, and a controller to detect an amount of frost sensed by the frost sensor, based on the output signal from the signal processor. It is possible to easily and accurately determine noise contained in a signal received from the frost sensor by determining, as noise, the signal received from the input terminal, to which the frost sensor is not connected, and subtracting the noise from the signal received from each input terminal, to which the frost sensor is connected.

Abstract: A heat pump is provided with an improvement while switching from heating/cooling mode to a defrost mode. Prior to initiation of a defrost mode, an electronic expansion device is moved to an open position such that refrigerant can migrate between the indoor-outdoor heat exchangers. When the operation of the defrost cycle is initiated, there is a lower likelihood and severity of flooded starts, as the refrigerant, under existing pressure differential at system shutdown, will move to the heat exchanger that will be downstream of the compressor in the defrost mode. Thus, no flooded start will occur on the subsequent compressor start-up. After completion of the defrost cycle, the electronic expansion device is again opened prior to return to operation in the conventional heating/cooling mode. In case subsequent starts are in an identical mode of operation, the electronic expansion valve is kept closed during shutdown to minimize cyclic performance losses.

Abstract: A method for defrosting an evaporator of a refrigeration sealed system, the system including at least one refrigeration compartment and a controller operatively coupled to a compressor, an evaporator, an evaporator fan and a condenser fan, wherein the method includes initiating a defrost cycle, operating the sealed system to prechill the refrigeration compartment, and selectively operating the evaporator fan and the condenser fan to raise a temperature of the evaporator.

Abstract: An object of the present invention is to provide a control system, an integrated control apparatus, and a control program that are capable of well maintaining freshness and quality of food articles, by reducing time for performing a recovery operation following a frost removing operation of cooling devices. In response to a start of the frost removing operation of a first showcase, an integrated control apparatus provides a second device controller (device control unit) with a “lower limit cooling instruction (increase instruction)” to increase the refrigerant supplied to a second showcase to an amount larger than that before the frost removing operation starts. In response to the “lower limit cooling instruction (increase instruction),” the second device controller (device control unit) increases the amount of the refrigerant supplied to the second showcase.

Abstract: Disclosed is a defrosting system and a defrosting method of a refrigerator, the system including an evaporator configured to reduce an ambient temperature by heat exchange through movement of refrigerant, a frost monitoring camera by photographing a state of frost adhered to the evaporator, a controller configured to grasp changes of an image captured by the frost monitoring camera to determine a defrosting start time, and a heat-generating unit configured to emit heat in response to a signal applied from the controller to remove the frost, whereby an unnecessary operation of a heat-generating unit is prevented by appropriately coping with an environment that flexibly changes according to an inner situation of a refrigerator and by accurately determining, by the controller, a start time and a completion time of defrosting operation for removing frost adhered to the refrigerator.

Abstract: A system and method for controlling automatic defrost of a refrigerator device are provided. The system adaptively moves the defrost cycle to low usage times based on an evaluation of compressor usage in a daily cycle.

Abstract: Methods, systems and computer readable code for controlling a defrost cycle of a refrigeration device are disclosed. According to some embodiments, a defrost command is issued to a defrost heater at a time determined at least in part by a total wasted energy parameter of the compressor for at least one time interval. In some embodiments, time interval includes a plurality of runtimes, and the total wasted energy parameter of a runtime is measured relative to a chosen reference runtime such as a minimum energy runtime after a defrost or an early runtime after a defrost. Optionally, a sequence of wasted energy parameters of the compressor for a sequence of time intervals is analyzed, and then a correction is performed on at least one wasted energy parameter.

Abstract: A refrigerator control method is provided that may efficiently perform a defrosting operation. The method includes performing a normal operation of a refrigerating storage room and a normal operation of a freezing storage room selectively or simultaneously, setting a variable defrosting period, which is varied according to set parameters including the relative humidity of external air, and performing a defrosting operation based on the set defrosting period.

Abstract: An adaptive defrost control for a frozen product machine implements an algorithm that utilizes various operating parameters of the machine to adaptively adjust the time interval between successive defrost cycles in a manner such that defrost cycles occur only on an as-needed basis. The adaptive defrost control minimizes the time during which the machine is in a defrost cycle, thereby maximizing the uptime of the machine during which frozen product can be prepared.

Abstract: A hot water storage tank (3) and a circulating path (12) coupled to the hot water storage tank (3) are provided. An operation is possible wherein low-temperature water, let out from a lower part of the hot water storage tank (3) and entering the circulating path (12), is heated and boiled up by a heat pump heating source for forwarding to an upper part of the hot water storage tank (3). A refrigerant circulating circuit of the heat pump heating source is provided with a defrost circuit (38) for supplying hot gas from a compressor (25) to an air heat exchanger (28). It is possible to perform a defrost operation for providing a supply of hot gas to the air heat exchanger (28), with a water circulation pump (13) of the circulating path (12) held in abeyance. The water circulation pump (13) is made active if the defrost operation has been continued for not less than a predetermined time period since the start thereof.

Abstract: An air conditioner for a vehicle includes a vapor compression refrigeration cycle switchable between a heat pump cycle and a cooler cycle, a heat core configured to heat air to be blown into a vehicle compartment by using coolant of an engine of the vehicle as a heat source, and a controller configured to control operation of the vapor compression refrigeration cycle. The controller controls the vapor compression refrigeration cycle to be operated as the cooler cycle so as to perform a defrosting control of the outdoor heat exchanger, and outputs an operation request signal to the engine, when the controller determines that the outdoor heat exchanger is frosted.

Abstract: A refrigerating air conditioning system is provided with a refrigerant circuit which includes a compressor 3, an indoor heat exchanger 6, a first pressure reducing device 10, an outdoor heat exchanger 11, and a switching device 4 for switching a direction of a refrigerant flow between heating and cooling modes for supplying heat from the indoor heat exchanger 6. In the system, a refrigerant temperature detection sensor 14c of the outdoor heat exchanger 11 and an outdoor air temperature detection sensor 14d are provided for determining a state of a frost formed on the outdoor heat exchanger 11. Two types of defrosting inhibition time values ?1 and ?3 are allowed to be set in accordance with a previous defrosting time ?2 for continuously performing heating operation.

Abstract: Based on a result of detection taken by the high-low pressure difference detection means (93, 97) for detecting a difference between a high and a low pressure of a refrigeration cycle, an estimate of whether there is leakage of refrigerant in an expansion valve (52) is made. Based on the result detected by the high-low pressure difference detection means (93, 97), a control means (81) sets a reference temperature (T3) to a value corresponding to the degree of refrigerant leakage in the expansion valve (52).

Abstract: A method to detect and respond to a coil condition in an HVAC system. The method includes calculating an initial airflow restriction value and a current airflow restriction value, which are compared. If the current airflow restriction value is greater than a first sum including the initial airflow restriction value and a first restriction factor, then a coil condition is preliminarily determined to be freezing and cooling in the HVAC system is stopped.