The invention relates to a method for operating a climate-control system (12) for a vehicle (10). According to the invention, total energy efficiencies are determined for a group of operating strategies for the air-conditioning system (12) and an operating strategy with the greatest total efficiency that fulfills the heating output requirement (44) that has been determined, is selected.

A refrigerating and air-conditioning apparatus performs, even during a heating operation under air conditions leading to formation of frost, a defrosting operation while simultaneously continuing a heating operation and that improves comfort through heating by ensuring an appropriate amount of ventilation. A plurality of refrigeration cycles that are capable of independently performing a heating operation and a defrosting operation, are provided. A ventilation damper of an indoor unit in which a refrigeration cycle that performs a defrosting operation is installed is closed during a defrosting operation, and a ventilation damper of an indoor unit in which a refrigeration cycle that performs a heating operation is installed is controlled to achieve a required amount of ventilation corresponding to the indoor ventilation state.

A vehicle air conditioner is capable of selecting and changing an optimum operation mode so that a desirable air conditioning performance can be exerted on conditions such as an environment and a set temperature. A controller changes and executes at least one of a heating mode, a dehumidifying and heating mode, a dehumidifying and cooling mode, and a cooling mode. In the dehumidifying and heating mode, the controller shifts to the dehumidifying and cooling mode on the basis of a situation where heat absorption in a heat absorber (9) runs short or heat radiation in a radiator (4) becomes excessive, and also in this dehumidifying and cooling mode, the controller shifts to the dehumidifying and heating mode on the basis of a situation where the heat radiation in the radiator (4) runs short.

A vehicle air conditioner which can enlarge an effective range of a dehumidifying and cooling mode to realize comfortable air condition in a vehicle interior. A controller changes and executes at least one of a heating mode, a dehumidifying and heating mode, a dehumidifying and cooling mode, and a cooling mode. In at least the dehumidifying and cooling mode, the controller controls a capability of a compressor (2) on the basis of a temperature of a heat absorber (9), and controls a valve position of an outdoor expansion valve (6) on the basis of a temperature or a pressure of the radiator (4), and executes a radiator temperature prior mode to enlarge the capability of the compressor (2), in a case where heat radiation in the radiator (4) runs short.

There is disclosed an air-conditioning device of a so-called heat pump system which acquires comfortable heating in a vehicle interior by preventing or inhibiting frost formation to an outdoor heat exchanger. In a vehicular air-conditioning device 1, a controller calculates a requested refrigerant evaporation temperature in non-frosting TXObaseQtgt which is a refrigerant evaporation temperature of an outdoor heat exchanger 7 when a required heating capability Qtgt as a heating capability required for a radiator 4 is realized in non-frosting of the outdoor heat exchanger 7, and the controller controls heating by the radiator 4 and heating by a heating medium-air heat exchanger 40 of a heating medium circulating circuit 23 on the basis of the requested refrigerant evaporation temperature in non-frosting TXObaseQtgt and a frost point Tfrost to achieve the required heating capability Qtgt without causing frost formation to the outdoor heat exchanger 7.

A heat pump air conditioner assembly for an electric vehicle and a control method thereof, and an electric vehicle with the heat pump air conditioner assembly for the electric vehicle are provided. The heat pump air conditioner assembly includes a heat pump air conditioning system and a HVAC box body. An in-vehicle heat exchanger of the heat pump air conditioning system is located in the HVAC box body. An auxiliary heater is also arranged in the HVAC box body. The auxiliary heater is located at a leeward side of the in-vehicle heat exchanger. The heat pump air conditioning system is provided with a defrosting branch connecting with a refrigerant outlet of an external heat exchanger and a suction port of a compressor. When the heat pump air conditioning system is in a defrosting mode, the HVAC box body supplies air to the vehicle, the auxiliary heater is turned on.

A method of controlling the refrigerant pressure in an ambient heat exchanger of a refrigerant circuit, particularly a heat pump circuit, for vehicles, in which the current temperature and the current humidity of the ambient air is measured, the current dew point temperature of the ambient air is determined from the measured temperature and humidity, and if the ambient air temperature is below 0° C. the refrigerant pressure in the refrigerant circuit is controlled by adjusting the rotational speed of a refrigerant compressor of the refrigerant circuit, the flow cross-section of a controllable expansion element of the refrigerant circuit and/or the ambient air volume flow flowing around or through the ambient heat exchanger, such that the temperature of the ambient heat exchanger is greater than the dew point temperature.

Methods and systems for de-icing an exterior heat exchanger of a vehicle's heat pump are presented. In one example, a positive temperature coefficient (PTC) heater provides heat to refrigerant that de-ices the exterior heat exchanger. In some examples, an additional PTC heater provides heat to engine coolant to warm a vehicle's passenger cabin when the vehicle's exterior heat exchanger is being de-iced.

A vehicle air conditioning apparatus includes an outdoor expansion valve controller configured to control an evaporating temperature of a refrigerant in a heat exchanger by regulating an opening of an outdoor expansion valve during a heating and dehumidifying operation, an evaporating temperature control valve provided in a refrigerant flow passage to an output side of the heat exchanger from which the refrigerant is discharged, and configured to control the evaporating temperature of the refrigerant in the heat exchanger by regulating an amount of the refrigerant flowing through the refrigerant flow passage, a temperature detector configured to detect a temperature of the refrigerant in the heat exchanger, and a control changer configured to change control of the evaporating temperature of the refrigerant in the heat exchanger from by regulating an opening of the outdoor expansion valve to by regulating an opening of the evaporating temperature control valve.

A method for defrosting a heat exchanger of a refrigeration circuit is provided. The method includes monitoring a compressor suction parameter at a suction line to a compressor of the refrigeration circuit. The method also includes determining a compressor suction parameter threshold. Also, the method includes initiating a defrost mode of the refrigeration circuit when the compressor suction parameter is less than or equal to the compressor suction parameter threshold.