An air-conditioning system of a motor vehicle having refrigerant circulation and coolant circulation. Refrigerant circulation comprises a compressor, a refrigerant-coolant heat exchanger operable as condenser/gas cooler for heat transfer between the refrigerant and the coolant, a first expansion element and a first refrigerant-air heat exchanger for conditioning the inflowing air for the passenger compartment. Coolant circulation is developed with a conveying device, a first coolant-air heat exchanger for heating the inflowing air for the passenger compartment, a second coolant-air heat exchanger and the refrigerant-coolant heat exchanger. Refrigerant circulation also includes a second refrigerant-air heat exchanger, operable exclusively as evaporator. Upstream of the second refrigerant-air heat exchanger in the direction of flow of the refrigerant, a second expansion element is disposed. The second expansion element and the second refrigerant-air heat exchanger are disposed within a first flow path. A method for operating the air-conditioning system.

A cooling device for, for example, a cooling object has a refrigerant circuit with an evaporator, in which a cold air flow for the cooling object exchanges heat with the refrigerant, and a defrosting system for de-icing the evaporator. The defrosting system is controlled according to the degree of icing of the evaporator. The degree of icing of the evaporator is determined by the control unit of the defrosting system on the basis of the temperature of the cold air flow from the cooling object to the evaporator, the temperature and/or the operating pressure of the refrigerant upstream of the evaporator and at least one operating parameter of the compressor.

In order to provide a method for de-icing a heat exchanger of a motor vehicle, which prevents large amounts of melt water from a defrosting process running onto the floor or the road beneath the motor vehicle, freeze again and pose a risk of injury to pedestrians, in a method for defrosting a heat exchanger of a motor vehicle, in which, for a heat exchanger arranged in a motor vehicle, a defrosting process for removing a layer of frozen water or frost formed on a surface of the heat exchanger is carried out, the defrosting process comprising heating the surface, and melt water being produced, it is proposed that the amount of melt water discharged onto a local region of a floor beneath the motor vehicle is limited to a maximum value.

A method for defrosting an external heat exchanger, operated as an air heat pump evaporator, of a cooling system for a motor vehicle. The cooling system includes a refrigerant compressor connected to a primary and secondary section; an external heat exchanger; an evaporator; a heating register; a primary section valve which is closed in the air heat pump operation; and a secondary section valve which is open in the air heat pump operation. The method includes closing of the secondary section valve; opening of the primary section valve, so that refrigerant flows directly from the refrigerant compressor to the external heat exchanger; and setting an inlet-side pressure level of the refrigerant on the external heat exchanger to a target pressure which corresponds to a condensation temperature (Tkond) of the refrigerant in the range: 2° C.≤Tkond≤20° C., in particular 4° C.≤Tkond≤10° C.

There is provided a vehicle air conditioning device of a heat pump system which improves comfortability when changing to heating only by an auxiliary heating device. The device includes a heating medium circulating circuit 23 to heat air to be supplied from an air flow passage 3 to a vehicle interior, and when shifting to the heating of the vehicle interior only by the heating medium circulating circuit 23 in a heating mode, a controller executes a shifting control to increase a heating capability of the heating medium circulating circuit 23 prior to stopping a compressor 2 and decrease a heating capability of a radiator 4 in accordance with the increase of the heating capability of the heating medium circulating circuit 23.

An arrangement for de-icing a heat exchanger includes an air guiding housing and at least one fan. The air guiding housing is configured to take in an air from an outside of a motor vehicle through an inlet opening and to discharge the air from an outlet opening. The fan is positioned between the inlet opening and the outlet opening inside the air guiding housing and is configured to circulate the air in the air guiding housing. The heat exchanger is positioned between the inlet opening and the outlet opening inside the air guiding housing and allows the air to pass therethrough, thereby being configured to cool the air. The inlet opening and the outlet opening each are configured to be closed. The air guiding housing is configured to cause a circulation flow therein when the fan is operated while the inlet opening and the outlet opening are closed.

A vehicle air-conditioning device is provided which is capable of eliminating inconvenience due to a reduction in heating capability when changing from heat absorption from outdoor air to heat absorption from a heat medium. A heat-generating equipment temperature adjusting device 61 has a heat medium heating heater 66 and a refrigerant-heat medium heat exchanger 64. The vehicle air-conditioning device has first and second heat medium heat absorption/heating modes to let a refrigerant discharged from a compressor 2 radiate heat in a radiator 4, decompress the refrigerant from which the heat has been radiated, and then let the refrigerant absorb heat in the refrigerant-heat medium heat exchanger. When the temperature of the heat medium is a predetermined threshold T1 or less upon changing from a heating operation to the first and second heat medium heat absorption/heating modes, the heat medium is heated by the heat medium heating heater before the changing.

A cooling and heating system for a motor vehicle comprises a heat pump, a controller, a low temperature radiator in thermal communication with the heat pump, a passenger cabin heat exchanger in thermal communication with the heat pump, and a defrost system comprising a bypass coolant loop in selective fluid communication with the low temperature radiator. When in the heating mode, the controller opens a solenoid valve and activates a coolant heater in the bypass coolant loop upon detecting operation of the heat pump outside of a predetermined normal operating range and upon detecting an ambient temperature below a predetermined temperature. The controller de-activates the coolant heater upon detecting operation of the heat pump within the predetermined normal operating range. The controller may also de-activate close the solenoid upon detecting operation of the heat pump within the predetermined normal operating range.

A thermal management system for a passenger cabin of a hybrid vehicle includes a refrigerant loop in fluid communication with a compressor, a condenser, and a chiller. A main cabin evaporator is in fluid communication with the refrigerant loop. A first valve is configured to regulate refrigerant flow through the main cabin evaporator. A temperature sensor disposed at the main cabin evaporator is configured to output a signal indicative of a main cabin evaporator temperature. An auxiliary evaporator is in fluid communication with the refrigerant loop. A second valve is configured to regulate refrigerant flow through the auxiliary evaporator. A controller is programmed to, in response to the main cabin evaporator temperature being less than a threshold while the main cabin evaporator is operated with the second valve closed, open the second valve to cycle refrigerant through the auxiliary evaporator to increase the main cabin evaporator temperature.

There is disclosed a vehicle air conditioner device of a so-called heat pump system to accurately perform efficient and comfortable heating of a vehicle interior. The vehicle air conditioner device includes a heating medium circulating circuit 23 which heats air to be supplied from an air flow passage 3 to a vehicle interior. A controller calculates a required heating capability TGQhtr of the heating medium circulating circuit to complement a shortage of an actual heating capability Qhp to a required heating capability TGQ of a radiator 4. The controller calculates a decrease amount ΔQhp of the actual heating capability Qhp from a difference ΔTXO between a refrigerant evaporation temperature TXO of an outdoor heat exchanger 7 and a refrigerant evaporation temperature TXObase in non-frosting, and adds the decrease amount ΔQhp to the required heating capability TGQhtr to execute the heating by the heating medium circulating circuit.