A vehicle climate control system has a control strategy which controls temperature of an evaporator in a refrigeration circuit to achieve a target temperature/relative humidity within a comfort zone which is defined by upper and lower temperature boundaries and upper and lower relative humidity boundaries. Several system embodiments are disclosed, including an all-electric system. All systems operate with improved efficiency.

Cooling of a battery pack of an electrified vehicle is performed with an optimized energy usage and with minimal impact on cooling of the passenger cabin. The battery is actively cooled by circulating coolant from the battery to a chiller of an air conditioning system when a battery temperature is above a predetermined power-limiting temperature. The battery is passively cooled by circulating coolant from the battery to a radiator when the battery temperature is between a first threshold and the power-limiting temperature and a difference between a battery coolant temperature and an ambient air temperature is greater than a predetermined difference. The battery is actively cooled using the chiller when the battery temperature is between the first threshold and the power-limiting temperature and the difference between the battery coolant temperature and the ambient air temperature is less than the predetermined difference.

There is disclosed a vehicle air conditioning device of a heat pump system which delays proceeding of frosting onto an outdoor heat exchanger, thereby eliminating or inhibiting deterioration of a heating capability due to the frosting. The vehicle air conditioning device executes a heating mode in which a controller lets a refrigerant discharged from a compressor 2 radiate heat in a radiator 4, decompresses the refrigerant by which heat has been radiated, and then lets the refrigerant absorb heat in an outdoor heat exchanger 7, and on the basis of a difference TXO=(TXObaseTXO) between a refrigerant evaporation temperature TXObase of the outdoor heat exchanger 7 in non-frosting and a refrigerant evaporation temperature TXO of the outdoor heat exchanger 7, the controller corrects a target subcool degree TGSC that is a target value of a subcool degree of the refrigerant in the radiator 4 in an increasing direction in accordance with increase of the difference TXO.

A thermal system includes a high temperature coolant loop thermally coupled to a heater core configured for thermal exchange with an airflow into a cabin of the vehicle, and an air conditioning (A/C) loop having a compressor, a condenser, a first expansion device for a heat exchanger, a second expansion device for a chiller, and a third expansion device for an evaporator. The high temperature coolant loop is thermally coupled to the condenser. A controller includes one or more processors and is programmed to perform a window fogging prevention operation by controlling a speed of the compressor such that (i) a coolant temperature at the heater core reaches a first predetermined target temperature, and (ii) a coolant temperature at the evaporator does not fall below a second predetermined target temperature.