A method for determining a heating load of a hybrid electric vehicle includes determining an SOC of a high-voltage battery through a controller, determining whether or not there is a heating request, based on a travel pattern input, through the controller when the SOC of the high-voltage battery is normal, calculating a required heating load according to the travel pattern input when there is the heating request, calculating an environmental condition according to an environment of the vehicle when there is the heating request, calculating a final heating load value through a combination of the calculated required heating load and the environmental condition of the vehicle, and adjusting a basic request engine torque according to the travel pattern input, taking into consideration the calculated final heating load value, and controlling driving of an engine based on the adjusted basic request engine torque.

Systems and methods can determine whether an air conditioning (AC) system of the vehicle is being operated under a maximum cooling condition. Responsive to determining that the AC system is being operated under the maximum cooling condition, it can be determined whether vehicle fluid temperatures meet associated predetermined thresholds. If none of the vehicle fluid temperatures meet the associated predetermined thresholds, a heater core valve can be switched to a closed position to reduce a flow rate of the coolant through a heater core. If one or more of the vehicle fluid temperatures meet the associated predetermined thresholds, the heater core valve can be switched to an open position to increase the flow rate of the coolant through the heater core. Such systems can force coolant to flow through the heater core to reduce vehicle fluid temperatures even when the AC system is being operated under the maximum cooling condition.

A control apparatus of a heat exchanging system according to the invention, decreases a duty ratio of the heater pump after connecting an engine water passage to a heater water passage, shutting off a predetermined water passage portion of the heater water passage, and increasing a duty ratio of an engine pump when the controls for shutting off the predetermined water passage portion, connecting the engine water passage to the heater water passage, decreasing the duty ratio of the heater pump, and increasing the duty ratio of the engine pump, are requested to be executed.

A control apparatus of a heat exchanging system according to the invention, decreases a duty ratio of the heater pump after connecting an engine water passage to a heater water passage, shutting off a predetermined water passage portion of the heater water passage, and increasing a duty ratio of an engine pump when the controls for shutting off the predetermined water passage portion, connecting the engine water passage to the heater water passage, decreasing the duty ratio of the heater pump, and increasing the duty ratio of the engine pump, are requested to be executed.

A control apparatus of a heat exchanging system according to the invention executes a control for activating a connection system to connect an engine water passage to a heater water passage and a control for increasing an engine pump duty ratio, and then executes a control for decreasing a heater pump duty ratio when the control for decreasing the heater pump duty ratio and the control for increasing the engine pump duty ratio are requested to be executed in order to control a core flow rate to a requested core flow rate and an engine flow rate to a requested engine flow rate after the engine water passage is connected to the heater water passage by the connection system.

A control apparatus of a heat exchanging system according to the invention executes a control for activating a connection system to connect an engine water passage to a heater water passage and a control for increasing an engine pump duty ratio, and then executes a control for decreasing a heater pump duty ratio when the control for decreasing the heater pump duty ratio and the control for increasing the engine pump duty ratio are requested to be executed in order to control a core flow rate to a requested core flow rate and an engine flow rate to a requested engine flow rate after the engine water passage is connected to the heater water passage by the connection system.

A control apparatus of a heat exchanging apparatus according to the invention executes a control for activating a connection system to connect an engine water passage to a heater water passage and then, executes a control for decreasing a heater pump duty ratio and a control for decreasing an engine pump duty ratio when the control for decreasing the heater pump duty ratio and the control for decreasing the engine pump duty ratio are requested to be executed in order to control a core flow rate to a requested core flow rate and an engine flow rate to a requested engine flow rate after the engine water passage is connected to the heater water passage by the connection system.

A control apparatus of a heat exchanging apparatus according to the invention executes a control for activating a connection system to connect an engine water passage to a heater water passage and then, executes a control for decreasing a heater pump duty ratio and a control for decreasing an engine pump duty ratio when the control for decreasing the heater pump duty ratio and the control for decreasing the engine pump duty ratio are requested to be executed in order to control a core flow rate to a requested core flow rate and an engine flow rate to a requested engine flow rate after the engine water passage is connected to the heater water passage by the connection system.

An air conditioning device for vehicles including an evaporator for cooling air; a heater core for heating air; and a unit case having formed therein a cooling space for accommodating the evaporator, a heating space for accommodating the heater core, and an air mixing space connected to the cooling space and the heating space. A pair of foot flow passages is in communication with the unit case, the pair of foot flow passages extending from the air mixing space and being arranged at a distance from each other in the width direction of the vehicle so as to sandwich a rear face flow passage in the width direction. The rear face flow passage and at least a part of each of the foot flow passages overlap each other when viewed in the width direction.

An air conditioning device for vehicles including an evaporator for cooling air; a heater core for heating air; and a unit case having formed therein a cooling space for accommodating the evaporator, a heating space for accommodating the heater core, and an air mixing space connected to the cooling space and the heating space. A pair of foot flow passages is in communication with the unit case, the pair of foot flow passages extending from the air mixing space and being arranged at a distance from each other in the width direction of the vehicle so as to sandwich a rear face flow passage in the width direction. The rear face flow passage and at least a part of each of the foot flow passages overlap each other when viewed in the width direction.