Vehicle air conditioning system

A vehicle air conditioning system, comprising

• a heater core at which, when generating air-conditioned air for air conditioning of inside of a vehicle cabin, heat exchange is performed between a thermal transfer medium that is circulated during a heating operation of inside the vehicle cabin and the air-conditioned air;
• an outside air heat absorption unit that is configured to enable heat absorption from a thermal transfer medium that is input after circulating from outside air that is introduced, by the thermal transfer medium circulating through the heater core;
• a grille shutter that is disposed such that a grilled opening opened forward of the vehicle is openable and closeable, and that enables outside air ahead of the vehicle to be introduced into the outside air heat absorption unit by opening the grille opening;
• a first temperature detector for detecting a first temperature that is a temperature of the thermal transfer medium input to the outside air heat absorption unit;
• a second temperature detector for detecting a second temperature that is a temperature of the outside air introduced into the outside air heat absorption unit;
• and
• a control unit for performing control to open the grille opening by the grille shutter when the first temperature is lower than the second temperature during heating of an inside of the vehicle cabin.