A vehicular air conditioning system includes: an intake part including an intake door configured to open an outdoor air inlet to introduce an outdoor air in an outdoor air mode, open an indoor air inlet to introduce an indoor air in an indoor air mode, and control an opening degree of the outdoor air inlet or the indoor air inlet, and a blower configured to suck the indoor air or the outdoor air through the indoor air inlet or the outdoor air inlet and blow the indoor air or the outdoor air into a vehicle interior; and a control part configured to control a rotational speed of the blower according to an air flow rate level of the air conditioning system.