An air conditioning system for a vehicle may include a cooling module including a cooling duct, a cooling-side inlet formed in a first end of the cooling duct, a cooling-side indoor outlet and a cooling-side outdoor outlet formed in a second end of the cooling duct, and an evaporator core provided in the cooling duct, a heating module including a heating duct, a heating-side inlet formed in a first end of the heating duct, a heating-side indoor outlet and a heating-side outdoor outlet formed in a second end of the heating duct, and a plurality of condensers provided in the heating duct, and a cooling blower and a heating blower respectively provided in the cooling duct and the heating duct, in which the plurality of condensers provided in the heating duct and the evaporator core provided in the cooling duct are coupled on a single refrigerant circuit.