A vehicle air-conditioning system for achieving a comfortable blowout state of conditioned air at all times both with respect to air-conditioning load factors which change frequently, like solar radiation strength, and with respect to air-conditioning load factors which change slowly, like passenger compartment temperature, by automatic control of grill louver swing control times corresponding to different air-conditioning loads. For example, when it can be estimated that solar radiation is incident on a driver side or passenger side front or rear seat occupant, oscillating driver side and passenger side center louvers are paused at a swing end of the occupant estimated to be exposed to solar radiation for a time that corresponds to the amount of cooling load. Therefore, it is possible to direct conditioned air at an occupant exposed to sun and thus improve the comfort of occupants upon whom sun is incident.