The present invention relates to an air conditioner system for a vehicle includes an air-cooled condenser mounted between a water-cooled condenser and an expansion valve to exchange heat of refrigerant discharged from the water-cooled condenser with air in order to further cool the refrigerant even though temperature of the refrigerant rises due to temperature rise of coolant supplied to the water-cooled condenser, thereby enhancing cooling performance because the refrigerant flows into an internal heat exchanger due to a drop in temperature of the refrigerant, preventing a temperature rise of the refrigerant discharged from the compressor because temperature of the refrigerant flowing into the compressor drops, and enhancing durability and stability of the air conditioner system.