Disclosed herein is an air conditioning system for a vehicle, in which an air conditioning unit having noise inducing unit is arranged at an engine room based on a dash panel and a distribution duct for distributing air to the interior of the vehicle is arranged in the interior of the vehicle based on the dash panel, thereby reducing noise and vibration in the interior of the vehicle, securing visibility and enabling a worker to easily access the air conditioning system for follow-up service because the air conditioning unit causing noise is arranged inside the engine room, and enhancing passengers' convenience by maximizing the interior space of the vehicle in comparison with the conventional air conditioning systems because only the distribution duct is arranged in the interior of the vehicle.