Flows inside a passenger compartment of a 1/5 scale model vehicle have been simulated by using a general purpose FVM code, TURBO-3D. Three HVAC modes of heating, air-conditioning, and defrosting are simulated by defining three different inlets. Comparisons are made with the published experimental and computational results, giving a good agreement. A method of predicting the defrosting contours on the wind shield is also proposed in the present study, which enables design modifications in design stages.