A ventilation unit for a motor vehicle comprises a housing (30) with air ducts through which air is introduced into the interior space of the vehicle through openings in the dashboard. An aspiration pipe (40, 50) is arranged in the housing and comprises an outlet slot (41, 51) arranged in such a way that it is exposed to the air stream that flows out of the openings in the dashboard. The air flow generated by the air stream that flows past the outlet slot aspirates hot air from inside the aspiration pipe, mixing it with the outflowing air stream.