An air conditioning unit for a vehicle has a casing, a heating heat exchanger, a first partition plate, a first opening, a second partition plate, a second opening, and a switching door. The casing has a face opening and a foot opening. The heating heat exchanger is arranged in the casing. The first partition plate partitions a downstream side of the heating heat exchanger in an airflow direction into a first passage and a second passage located below the first passage. The first opening is formed on a downstream side of the first partition plate in an airflow direction and communicates between the first passage and the second passage. The second partition plate is arranged on the downstream side of the heating heat exchanger and is formed with a third passage between the first partition plate and the second partition plate in the first passage. The second opening that is located on a downstream side of the second partition plate in an airflow direction and communicates between an upper side and a lower side of the second partition plate. The switching door opens or closes the first and second openings. The air in the third passage is guided toward the foot opening by the second partition plate and the switching door in an air conditioning mode in which the switching door opens the first opening and closes the second opening.