Vehicle air conditioner

A vehicle air conditioner comprising:

• a case comprising an external air inlet and an internal air inlet;
• an external air door coupled to an inner side of the case and located adjacent to the external air inlet, the external air door comprising a seating groove formed in an inner side thereof;
• a first internal air door coupled to the inner side of the case and located adjacent to the internal air inlet, the first internal air door being configured to selectively contact the seating groove;
• and
• a linkage unit mounted on the case and configured for the external air door and the first internal air door to be coupled thereto, the linkage unit being configured to rotate the external air door and the first internal air door in conjunction with each other,
• wherein the first internal air door is inserted into the seating groove based on an opening degree of the first internal air door exceeding a set opening degree thereof.