An upper opening portion (74, 75) and lower opening portion (76, 77) are arranged in a door body (13b, 14b) located below a side window (13a, 14a), and an air conditioning unit (15, 16) is arranged inside the door body (13b, 14b), and a rotary position of a scroll casing (62, 63) of a blower (56, 57) is selected so that air can flow from the lower opening portion (76, 77) to the upper opening portion (74, 75) at the time of air-cooling and air can flow from the upper opening portion (74, 75) to the lower opening portion (76, 77) at the time of heating.