Downward-air-out type air conditioner indoor unit, control method and air conditioner

The invention provides a downward-air-out type air conditioner indoor unit, a control method and an air conditioner. The air conditioner indoor unit comprises an air deflector, and a rotating mechanism connected with the air deflector The air deflector can be pushed out or retracted into an air outlet; during the downward air-out process, the air deflector is driven to be pushed out and rotated toa fixed air-out position; when the air deflector is located at the fixed air-out position, a minimum distance M between the air deflector and the edge of the air outlet is larger than or equal to 10mm, and meanwhile, an included angle theta between an end edge tangent line of the air-out end of the air deflector and a horizontal direction is located between 10 degrees to 60 degrees; and the air-out end of the air deflector discharges air upwards. According to the downward-air-out type air conditioner indoor unit, the control method and the air conditioner provided by the invention, the wind resistance can be reduced, and a blown-out airflow can be maximally attached onto a wall surface of a ceiling to flow so as to form a wall attachment effect, so that the occurrence of the phenomenon that wind is directly blown to a human body is prevented to an extreme, cold air covers an indoor space to a maximum range, and the indoor comfort level is improved maximally.