The utility model relates to the technical field of automobile air conditioners and discloses an air conditioner core body expanding tube U-shaped support which comprises a support body and a locating pin arranged below the support body. The locating pin is used for mounting the support body on a base of a tube expanding machine. A U-shaped groove is formed above the support body. The U-shaped groove is the same as the lower end of an air conditioner core body heat exchanging pipe in shape. The U-shaped groove and the support body are a whole. The support body is made of nylon materials. According to the air conditioner core body expanding tube U-shaped support, the support body is made of the nylon materials, the self-lubrication performance of the nylon materials is used, so that when the tube expanding machine presses downwards, friction force between a pipeline and the U-shaped support is reduced, and accordingly the heat exchanging pipe enters a mould smoothly.