A printing system comprises a print fluid deposition assembly, a media transport device, and an air flow control system. The print fluid deposition assembly comprises a carrier plate and a printhead to eject a print fluid through an opening of the carrier plate to a deposition region. The media transport device holds a print medium against the movable support surface by vacuum suction and transports the print medium through the deposition region. The air flow control system comprises an air supply unit comprising an airflow guide structure extending into the opening of the carrier plate, the airflow guide structure configured to flow air at a direction aimed under the printhead and at an oblique angle relative to the movable support surface. The air flow control system controls the air supply unit to selectively flow the air based on a location of a print medium relative to the printhead.