Air flow apparatus has at least one array of air channels, an air duct covering the array of air channels and being connected to the air channels, a fan arranged at the air duct for generating an air flow through the array of air channels, a cleaning device for the array of air channels arranged inside the air duct, the cleaning device including: a nozzle bar extending in front of the array of air channels and a nozzle manifold including a plurality of nozzles arranged along the nozzle bar and directed towards the array of air channels, wherein the nozzle bar is mounted to the air flow apparatus to be movable across at least a section of the array of air channels.