An engine compartment arrangement for an agricultural harvester comprises an engine (10), a diesel particulate filter (12) coupled to the engine (10) to receive and filter hot exhaust gases therefrom, a fan (14), a radiator (16) disposed in a cooling airflow path in front of the fan (14) and coupled to the engine (10) to cool said engine (10), a cleaning air duct (18) having a first end (20) disposed immediately behind the fan (14) to receive a portion of the air ejected from the fan (14), and having a second end (22) disposed adjacent to the top of the diesel particulate filter (12) to exhaust a jet of the ejected air at a sufficient speed and in sufficient volume across the top surface (24) of the diesel particular filter (12) to prevent an accumulation of agricultural debris on top of the diesel particulate filter (12).