This retaining washer secures the air-conditioning compressor shaft within the cab climate-control system. It sits between the compressor pulley and the front housing, preventing axial movement of the shaft under belt tension and compressor cycling loads. A missing or worn washer allows shaft endplay, which can cause compressor seal leakage and loss of refrigerant. The original AGCO part is machined to the same thickness and inner diameter as the factory washer, so the compressor stack height and bearing preload remain within specification. On reinstallation, verify the washer is seated flat against the shoulder before fitting the retaining clip.