The Bendix AD-9 air dryer is a critical component in many heavy-duty trucks, ensuring that compressed air remains dry and clean before entering the brake system. When it fails, moisture buildup and contaminants can compromise safety. Fortunately, most common issues can be diagnosed and resolved with some basic knowledge and the right resources. Bendix manuals https://manuals.online/bendix contain the official Bendix instruction manual, service notes, and diagrams that provide step-by-step help for maintaining or repairing the AD-9 air dryer.One of the most frequent issues with the AD-9 is a purge valve that leaks air continuously after the compressor cuts out. This usually indicates that the purge valve assembly is dirty or the O-rings have worn out. To fix it, remove the purge valve and clean away any oil or debris. If cleaning doesn’t solve the problem, install a purge valve service kit, which includes new seals and springs.