Air valves regulate the flow of compressed air within vehicle systems, primarily utilized in air suspension, braking, and pneumatic accessory control. These valves typically employ spools, diaphragms, or solenoids to open, close, or modulate airflow based on electrical or pneumatic signals. Common types include proportional valves for precise height control, quick-exhaust valves for rapid system response, and check valves to maintain pressure and prevent backflow. Construction materials commonly include aluminum alloys, brass, and reinforced polymers for durability and compatibility with compressed air systems. Failure modes often involve internal leaks, actuator malfunction, or solenoid failure, requiring replacement or rebuild for proper system function.