Should the Activated Carbon Side of the Cabin Air Filter Face Up or Down?

[AlainaFitz]

Whether the activated carbon side of the cabin air filter should face up or down depends on the direction of the blower's airflow: if the air blows upward, the activated carbon side should face downward; if the air blows downward, the activated carbon side should face upward. Activated carbon has strong adsorption properties, which can trap odors from the air onto the cabin air filter, filtering them out before the air enters the vehicle. The effects of a dirty air filter include: 1. Reduced filtration efficiency, leading to severe wear in the engine cylinders; 2. Incomplete combustion of gasoline, increased carbon buildup in the throttle body, resulting in unstable idling, black smoke from the exhaust pipe, and abnormal engine vibrations; 3. Blockage, causing insufficient air intake into the engine.