A HVAC system includes a housing including at least one wall, an air flow path defined at least partially by the at least one wall, and a door disposed in the air flow path, where the door is configured to i) block a flow of air through the air flow path when the door is in at least one closed position, and ii) allow the flow of air through the air flow path when the door is in a position other than the at least one closed position. A gap is formed between the door and the at least one wall when the door is in the position other than the at least one closed position. The HVAC system further includes a noise-reducing feature defined on at least a portion of the at least one wall. The noise-reducing feature configured to break up, into several smaller structures, an air flow structure formed when air flowing through the gap contacts an end of the door, thereby reducing air vibration in the gap and reducing noise of the HVAC system during operation thereof.