The symptom of a whistling noise in the cab that is caused by a misadjusted component is most likely due to which of the following?

• A. Cracked windshield
• B. Loose dash panel
• C. Bent door hinge
• D. Improperly adjusted driver's door

Answer: (D)

Airflow through gaps is the typical source of a whistle. If the driver's door isn’t adjusted correctly, it won’t sit squarely against the weatherstripping and door frame, leaving a small gap that air can rush through as the vehicle moves. That fast-moving air through the gap creates a high-pitched whistle, and it often changes with speed. Other noises, like a crack in the windshield or a loose dash panel, tend to produce rattles or creaks rather than a clean whistle tied to how the door seals. A door that’s out of alignment can cause sealing problems, but the direct cause of the whistle in this scenario is the door’s improper adjustment affecting the seal.