No one ever wants to hear strange noises coming from their car dashboards, but sometimes drivers start up their cars to hear bizarre whistling sounds suddenly coming from the vents. This can result in alarm for the driver, who now has to deal with an annoying sound that could cost an unknown amount to fix — but all is not as bad as it seems. A couple of really simple issues that can make your car's ventilation system sound horrible are more common than you may realize.

The Vent on the Far Side of the Dashboard

If you start your car and turn on the fan/heater/air conditioner and you hear a whistling sound, it means something in the ventilation system has closed off or severely reduced the airflow. That could be serious, but before you resign yourself to a high repair bill, check the vents on the dashboard, especially if you just took the car in for work, had someone sitting in the passenger seat in front, or moved items around in that area, including packages and windshield sunscreens.

If you or someone else hits the vent, such as when you removed a lot of grocery bags from the front passenger seat, you can send the vent lever that closes and opens the vent into the closed position. The whistling you hear is air trying to get through the now-closed slats of the vent. The reason this surprises many people is that the vent is often forgotten, especially by those who tend not to drive with passengers. You could have been wrestling with a windshield sunshade and accidentally knocked the vent into the closed position, for example. If you see the vent is not fully open, move the lever into the fully open position, and chances are that the noise will stop.

Glove Compartment Paper

If the noise doesn't stop, there's one more possible simple cause. If you carry a lot of paper in your glove compartment — loose receipts, registration forms, and so on — those can slip behind the compartment door. If you open the glove compartment, remove all the items in it, and then slowly close the door, you'll see that the back of the compartment in many cars is actually open — there's no full back that holds the paper in. There is a partial one, but you'll still see a gap in many cars. Papers that fall behind the compartment can fall into airstreams near filters and create a whistling sound.

Take a small mirror and a flashlight and try to look in that gap and see if you can see paper. Glove compartment doors are removable (it varies by make, so search out make-specific videos or bring the car into a repair center), and you can fish out the paper.

If there's no paper, bring the car into an auto repair shop and ask them to look at the ventilation system. You don't want to deal with a loud whistling sound every time you drive the car.