Whistling noises from Dash vents on 2010 V6 vert
 

Just recently, I am experiencing whistling noises. After affair amount of troubleshooting, I have isolated the noise to the dash vents. When the fan is off, there is no noise. When the fan is high, the noise is louder. The noise only happens when the fan is exiting the dash vents. If it is either on defrost or coming at your feet, there is no noise. Even if there’s a combination of defrost and dash the noise disappears. I suspect that there a vent door that is not closing properly. Any help in diagnosing the problem or help with further troubleshooting would be appreciated.