Test to Determine Root Cause(S)
Test to determine root cause(s)Before beginning any repairs, execute all the test steps to determine how many different conditions are present.
Tip: All tests are to be performed even if the customer only complains of the noise under one set of conditions. This will prevent repeat repairs.
Condition 1 Test
The noise is heard only when the interior of the car is cold and the blower speed is set within the range of medium to high (cold start mornings).
1. Check all front and rear air vents to ensure they are in the fully open position while performing all of the tests listed for condition 1-4. The back pressure created with any vent in the closed position can negatively affect the test results.
2. With the ignition on and the engine off, set the climate system to AUTO and set the temperature setting for the left side to (22°C) 72°F.
3. Press the left temperature adjustment knob for 3 seconds until the left and right temperature settings are synchronized.
4. Set the blower to level 7 and slowly turn the left temperature up from 72 until it reaches the HI setting.
5. Adjust the blower from level 7 to level 12 and listen for a whistling noise.
6. If the whistling noise is present, then slowly turn the left temperature from HI to LO.
7. Adjust the blower from level 7 to level 12 and listen for a whistling noise.
^ If the noise level is unchanged, then the vehicle is not affected by Condition 1.
^ If the noise disappears with blower settings of level 7-12 with a LO temperature setting, then this vehicle exhibits Condition 1. Continue with the remaining tests before attempting repair.
Condition 2 Test
The noise is heard only during the first 10 minutes of defrost mode with blower speeds of 6 or 7.
1. Set the air distribution to defrost and the left and right temperature settings to HI. Set the blower to level 6. The noise should be loudest at either blower level 6 or 7.
2. If the noise can be clearly heard, change the air distribution to panel vent mode.
^ If the whistling noise is still present, then the vehicle is not affected by Condition 2.
^ If the noise is gone in panel vent mode, the vehicle is affected by Condition 2.
Condition 3 Test
Noise is heard in panel vent mode at any temperature setting.
1. With the engine off, switch the air distribution to only dashboard panel vent mode, set the temperature to LO, and set the blower to level 7. Keep in mind that adjusting the temperature setting will automatically adjust the blower level in a manual blower override setting. If the blower speed has changed, then reset the setting to level 7.
2. If the whistling noise does not disappear at Auto and LO, then use the vent door thumb wheels to completely close both center dashboard vents.
^ If the whistling noise is still present with the vents closed, then the vehicle is not affected by Condition 3.
^ If the noise changes significantly or disappears, then the vehicle is affected by Condition 3.
Condition 4 Test
The noise is heard at any temperature setting, regardless of air distribution mode and only when the blower is set to within a range of medium to high.
1. Turn the ignition on. Ensure the left and right temperature settings are still synced and set to LO.
2. Set the system air distribution to panel vent and floor mode (Bi-Level Mode).
3. Slowly change the blower speed from level 6 to level 12 and listen for the whistling noise. If a whistling noise is heard while changing the levels, keep the blower set to the level in which the noise is heard the loudest.
4. Slowly change the temperature setting from LO to HI while maintaining the same blower speed. You may need to adjust the blower speed back after adjusting the temperature setting because the blower speed may automatically change while adjusting the temperature setting.
^ If the noise becomes less noticeable or disappears completely, the vehicle exhibits Condition 4.
^ If the noise is unchanged, the vehicle does not exhibit Condition 4.
If all the tests are performed and a proper repair cannot be identified, then please open a new ticket with the Audi Technical Assistance Center to ask for further assistance.