Hi Everyone,

Just something I noticed now that the weather is getting colder. I always keep my climate control on "auto" at 72 degrees, on sync, and with the AC always on, as I know the dealer told me to keep it on all year. One thing I've noticed is when the car turns on, about a minute or two after, I hear a humming whistling sound when the air is blasting (warm air), lasting for about 10 seconds, and then goes away. My guess is it's the blend doors turning or something. But it sounds like someone is basically putting a piece of paper over their mouth and whistling. My mom's 2021 e350 does something similar, so I assume it's normal?

In the summer when the temperature was warm and hot, it didn't do it, my guess becuase the blend doors didn't have to turn that much? I don't know. But also, no issues with heat or anything, works great!

Has anyone noticed this?

I am glad to hear that I am not the only one experiencing this, also had a case where I turned it on full-blast on a hot day and the same whistling noise happens for about 10-15 seconds before going away.

Hahaha. Glad I'm not the only one either. Sounds like it's just something that happens.

The same with me. On speed level 1 it is giving such sound that it would have been on level 5. Unbelievable...

I had something like that in my GLE once. It turned out that the rear climate fan was set to max by accident and you could hear a loud noise in the front because of it. If you have 4-zone climate control check that. You can also check if some of the vents in the front or back are closed all the way, that could make it noisy as well.