Loud Noise from the AC
 

I have been an active reader but first time posting here. When I turned on the AC over the weekend, I got a loud fan noise coming from the fan. I took my car to the dealer for yearly servicing, they asked me if I park outdoor, I have an indoor garage so I said not frequently. They said this is a very common problem and there may be leaves in the AC vent and they want to charge me for cleaning it. Never had such problem with any other car that I owned before. If this really is the case, does this mean that there is a design flaw with these models?

Happened to me last year during the Fall, when the leaves are coming down. When I went for my Service A, they removed the blower and cleaned leaves out of it, however they did not charge me for it.
There is flaw in the design on GLB, and since GLB is very similar to GLA, I am guessing it is the same issue. The cabin filter is located after the blower, and there is no pre-filter like on GLC, so leaves, pine needles, etc. could be sucked in. Once inside, the blower becomes disbalanced and makes the noise on high fan setting, like you are inside the propeller plane. After it was fixed, I got some black plastic window screen in Home Depot, cut it to size and glued it over the intake openings under the hood. There are 4 of them on GLB, one main and 3 smaller ones, lower in the well. Have not had issue since, fingers crossed.

Hope this helps.

Thank you Vlad. I never thought there would e a design flaw like this and Mercedes would hold me accountable.

Can you post a picture of where that intake opening is? Much appreciated.

I marked up the picture from my GLB. There are 4 air intake openings. One large, on the right side of the picture could be clearly seen, however there are 3 more small intakes on the bottom groove of the plenum, which are hard to see and always fill with debris. I think that is where the majority of debris get sucked into the blower.

Thanks for the detailed markup, this explains alot.