[hoon]

Hi guys, my two week old F31 is making a weird and very very annoying high frequency noise from the vents. it sounds like very high pitch bell ringing.
the noise occurs when the engine is on and fans are on. and it increases significantly as rpm passes 1200...
weirdly, the noise goes away when i press the AC button or turn the fan completely off. anyone of you had had this issue? Thanks..

Link: the noise is clear at 00:30

[gomichaelkgo]

Sounds like a faulty HVAC fan to me!

[ajfriedm87]

Had a problem like that on a truck of mine, it was the bearing on the fan. The sound is probably always there, just different vent settings make it more or less prominent in the cabin (IE when you put AC on or not). Does the sound change as you raise and lower fan speed? IF so- bearing in HVAC fan.

[hoon]

hmm.. i dont think the sound increases as i change the fan speed.
yesterday i discovered(?) something new about this noise. you know the temperature thumb knob at the center? the more i move the thumb knob to the left (more blue), the sound becomes very prominent, and less so if I turn it the other way (more red)... .. maybe it really is faulty HVAC components..

[ft1330]

cant hear anything abnormal in the video. Air going through vent is bound to make some noise...

[ajfriedm87]

Originally Posted by hoon

hmm.. i dont think the sound increases as i change the fan speed.
yesterday i discovered(?) something new about this noise. you know the temperature thumb knob at the center? the more i move the thumb knob to the left (more blue), the sound becomes very prominent, and less so if I turn it the other way (more red)... .. maybe it really is faulty HVAC components..

Im sure someone on here has the schematics, but like I said if you can adjust the air mix or fan speed to alter the sound, theres some moving part in there putting out noise that you are just diverting around. So once again I blame the fan bearing

[hoon]

Thanks guys, I'm going in to the dealership on tuesday.. hopefully they'll be able to figure something out..

[daberlin]

Originally Posted by hoon

Thanks guys, I'm going in to the dealership on tuesday.. hopefully they'll be able to figure something out..

Be very curious as to what you uncover. I have the EXACT same noise and even though I can't hear it above the radio, etc., knowing it is there is driving me bonkers. BTW, I still hear this sound even if the fan is completely turned off. I plan on calling the dealer and scheduling an appointment. First time bringing the car in for an issue.

Update - booked in Valencia BMW at noon today.

[The.Lows]

Up !

I have the exact same noise on the car that I just bought (April 2014 F31 335i xdrive).

Did you guys find out ? Or you may as well just have sold your car by now

[rugina]

hello...found someone the problem?

[kingmonkey8]

Most likely the HVAC fan bearing has gone dry.
Same issue with previous generation BMW's. You can try lubricating the bearings. Not sure how accessible it is.on the F30.

[deviantspeed]

I hear it. Faulty fan on a 2017 VW I had I for a few thousand miles, dealer said they all sound that way. Same high pitched noise.

I said nope, never sounded like this new. They said there is nothing they can do and literally walked away. Same with the tranny whine and the THUNK noise when starting in reverse. Oh and I was very nice, too. I was literally thinking WTF VW, so I came back to BMW. Couldn't be happier.

Usually BMW service is MUCH better and more attentive. Let's hope for the best for you, My older 2013 didn't do this either.

[rlmesq]

Sometimes it can be as simple as a piece of paper or a leaf stuck in an air duct.

[The Kurgan]

Mine made the same noise, it was leaves and maple keys and other organic matter in my blower motor. Easy to access under the hood. I also pulled the cabin filter and alot of leaf debris fell out on the carpet.

[MetzgerMeister]

My f30 330d is making this noise. I bought a brand new blower motor and it didn’t solve the problem. Next step is the bearing on the front of the AC compressor but I don’t see how that could travel all the way into the cabin. It’s not leaves or anything stuck in the fan.

The noise is there when AC is on and when it’s off, no changes in the hot/cold settings make any difference at all. It’s strange because the AC pulley is always running as opposed to only when the AC is turned on.

It only goes away when the fan is completely turned off.

[MetzgerMeister]

I don’t know if anyone is following this thread or not but Imma post anyway

I made another discovery tonight (don’t know why I didn’t do this until now) but with the engine off I ran the fan on normal and with aircon on and there was no noise coming through the vents at all. Then I turned the engine on and the noise appeared instantly. Engine off again and no noise.

Therefore there’s nothing wrong with the blower motor or ac compressor. It’s just down to vibration acoustics coming in through the vents. The joys of owning a diesel!

[Moontan]

Originally Posted by MetzgerMeister

I made another discovery tonight (don’t know why I didn’t do this until now) but with the engine off I ran the fan on normal and with aircon on and there was no noise coming through the vents at all. Then I turned the engine on and the noise appeared instantly. Engine off again and no noise.

You do know that the AC compressor doesn't kick in with the engine off?

[MetzgerMeister]

Didn’t know that at all actually

[Maxgo]

Hi, wich was the "dealer" solution for those of you?

[Maxgo]

Well, I can also add more videos to this investigation.

The sound while driving:

https://www.youtube.com/watch?v=TbKenCPddOI

Operating the flaps, you can see that when directs to the footwell disappear or minimize

https://www.youtube.com/watch?v=jLWw0MtcRZA

This is the technical test, this proves that I'n not crazy, analyzing the waves, you can clearly see when the different operations are performed, first the blower is off, one band will disappear, and second, when the flaps are completely close, the stupid sound its not entering the car anymore. Around 1800 Hz...

https://www.youtube.com/watch?v=slJpqGHjymw

When you go outside the car, you can also ear it, it is resonating somewhere, because if you move to different positions, you can ear it also, that means that is not coming necesary from the front side right archwheel, where the video was recorder.

https://www.youtube.com/watch?v=ZLx1lYX6uI8

and yes, the stupid frequency is there, in this case at around 2100HZ...




Hope this helps to describe the issue!

[The@Thing]

Did you solve this problem ? Please help me

[MetzgerMeister]

It's actually the low pressure AC hose vibrating in the engine bay and this noise comes through the vents. BMW have a metal weight on these hoses from factory from a certain year (I think it's 2015 or 2016 here in Europe).

You can buy this weight from BMW:

Additional Weight - 64-5-39-322-952
Clamp - 07-12-9-952-119

It's an easy DIY but needs to be done from underneath the car.

Check - SIB 64 01 14