W211 whining cabin sound
Thread Starter
Member
Joined: Dec 2015
Posts: 194
Likes: 12
2012 C350 Edition 1
W211 whining cabin sound
So here is something interesting i've noticed on my few months old W211.
When the cabin a/c or heating is not on, everything sounds normal.
The minute i turn it on and weather the a/c compressor is on or not i notice whining sound from what i can describe the area behind the steering wheel.
It changes with the rpms change. It is very faint but i hear it.
I thought it was the transmission but again if the fan is not on it's not there.
i removed the fan from under the glove compartment to clean it and looks like new and there it normal fan noise when on.
I then looked at the air circulation fan in the upper console and i can hear it running as a normal small fan, no whining.
then i tried hear the fan on the right hand side of the steering wheel opening and it doesn't sound like it's coming from there.
Is there another fan somewhere or inside the engine bay?
has anyone experienced this?
It's almost impossible to capture it on audio so you have to take my word for it.
Appreciate the feedback.
When the cabin a/c or heating is not on, everything sounds normal.
The minute i turn it on and weather the a/c compressor is on or not i notice whining sound from what i can describe the area behind the steering wheel.
It changes with the rpms change. It is very faint but i hear it.
I thought it was the transmission but again if the fan is not on it's not there.
i removed the fan from under the glove compartment to clean it and looks like new and there it normal fan noise when on.
I then looked at the air circulation fan in the upper console and i can hear it running as a normal small fan, no whining.
then i tried hear the fan on the right hand side of the steering wheel opening and it doesn't sound like it's coming from there.
Is there another fan somewhere or inside the engine bay?
has anyone experienced this?
It's almost impossible to capture it on audio so you have to take my word for it.
Appreciate the feedback.
MBWorld Fanatic!
Joined: May 2021
Posts: 2,524
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From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Perhaps looking at the parts diagram for the AC system, and understanding the location of the moving parts
Sedan: http://mbepc.net/1/fg/e/65h/211056#gsc.tab=0
Wagon: http://mbepc.net/1/fg/e/65j/211256/0/83/#gsc.tab=0
Sedan: http://mbepc.net/1/fg/e/65h/211056#gsc.tab=0
Wagon: http://mbepc.net/1/fg/e/65j/211256/0/83/#gsc.tab=0
Last edited by JCM_MB; Oct 29, 2021 at 10:26 AM.
MBWorld Fanatic!
Joined: May 2017
Posts: 2,290
Likes: 434
C320
So here is something interesting i've noticed on my few months old W211.
When the cabin a/c or heating is not on, everything sounds normal.
The minute i turn it on and weather the a/c compressor is on or not i notice whining sound from what i can describe the area behind the steering wheel.
It changes with the rpms change. It is very faint but i hear it.
I thought it was the transmission but again if the fan is not on it's not there.
i removed the fan from under the glove compartment to clean it and looks like new and there it normal fan noise when on.
I then looked at the air circulation fan in the upper console and i can hear it running as a normal small fan, no whining.
then i tried hear the fan on the right hand side of the steering wheel opening and it doesn't sound like it's coming from there.
Is there another fan somewhere or inside the engine bay?
has anyone experienced this?
It's almost impossible to capture it on audio so you have to take my word for it.
Appreciate the feedback.
When the cabin a/c or heating is not on, everything sounds normal.
The minute i turn it on and weather the a/c compressor is on or not i notice whining sound from what i can describe the area behind the steering wheel.
It changes with the rpms change. It is very faint but i hear it.
I thought it was the transmission but again if the fan is not on it's not there.
i removed the fan from under the glove compartment to clean it and looks like new and there it normal fan noise when on.
I then looked at the air circulation fan in the upper console and i can hear it running as a normal small fan, no whining.
then i tried hear the fan on the right hand side of the steering wheel opening and it doesn't sound like it's coming from there.
Is there another fan somewhere or inside the engine bay?
has anyone experienced this?
It's almost impossible to capture it on audio so you have to take my word for it.
Appreciate the feedback.
Thread Starter
Member
Joined: Dec 2015
Posts: 194
Likes: 12
2012 C350 Edition 1
It's it's not the fans. You're hearing the AC compressor through the lines. That's why the pitch changes with engine RPM, not fan speed. Turn the AC off but keep the fan on, wait about 3 minutes until the AC compressor is completely (it doesn't switch off instantly). Behold no more noise. Every time you start the engine even if the AC is switched off your AC compressor is running that's why you're hearing. Wait a few minutes with the AC switched off and the noise goes away. If you hit the big O button in the center of the climate control unit the noise goes away instantly because the AC compressor switches off instantly along with the fan. My 04 does it too.
ok
i will test this later.
what is the big O in the Center console? Is that off?
and if this is the case with the a/c compressor what is the fix? New compressor?
MBWorld Fanatic!
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From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
1 - Check codes for AC system
2 - Measure pressure on both sides,: high and low, using the appropriate procedure (discussed in other threads in the forum). Are they within the specifications?
3 - Perhaps worth reading https://www.mercedesmedic.com/diagno...mercedes-benz/
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Thread Starter
Member
Joined: Dec 2015
Posts: 194
Likes: 12
2012 C350 Edition 1
Ok, checked for codes and all is clear.
Your logic holds water on being the a/c compressor.
I will use statoscope to confirm.
So, looks like might be the a/c bearings (not the clutch) and wondering if i should tackle that next.
Your logic holds water on being the a/c compressor.
I will use statoscope to confirm.
So, looks like might be the a/c bearings (not the clutch) and wondering if i should tackle that next.
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MBWorld Fanatic!
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C320
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W211 E500 4Matic
Did you fix yours?
Senior Member
Joined: Aug 2014
Posts: 337
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From: Charlotte, NC
2005 E320 CDI, 2015 GLA 250
I get a strong whistling noise if I shut the rear air vents. The fan overpowers the front vents and they start whistling. When I open the rear vents, everything quiets down.
Peter
Peter
Member
Joined: May 2012
Posts: 98
Likes: 19
From: Orange County, CA
08 E350
Hey, I'm experiencing the same issue and it's driving me NUTS. The AC system was completely emptied yesterday, checked for leaks and brand new fresh refrigerant was put in. There is still that annoying whine behind the dash the moment I switch on the AC or blower. As soon as I hit the 0 - it goes away. It changes with RPMs so I was leaning towards bad AC compressor - mechanic told me mine is all good and he is almost certain it's something behind the dash.
Did you fix yours?
Did you fix yours?
MBWorld Fanatic!
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From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Hey, I'm experiencing the same issue and it's driving me NUTS. The AC system was completely emptied yesterday, checked for leaks and brand new fresh refrigerant was put in. There is still that annoying whine behind the dash the moment I switch on the AC or blower. As soon as I hit the 0 - it goes away. It changes with RPMs so I was leaning towards bad AC compressor - mechanic told me mine is all good and he is almost certain it's something behind the dash.
Did you fix yours?
Did you fix yours?
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W211 E500 4Matic
Please let me know if it fixes it for you.
After my last visit to the mechanic, when I last posted, it seems that the whine has reduced, but definitely hasn't gone away.
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W211 E500 4Matic
I definitely agree with you, but why would the sound change with RPMs?
Also, last year I took out the blower and got a professional shop to change the bearing and some kind of guides inside, as it was whining. So now I am confident that it's not the blower itself. Perhaps the blower resistor could make that whining sound? Someone else suggested that, but how would I test it, aside from buying a brand new one?
Also, last year I took out the blower and got a professional shop to change the bearing and some kind of guides inside, as it was whining. So now I am confident that it's not the blower itself. Perhaps the blower resistor could make that whining sound? Someone else suggested that, but how would I test it, aside from buying a brand new one?
MBWorld Fanatic!
Joined: May 2021
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From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
I definitely agree with you, but why would the sound change with RPMs?
Also, last year I took out the blower and got a professional shop to change the bearing and some kind of guides inside, as it was whining. So now I am confident that it's not the blower itself. Perhaps the blower resistor could make that whining sound? Someone else suggested that, but how would I test it, aside from buying a brand new one?
Also, last year I took out the blower and got a professional shop to change the bearing and some kind of guides inside, as it was whining. So now I am confident that it's not the blower itself. Perhaps the blower resistor could make that whining sound? Someone else suggested that, but how would I test it, aside from buying a brand new one?
MBWorld Fanatic!
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Posts: 2,524
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From: US
2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Member
Joined: May 2012
Posts: 98
Likes: 19
From: Orange County, CA
08 E350
RPMS of the blower are a function of the blower voltage regulator which is also sensitive to alternator voltage. Our 2008 E350 had that annoying noise that increased with RPM. I lubricated once, and it was ok a few months, but it came back. Replaced the blower 5 years ago, and so far so good.
I'll report back after I replace mine.
MBWorld Fanatic!
Joined: May 2021
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2008 E350, 2012 ML350, 2014 E350, 2015 ML350
Yes, but given that @dnikolov-211 said that the noise goes away when he turns everything off, and therefore the computer commands 0% AC compressor, is leading me to believe that he has the same issue as I do.
I'll report back after I replace mine.
I'll report back after I replace mine.
Member
Joined: May 2012
Posts: 98
Likes: 19
From: Orange County, CA
08 E350
I am not sure if the AC compressor would engage if the blower doesn't spin. I have to check Xentry if blower RPM is reported.
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W211 E500 4Matic
I am almost certain it won't, but I will try.
@JCM_MB Where is your sound coming from? I feel like on my car it's coming in from the centre of the dash.
Also, the whine starts to be more noticeable one the system was on for some time. For example if I drive 10 mins to a store, it is almost unnoticeable. But if I got for a 1-2 hour drive, then the whine/humming becomes very annoying inside the cabin.
@JCM_MB Where is your sound coming from? I feel like on my car it's coming in from the centre of the dash.
Also, the whine starts to be more noticeable one the system was on for some time. For example if I drive 10 mins to a store, it is almost unnoticeable. But if I got for a 1-2 hour drive, then the whine/humming becomes very annoying inside the cabin.
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W211 E500 4Matic
I can't believe I have FINALLY found someone with the same issue!
I have chatted with some people on Facebook groups and most of them resolved this whine by topping up refrigerant, which didn't actually work for me.
Well since you already got the compressor, I will wait for your feedback. If it's not that, I'll buy a brand new blower and report back.
I have chatted with some people on Facebook groups and most of them resolved this whine by topping up refrigerant, which didn't actually work for me.
Well since you already got the compressor, I will wait for your feedback. If it's not that, I'll buy a brand new blower and report back.
