KoryK

'03 E500 100k

Low whirring noise when climate control fan is on. Whir changes speed with the engine rpm. It's loudest from the center dash vent (half circle on the top center of the dash), and audible under the glove box, but not as loud. I've located and disconnected blower motor wire harness and whirring continues. Spent some time under the hood as well, back by firewall at its not coming from the engine compartment, or at least its not noticeable.

I don't have any problems with heat or cold or vents not working/blowing too hard. Basically everything works fine (as far as I can tell) except the little Gremlin in my dash is angry.

I've read on many threads that it could be the vent stepper motor(s) but nothing really matches what I'm experiencing, so before I tear apart my dash I'd like a second opinion. It doesn't click or thump at all and there is no high pitch whining, just low whir that follow RPM and especially louder after coming off of acceleration, then settles down a little quieter.

Any ideas?

bkhk

It could be audio interference coming out of the center dashboard audio speaker. If there is a problem with suppression, it will likely be engine RPM related.

KoryK

Holy Cow! I completely left out the possibility of speaker interference...makes total sense. Did some research and found this...

http://www.benzworld.org/forums/audi...-7-center.html

Looks like I've got a project after work!

Thanks!!!!

KoryK

So its not audio interference. While up in the dash disconnecting the center speaker I was closer to the noise and noticed the low whirring stronger when it sounded like the AC compressor kicked in and a valve opened up. So perhaps this is an AC issue? Any ideas on the probability of this being a fluid type or charge vs. hardware??

vettdvr

AC compressor is a full time operation no clutch by MB design so it doesn't cycle on/off as conventional a/c's

jimbo1763

I get the RPM-dependent buzz from my HVAC. It is not constant. When I turn off the fan altogether, it stops. Although it does not seem logical to me that the fan itself could be the culprit, that seems often to fix the matter on other posts that I have seen. The blower is not horribly expensive and is pretty easy to replace.

The usual sign of the blower having a problem is a chirping sound, and I don't have that. For now, I just turn up the radio and try to ignore it, but one of these days when it aggravates me enough I am going to change out the blower. It is throwing parts at the problem, I understand, but not at a huge cost.

DubVBenz

Does this mean it's a waste of effort to turn my A/C button off to conserve fuel or get a little bit more peppy response? I had an old 84 300SD, and me turning off the A/C before anticipating the need to accelerate became such a second nature that I still do it. In the later 126 diesels they put a switch that would automatically cut the compressor if you stepped on it hard enough...

hyrden

I have the same problem on my E500 2003. Would like to ask you or others with the same problem if you have found the solution?

hyrden

I have the same problem on my E500 2003. Would like to ask you or others with the same problem if you have found the solution.

HELP!

Low whirring noise when climate control fan is on. Whir changes speed with the engine rpm. It's loudest from the center dash vent (half circle on the top center of the dash), and audible under the glove box, but not as loud. I've located and disconnected blower motor wire harness and whirring continues. Spent some time under the hood as well, back by firewall at its not coming from the engine compartment, or at least its not noticeable.

tjts1

I'm surprised nobody has found a solution to this problem yet. My 04 E320 wagon does it as well. I can make it stop with the 0 button on the climate control. It's not the blower fan or the speaker. Def coming from the dash and it changes frequency with engine RPM. Any ideas?

cgmotorfactors

I have the Exact same problem, I thought it was the aux water pump just behind the slam panel, so i changed that but made no difference. Did you ever find the cause?

turbozeke418

I can't believe no one has found the cause of this issue. I have an 03 e500 with 198k and have had the same issue for a long time. My A/C system works perfectly but has a perpetual code 9201 (b1 0/6) evaporator temp sensor and 9370 (r22/3) heater booster hb/zh/zuh.

cgmotorfactors

Ac Gas was the cause of mine, Ac was still working , get it topped up

GHJA614

Your refrigerant was the issue? That seems odd.

Ahmed.attiq

I have exactly the same issue. Anyone care to share the solution ???