DRBC43AMG

Took my sexy lady for a drive and she started doing a very high pitch whine. It could be accelerator related as it seems to increase and decrease when pushing or letting off the pedal, sometimes at around 2000 rpm and stopping at 3000 rpm.

I didn't have time to connecter my Carsoft diagnostic software coming home tonight, but will do so tomorrow.

I may do a quick video to show you what I'm talking about.

She drives otherwise perfectly apart from the whine.

Any ideas what it could be?

cm60k

Whine from front or back..?

,,ZAYED,,

DRBC43AMG

It seems to be from the front. Thought it was the radio unit but it was switched off.

cm60k

Is it from inside or outside the car..?

,,ZAYED,,

DRBC43AMG

Difficult to say. I was driving with the windows closed and A/C on

cm60k

If it from outside, could be bad wheel bearing,,

but from inside, might be something wrong with heating/ventilation system..!!

,,ZAYED,,

Sulaco

could still be radio, even though it's off. my old C280 did it for years when the amplifier started to have dried out capacitors. the amps in the C43 are almost identical. I'm shocked my current one still works. The amp is what powers all the speakers, so if it has a short or is grounding somewhere it can and will still cause weird signals to reach the speakers.

BVC500

If inside in the dash on the passenger side, check the blower motor.My C280 whistled like that. Turn on and off the AC system and see if it whistles.

DRBC43AMG

Interesting tip as the radio would make a soft whine like in the old days your engine had bad spark suppresors. Basically the noise ceased if I turned off and on the radio. I'll pull out the unit and see if it the cause...

m00nsh0t

Is there any chance someone installed a supercharger without you knowing?

DRBC43AMG

I do look under the hood regularly but haven't found anything different....

DRBC43AMG

So drove around this afternoon to try and create this whining sound. Found something with the HEVAC control unit. When operating in AUTO mode, no noise is heard. As soon as I switch to air to the screen and to the foot-well, the whining sound starts. Guess I can take the stereo unit out of the picture.

I did a full diagnostic using my Carsoft program and everything is green OK.
I then did a diagnostic of the HEVAC unit (without the engine running but ignition on) and came up with three codes: 416, 417 and 419.
416 = Coolant circulation pump
417 = Left duo-valve
419 = A/C compressor electro-clutch

So what should I be looking at?

503C43 ////AMG

From what you are describing it sounds like the radio. Can you post a video? Pull the fuse on the radio, if it still makes the noise you can eliminate the radio as the source

cm60k

Did you figure out if noise comes from inside or outside..??

,,ZAYED,,

DRBC43AMG

I'm 99% sure it's from the inside or dash area

cm60k

Ahh good,

is the noise comes from behind the cluster..?, or from glove box side..??

,,ZAYED,,

DRBC43AMG

I have a feeling it is in the middle towards the glove box side. Could it be the duo-valve as it is in the engine compartment on that side and it does make an error code? See post #12 above

DRBC43AMG

I'll try doing a video tomorrow after disconnecting and pulling out the stereo unit.

Sulaco

Just unplug the amplifier in the trunk. No need to pull other stuff now. And if it is the amp, removing the head unit might not affect anything since the head unit only sends signal to the amp which then powers the speakers. If the problem is in the amp it could very well still be sending grounded signal to the speakers. This is tied to how some modern cars will pipe in different exhaust sounds into the interior: the grounding from the engine has subtle yet predictable change in voltage which the audio system can be easily modified to amplify and alter this signal however the owner prefers.

cm60k

^^Good input^^

,,ZAYED,,

DRBC43AMG

Thanks but I don't have an amp in the trunk. My unit is a more recent one which I changed as the original died on me some time back.

DRBC43AMG

I managed to make some videos this afternoon. The first one with the stereo unit installed normally but switched off, the second with the stereo unit removed. The whine/shriek is there with or without the radio, so that rules out a problem with that.

The more I drive and listen to this, the more I feel it's related with the ventilation flaps in the dashboard, but unfortunately I don't see what it could be....

DRBC43AMG

I described the problem and posted the two videos on the C36/C43 AMG Owners FB page this afternoon. Someone chimed in saying he had exactly the same problem. It's probably a leak in the vacuum actuators that move the flaps around in the climate control box. Need to get back in and under the dash in the passenger side and after removing the carpet apparently you get to see and have access to the flaps. Hopefully it's not the cabin recycle actuator as that apparently is a full dash out repair

Also when opening the heater duo-valve to check and clean the pistons and the inside (I had an HEVAC related error code when I checked yesterday), I managed to break the wires on one of the coils as I forgot to remove the plug before separating the coil bodies

Ordered a new one at the dealer arriving later this week, but this stupid "heavy hand" mistake will set me back by around $300 and not forgetting some fiddly work replacing as space around there with three hoses to disconnect and reconnect is a PITA. For my consolation when opening the unit, I saw that one of the pistons was rather worn and caked with crud. At least the new one will ensure that the heating works well.

AMG__Dom

Wow thats crazy, I just got my AC working after I did the swap and it makes the same sound, not as loud but I fear its just the start

DRBC43AMG

Could be.... Happy hunting