Okay, so about a month back now I noticed this really high pitched squeaking noise whenever I let off the accelerator and slow down until about 20mph. It also stops when I switch to neutral. Now at first I thought it was transmission related, BUT I took it to my local mechanic that does mercedes, bmw, porsche and they say it is the vacuum system in the mercs. Something in there is leaking. He said climate control and locks moving up slowly etc is controlled by this system and something is leaking in the system. Then he tells me it will take about 10 labor hours just to FIND the problem because they have to remove dash and find the part that needs to be replaced!!!!! That's not even fixing it!! Do you guys think this is justified? Anyone ever had a similar problem? Any temporary or cheaper solutions!??! I do have the SLK Repair CD that shows me how to remove dash but it looks really hard and I don't think I can do it without somebody's help.

 

Does it make the sound more or less when you turn the air on or off? Or doesn't that affect the sound?

 

Clamp off vac line thru firewall and see if noise stops. If so then trace thru under dash to heater .

Bazzle

 

I did find out that if I turn on the Economy A/C the noise stops! However, when the AC is off or the EC button is not pressed, the noise is heard!

 

That is very strange, I would say leave the ec button on then! I have mine on 100% of the time anyway! Sorry I couldn't help more. I started to think in the begining that because it is fall that you possibly had a leaf stuck somewhere, lol.

 

ec button is disabling the clutch on the ac compressor, therefore your bearing is probably about to seize on the compressor. It probably leaked out its oil due to a leak