dtxmob

My car lets off a loud buzzin noise when i step on the gas and then let go from a roll. I hear it most at 20 mph when i press on the gas pedal then release it? The sound seems to be emitting from the rear of the car. Any help or input would be aprreciated. Thank you!

whoover

My guess would be blown muffler or other exhaust leak.

AP1ayer

could the buzzing be coming from the sunroof controls next to those little vents? try putting a little magnet there to see if the noise goes away. if it does, i have the same annoying problem and a mechanic says its the hvac motor? whatever that is, but they didnt have it in stock so i could not have it replaced. let me know if you resolve the issue.

whoover

That sounds like the aspirator motor. It's a tiny fan that sucks inside air over a temperature sensor for the climate control. It needed constant replacement in my W140, but fails much less frequently in the W220. When it goes bad it's a faint buzz, and can change during acceleration or deceleration. An exhaust leak sounds totally different, but is also buzzy -- coming from under the rear of the car.

AP1ayer

yea thats it! so aspirator motor = hvac? any idea on repair costs?

ebolick

glad im not alone, that is the same noise i am getting. what is the cost on that?

whoover

Yes, "aspirator" means it sucks air into the sensor that's part of the climate-control system. "HVAC" means "Heating, Ventilation and Air-Conditioning," in other words "climate control."

The only times I had it replaced it was on warranty, so I don't know cost. It shouldn't be very expensive I wouldn't think. The motor is cheap and so it all depends on labor, but I don't think it's a big deal to get to.