Mechanics

WHAT IS NOISE COMING FROM VENTS?

2002 Mercedes Benz ML500 • 137,000 miles

I hear a strange 'blowing'-air circulating with a different pitch then the ac from the vents. When I apply the breaks it stops. I was told possibly blend door? Possible or something else? The ac does blow cold. I haven't tried to switch it o the heat yet cause las Vegas is hot enough, lol. What can it be? How can I verify the problem? What would it take to fix it? Where is bad part located? Many thanks for the help
Avatar
Comptech61
September 11, 2012.



Does it make the noise with key on, engine off?

Possible vacuum leak

Roy

ASEMaster6371
Sep 11, 2012.
I am not sure. Didn't try it. Will check today. If it happens with engine off/key on is that the vacuum leak or the other way around?
Thanks for the response
Alan

Tiny
Comptech61
Sep 11, 2012.
Vacuum leak if the noise is gone

Roy

ASEMaster6371
Sep 11, 2012.
And if the noise is still there? Could it be blend door as was suggested or is there anther possibility?
Again thanks
Alan

Tiny
Comptech61
Sep 11, 2012.
Possible but lets start somewhere and not guess

ASEMaster6371
Sep 11, 2012.
The noise only happens with engine running. It sounds like it is only on drivers side

Tiny
Comptech61
Sep 12, 2012.
And coming from under the dash, not from the vents

Tiny
Comptech61
Sep 12, 2012.
You have a vacuum leak somewhere and need to locate the source.

Noise stopping when applying brakes could mean a fault with the brake booster or related components.

KHLow2008
Sep 12, 2012.
I have driven the truck and the brakes seem fine. No problems stopping nor spongy. Could it still be the break boster or what other possibilities can it be? Sounds like it could be expensive to fix? Or can I be lucky and have a bad or unconnected vacuum line?

Tiny
Comptech61
Sep 13, 2012.
It is possible to be a vacuum leakage somewhere but without further probing, you can't be sure.

If it is a brake vacuum, it won't become spongy, instead more pedal effort is needed and repeated pumping of brake pedal would result in a stiffer pedal.

When you try to start vhicle after starting, before you tirn ignition on, test if the brake pedal is soft or stiff.

KHLow2008
Sep 13, 2012.