benzomonterey

in my coupe when parked and the key is out, I can hear a humming coming from the overhead console. I know there is a little vent or something up there oposite the sos button, but I thought it was for the climate control. This seems to run all the time. Any ideas?

o2bsurreal

I don't have teleaid, and I hear a hum after pulling the key out of the ignition too. I always assumed it was coming from the ventilation system - though I don't know how I came to that assumption.

o2bsurreal

P.S. I'd try to be more specific by going and checking it out right now, but our recent 10" of snow prevented me from driving it today.

mleskovar

I read somewhere that there is a pump that circulates coolant for a while after the engine is shut down.

benzomonterey

my particular sound is coming from the overhead console area. Even after several hours of sitting the car still makes the noise. Regardless of conditions ie; door open or shut, key in or out. I still want to believe it's part of the climate control but not sure.

MarkL

Benzo, I've noticed a slight hum in my C240 also when everything is shut off, but I've never really localized it. It's very slight. I'm wondering if your clue might be right. The little "vent" you see near the SOS button is the TeleAid microphone, I'm pretty sure. The only climate control sensor "inlet" I've noticed is on the climate control panel itself, you'll see a series of vertical slits in the center of the control. I've also thought it was some type of amplifier noise, but it's interesting that o2bsurreal hears it too w/o TeleAid. Wonder if it's the same sound. I'll try to listen more carefully to where it's coming from.

MLESKOVAR:
There is a pump that pumps the coolant back into the reservoir when you shut off the engine. You can usually hear it run for maybe 4-5 seconds. Had that on my Passat also. Also, it turns on if you activate the "rest" function on the climate control after you shut off the car. It's a louder noise than the one I think we're describing and it definitely stops after a few seconds.

benzomonterey

possibly I am incorrect but I thought the Tele aid microphone was the black circular one. I also have a small slotted vent like thing next to it. I will try to take a pic of it tonight.

MarkL

You're exactly right. I just went to run an errand, as soon as I got in my car, I realized I had forgotten about the other slots near the SOS button (not the black circle). I'll still try to localize the sound if I can. I kind of don't pay attention to it anymore.

young

is that the audiopilot microphone?

MB-BOB

Page 21... The round, black object between the overhead lights and the rear view mirror is the Teleaid microphone (doubles as the voice activated phone mic, if equipped.) That being known, the console colored "vent" opposite the "SOS" button must be the audiopilot microphone. (Notice the little holes in the round microphone face behind the console colored slats.) The placement makes sense for that purpose.

What are you guys doing to make your cars hum? My C320 doesn't hum (from the overhead console). Haven't you heard? BMW's hum! BMW's are the ultimate humming machines...

"Your manual is your best friend."

Amended 1/8/02 7:54 CST... Ooops, wait a minute... Uh, yes, it DOES hum, veeeeery slightly (you have to put your ear close to the console to hear it). Sounds electronic to me. My guess is a pre-amp for the various microphones. Or could it be a hum from the dash we hear at the console, directed up the windshield? I wouldn't think it's ventilation related. There are no ducts leading up the A-pillers to the console area, right? In any event, it's not going on my dealer to-do list... I'm not going to lose any sleep over this one. And to think my MB didn't hum like a BMW...

Curious? do non-teleaid equipped coupes still have the black teleaid microphone? You would still need it for the cell-phone package, yes?

Rick

wait....BMW's give hummers? Is that an option or a sales tactic?

benzomonterey

I am proud to say that I am a manual reader and that I searched high and low for a description of the slotted beige thing. Even in the coupe pics I couldn't find it in the descriptions of the overhead console.

I wouldn't mind a slight noise but mine sounds sort of like a fan on low speed if you are just sitting in the car with nothing running. Oh well. It also appears by my email that MBTech attempted to respond but his post didn't work. So I guess the mystery remains.


Happy Motoring

Richard

The temperature sensors for the airconditioning have little fans in them to circulate the air (otherwise the air wouldnt go into there to me measured) - if you put a 1cm by 1cm piece of paper over one of the temp-sensor vents it will be sucked onto the sensor and wont fall off - if the fan is working properly -.

I dont know where the sensor is on the C class, but it sounds like you (a) may have found it and (b) the fan in it may be noisy ...

MarkL

Richard, where did you find this info?

I tried the paper test as suggested, and sure enough, the overhead console "vent" (sensor) we're describing indeed holds the paper in place due to the fan. Same with the small vent on the climate control panel. I also discovered that with the ignition off, only the fan in the overhead console continues to run -- I guess constantly. The one on the climate control panel stops (paper fell). I wonder why the upper sensor fan runs all the time???

Benzo:
My fan noise is very faint and hardly noticeable. If yours sounds loud, there might be a problem. ( I do have a C240 but I would assume yours is the same).

MB-BOB

Whoa! Richard is right! I took a 1/2" square piece of typing paper out to the car over lunchtime. With the motor running the paper is sucked to the louvers and stays in place (it's not static electricity). Even after turning the motor off, the paper stays put for a minute or so, then falls. So, I think it really is a temperature sensor after all. That would explain the hum as a fan motor sound.

Mine seems to run at a slower speed when the motor is off (since the paper falls), so if the hum is pronounced on your cars, maybe the motor is (stuck) running full blast all the time. (My clim. cont. is set on auto at the moment, not EC mode)

Well, we're learning something new every day. Thanks, Richard. Now, I'm wondering where that audiopilot microphone is. Could it also work off the teleaid/cellphone mic?

MarkL, you beat me again, Bud! (5-minutes) LOL!

jnjrowland

Could the fan still be running due to the car being left in the "rest" mode that I read about. There is the feature to use residual heat to keep the car warm for some time after the engine is shut off. If this feature is set would that cause the little fan in the overhead to keep going as well?

John R.

MarkL

No, I don't think so. Read below. My car was off without the REST function running.

MB-BOB:
I also did this at lunch time. I knew if anyone checked it, it would be you! After I had parked the car for about 30 minutes at my house, I checked the overhead sensor fan again with the small piece of paper before I started up. The paper still stuck (anyway I could still hear the fan). I used a smaller piece of paper, so maybe yours was too heavy if the fan slowed down. But, has anyone noticed the sensor fan running at different speeds?

benzomonterey

what an interesting can of worms I opened. I feel better at least knowing my original climate control thoughts were correct. I seem to have hypersensitive ears when it comes to my cars so it may just be the normal noise I am hearing.

MarkL

Hey, BTW benzo, on the way back from lunch I heard the song with the line you've quoted on your signature line. I've probably heard it before, but since I've been seeing it on your posts, I was more aware. Do you know the song title? Interesting lyrics...

benzomonterey

the song is called Just Like Heaven by the cureThe Cure

MB-BOB

Circa '85-'87, right? Hmmm? Let's see what happens. Whenever I speak about the pre-Nirvana era, I get slammed by the young farts on this forum. Granted, the Cure isn't as vintage as the Guess Who, but my collection was current until, say, 1992...

benzomonterey

ding ding you win the prize1987

tommy

It's on Kiss Me, Kiss Me, Kiss Me. Awesome album (double album). F**ked up videos, of course. Second-best album after The Head on the Door.

Saw them on that tour. Lots of freaks there.

MB-BOB, good call (though I properly identified the song earlier in another thread, to pat my own back). :p

jelecroy

I heard that same humming noise from the overhead console on my C240, and finally convinced myself it's from the interior light dimming circuit. Just an opinion, but it sounds so much like a noisy little transformer to me.

I'd love to have someone tell me what it really is, though, and the confirming diagnostic

Jerry

MarkL

Jerry, the dimming of the light does make a noise like a transformer, but only while the dimming is happening. It took me a while to figure that one out too. But, if you've read the complete thread, I think we've concluded that there is a very small fan behind the temperature sensor slots near the SOS switch on the overhead console. A couple of us followed Richard's advice about the small piece of paper being held there by the fan's suction, and now that I've listened more closely, the slight sound is coming from that vent. I also tried the paper test after the car was off for several hours, and the suction was still present, as was the slight noise.

Look for Richard's post to this thread on the previous page and my follow-up and that of MB-BOB.