Strongirl

Hi, I just got a new 2014 E350 and when I turn off the engine and don't lock the doors there is a humming noise that lasts about 30 minutes coming from the engine. If I lock the doors the humming noise goes away in about a minute. Has anyone experienced this or does anyone know what it might be? Thank you in advance for any responses.

beshannon

Mine does the same thing, not sure it is a battery charging or something else.

Strongirl

Thank you beshannon. I am worried that it's going to run down the battery if it runs for 30 min.

thefisch

Had read on here that the 2014 LED headlights have a fan that cools them afterwards. Not sure what it could that it would matter if the doors are locked or not. Strange.

Strongirl

Thank you thefisch. I mentioned this weird humming to the saleslady and she checked with the service dept and they said that about the headlight fans too but it doesn't make sense to me - seems the headlights would need the same amount of cooling if I locked the doors like you said??

RSIKR

After you turn the engine off, the evaporator fan runs sometimes to remove moisture from the evaporator for the AC. If the moisture accumulates and gets to the in cabin air filter it can grow mold. Before this feature existed many contributors to the forum complained about the smell. Some drivers would turn off the AC a few minutes from their destination so the fan would atomize the excess moisture to combat this problem. I am not sure this is your problem. See if it sounds like a fan running.

What the relationship is to locking the car now or later is unknown to me. I always lock my car when walking away so I haven't noticed the difference.

I drove my 2010 4 years and I am into my 2014 a few months and haven't had any battery issues. It is included in the original warranty for replacement and isn't prorated to my knowledge. You do get MB road service.

Welcome to the forum, good luck, enjoy the car and read whatever konigstiger writes, it is the best information.

Do a search on this forum for "fan noise after car is off".

Strongirl

Thank you RSIKR, I live in the desert so the AC definitely gets a work out. You're right, it sounds like it could be a small fan. I'll check the forum for the "fan noise after the car is off" as you suggested. I lock my car too but not usually in my garage and that's where I hear it. Thank you very much for the welcome and for the tip about konigstiger too!

cleankutazn

Same exact thing happens to me too when I park in my garage without locking the doors. I also hear a loud thunk sound when I open the door after a few hours. I don't really worry about it. Mercedes always makes weird noises when the car is unlocked.

KEY08

I would concur with the LED headlamp fans as being the noise. Definately agree that MB produces cars that make more noise when turned off than when on. My airmatic farts a lot when turned off in the garage. I need to check on what I am feeding that bad boy.

Egonvdv

Is this a standard feature nowadays..?

velocity12

I would suggest that the car is making the same sound whether you lock or not and the garage is just echoing the sound.

Strongirl

Hi velocity12, No, it's definitely not an echo. When locked it stops in about a minute but, if unlocked it runs for a good 30 minutes which couldn't be an echo for that duration. I can hear the humming coming from hood near the lights and it is clearly something running. Thanks for the thought though.

Strongirl

Thank you all for your replies. I feel much more comfortable hearing that, whatever it is, it appears to be a common occurrence and not a defect specific to my car. I'm glad I joined this forum, you guys are great!

JohnAJohnson

I noticed the same on my car. I thought it might be the COMAND hard drive running.

Phil Midland

Just picked up my new indigo blue e350 yesterday. Sitting in the garage going over the manual, or just working on the car, I hear a high pitch whine while the acc is on (learning nav, audio features etc). When I leave the car, locked or no, the whine continues a while, then winds down, like a quiet siren. I have the adaptive led lights. The cooling fans might be the reason for this. I just hope it's not a warning sound about the battery condition.

Strongirl

Hi Phil,
I have the adaptive led lights too. I mentioned the noise to the person who sold me the car and she spoke to the service manager who said it was the cooling fan for the lights also. What doesn't make sense to me is why would they cool down and faster if I lock the car than when I don't? Locked noise stops within a minute or so and unlocked the noise continues for app. 30 minutes. Maybe I'll turn off the daytime running lights and see if the noise is there when the lights haven't even been on. Haven't tried that yet. I hope it isn't indicative of the battery too because I don't usually go very far when I drive - usually short trips which wouldn't recharge the battery well. It does appear that this is a common occurrence though (since a lot of people have reported it) and not something unique to my car or yours. If you hear anything more about it, please let me know.