The "hours after" throws me a bit, BUT the whine/cooling fan noise is probably the after engine shut down turbo cooling pump. Obviously turbos run hot and the bearings in the units reside in a rather brutal environment and that becomes worse when the engine is turned off and bearings sit in oil that is cooking from the heat (term is called coking)…basically a turbo creates extremely high temperatures that will cause the lubrication in the turbo bearing housing to disintegrate and causes coking. A way to avoid this situation is for the cooling oil to continue to circulate thru the turbo thus the 'whine/fan running' sound of the turbo oil pump in action.

 

One thing I did run into is the Can Bus activating. I was working with my Valentine One detector using their new SAVVY module for power that plugs into the OBDII port.
Something with this was being sensed by the Can Bus Network and activating things every 15 minutes for maybe 30 seconds as the Network was detecting and monitoring I am guessing a residual current somewhere, so basically the Alarm system was monitoring and slowly draining power. This was a known issue from Valentine One and they thought it did not occur on the GLA without Keyless, but I proved even on the Non-Keyless GLA it was still an issue. I have not heard if they have the Firmware resolution for Savvy yet.
If you have something external connected, it could be causing this as well. Would not see the battery drain unless you leave the car sit for days on end.
Was real easy to hear if listening to the ECU area under the hood, you could hear it kick on for aforementioned 30 seconds, then kick back off.

 

Thank you SSBGLA45 and johfinz for responding. I will try to eliminate or determine if these are the causes.

SSBGLA45 - This answer seems a real possibility. I notice my car is making no noise at my office after being parked 4 hours right now. But frequently I drive home 17 miles. Go in eat dinner, read the paper and maybe watch the news. I go back to the garage/barn with no electricity and it is making the noises. I need to verify but I think I can also go out on a Saturday morning after the car has been sitting all night and hear the noises in the morning at times. I will start recording the times and see if I can determine a pattern. But I can tell you after driving the car for 10 months pretty much the same everyday and I have no sense of a pattern and am sometimes shocked it is making noises and worry about battery life.

Johfinz - I did have a mp3 music player plugged in to the usb port continuously. I will plug it back in and see if that could have been the cause.

I think I will check if it is related to when I have my phone on me and wonder if it is the bluetooth activating in the car when I am near it. That's not it. Just checked.

 

Last night I went home and parked my car outside as I had an evening meeting. An hour later I went to the car and it was making the noise. I went to pop the hood and when I opened the driver door to access the hood latch it stopped making the noise. I pulled the hood lever, shut the drivers door and opened the hood. About 30 seconds after I opened the hood it started the noise again for about 5-10 seconds then quit.

Thoughts?

 

Tim,
Do you have the Keyless system or the Key solution?
is the Car Locked or Unlocked when this occurs, makes we wonder if it's recognizing the key being nearby, my Buick Regal GS which was keyless would recognize the key being in proximity and things start to come to life. I think my GLA seems to do this as well up to a certain point. If I leave it for a couple days, I have to hit a button on the Key fob to wake it back up. I had my hood open the other night and I noticed things were coming on from that as well, so I am sure it is recognizing the hood open contact and kicking the Can bus awake to monitor, but my car was unlocked sitting in the garage. Haven't tried this with Locked condition.

Just more thoughts to try and look at.

 

I think I have noticed it with the key fob in the house still I will double check that. I did not have the doors locked in the above mentioned sequence so I did not use the fob for anything. But it was in my pocket. I don't have the key less entry or whatever the key solution is that I know of.

The leaving it for a couple of days and it sleeping kind of sounds familiar to mine. I will keep testing.

 

After two hours in the garage, the motor area had a low "hum" eminating...Just after opening the driver door the hum stopped.

Kinda sounded like a very quiet fan,a very quiet PC muffin fan.

 

My CLA 250 did this. It's normal for these cars. You should hear what my GLA45 sounds like when I park it?

 

Most newer cars have a constant low level ecu activity 24/7. There are a lot if checks it conducts while in the off state. Most of the time it is related to the anti-theft mechanism built into the vehicle. Just checks and balances. The GLA is not too insulated as far as noise is concerned, therefore it's more noticeable than other cars.

 

I also get this noise, happens most days about half an hour after it gets parked in the garage.
Been to the dealer twice, but of course it didn't do it and they had no idea what it was. I think the service department thought I was making it up.
In the end mentioned it to the sales rep. that we purchased from and he followed up with Merc. This is the response from them.


The noise that you are experiencing is the "Residual Heat Pump" that is designed to circulate water to cool the engine below certain parameters, this is done via a pump with a separate module to run it so it doesn't run your battery flat.
This can happen well after the vehicle has been switched off and can run anything up to 1.5 hours.


Pity the service department didn't know, would have saved me a lot of time and worry.


Trevor

 

Welcome to the forum tasmerc! This is excellent information. I've heard this sound myself and wondered what it was. Appreciate your contribution to our community body of knowledge.

 

This forum has helped me out a bit, and when I saw this post and the theories, whilst I new the correct answer it was only fair that I join up and put a bit back in.


Trevor

 

That's what makes this a great forum! We look forward to your continued observations, there's no shortage of questions that pop up. We're all learning together.

 

Sorry to dredge up an old topic. I asked my dealership about the noise I was hearing, which is the same as described in this in this topic. I mentioned that I googled and found the answer provided in this topic and asked if they were in agreement.

The following is the shop foreman's reply, which seems reasonable since I have been using my AC recently. I will check out the 1 hour and the 30 minute event timing mentioned when I get a chance.

Good morning,

It sounds like what Mr. xxxxx is hearing is the blower motor for the climate control. Under certain conditions the blower motor will be activated 1 hour after the vehicle is shut down and will operate for up to 30 minutes. This is to facilitate drying of the A/C evaporator in order to minimize the risk of moisture related odor. The information from the forum is incorrect. The activation is initialized by the climate control control unit. The function will not occur if the battery charge level is low so as not to compromise the battery.

Regards,

xxxx xxxxxx
Shop Foreman, Mercedes-Benz of xxxxxxxxxx
AMG Performance Center
2015 Best of the Best Award Winning Dealership
Master Certified
Certified Diagnostic Technician

 

I've heard the small circulation pump, suppose to provide cooling for the turbos and bearings, protects from residual heat. Didn't know about the blower Como g on to dry a/c coils but makes sense. I'm going to leave windows down and see if when I heard the blowing I can just reach in and feel if air is coming from vents a a test. If this feature is for real it doesn't work to prevent mildew because I've had a mildew smell that needed deodorizing.

 

Hi

I have a C250 AMG and I've noticed a noise Aswell but still hearing it after 3+hours please see video attached

https://youtu.be/N7bVKdqAfN4

 

So, what you guys are actually hearing is a vacuum pump in the EVAP system. After 5 hours, if all the requirements are met, like the temp sensor reading cool enough for long enough. This vacuum pump comes on to test the integrity of the evap system. If things aren't right, then there are specific codes it sets off. The reasoning behind this, is because the the two valves in a modern EVAP system, activate hundreds of times a minute and are prone to failure after a few years. Only now, that system is depended upon for a smooth running engine. When the system is not attended to in modern vehicles, it leads to carbon buildup and expensive engine damage.

Oh, and I guess it might be some sort of heat pump, like someone else listed, but I have yet to encounter this part yet. The electric water pump in Mercedes vehicles, as far as I know, is used to pressurize the cooling system from the reservoir bottle used these days. It's one of the noises you hear when first inserting your key to start.

 

Welcome to the GLA forum Red. That's one of the best theories or explanations we've heard. Are you a GLA driver? If so, tell us more about your GLA.

 

It's threads like this that make me love this forum and also really appreciate how high tech my GLA is.

 

Yes sir Tim ... The MB keyless system is scanning for your smartKey. In the earlier German car system there were a lot of criticism that they were not "sensitive" enough, so I have noticed that in my GLA (production date of 12/16) it is super sensitive. In my '98 BMW e46 (3.28xi) you had to literally wave the fob key by the door with left hand in order to activate the unlock feature with right had! Also the auto/stop feature will require the brake vacuum to be boosted, I believe this is done through electric vacuum pump, there is a master cylinder and I there is hydraulic fluid but did not see any fluid reservoir. I believe that vacuum booster is charged up whenever the smartKey is detected. This will present another interesting dilemma when one is changing disc pads - I read on Prius blogs that the caliper piston would shot out whenever the booster vac was self activated.

I also noticed that after driving a distance, (w/A/C on auto) park the car, lock it and come back shortly afterwards unlock it and seat in the driver's side there is a very gentle cool breeze coming out of the two outer dash vents. And there was a very non-audible hum. When I exit the car again, lock it, and come back the hum was gone. I did not set anything on the HVAC nor turned on any accessories either.

I have attached a battery tender with amp meter, and definitely noticed an increase current being charged initially and then stepped down to trickle. I did after driving for a while and parked. This is concern to me because I often park my cars for extended period of time, so it appears that the newer cars in general are so dependent on electric consuming devices that it will discharge itself by just leaving it parking. I do remember reading about this in the Owner's manual.

 

PS: There is always a minimum amp reserve capacity for an engine start, so there is no worry about completely draining your battery by self activating system devices. I also agree on other comments about ECU being active all the time. When the engine is OFF it does not mean that your car is shut down. Now that the GLA got remote start by iOS/Android, the next interesting dilemma is hacking !!! They have already successfully "jail broken" the GLA AMG45 in Taiwan.

 

So by using the hold feature at the lights most of the times is gonna hurt the brakes?
i love the feature, but if its gonna mess up disk i am not gonna do it.
thanks,
C

 

These threads (this one and the e-brake thread) just show how unnecessarily complex all cars (not only the GLA) are today. All these gizmos will fail at some point soon in these cars' lives. Failure frequency also depends on use pattern, as discussed by many.

Many of these gizmos are in place to mitigate the incompetence of many drivers and ins response to stupid lawsuits. We are all paying for that.

 

There is a small circulator pump (part #0-392-023-206 ) right where the front bumper underbody shroud terminates. There is a hose connected to it, you can pinch this hose and feel the coolant running. Don't think this is the main pump, this is to aid in cooling during Auto/Stop, I think it will stop once the coolant reaches a set cooled off temperature.

 

both of our MBZ's make this noise. if you open and close the door it stops the sound - not sure why it does not start up again. i have a high power PoE switch in the garage so we do not hear the two cars too much.

 

The electric parking brake performs a function test at regular intervals while the engine is switched off. The sounds that can be heard while this is occurring are normal.

 

I have noticed my car makes various noises hours after it is shut off. Sometimes it sounds like a tiny cooling fan somewhere in the firewall area. Sometimes it sounds more like a whining noise. I don't touch the car, have the key on me, or even have any embrace options.
The car has a base radio.

I had this same issue, where I'd hear that "fan blowing" sound long after the car was parked. I found locking the doors caused the noise to stop.