Mastcell

I have a October 2013 built, 2014 spec ML350BT with the 2-zone Thermatic climate control system. There is option to select one of 7 steps for the fan speed in manual mode. However, when set to 'Auto' mode, I noticed that the fan speed never drop below ~4, even after allowing time for the stabilisation of the aircon vs ambient temperature. This is bugging me because you would think the fan speed should vary according to load, i.e., from 1-7, and not from 4 up, which is currently the case - it creates a lot of unnecessary wind noise.

Can someone check their unit and tell me if what I got is normal or faulty? Can the fan speed/temperature be adjusted at a service centre?

Strafzettel

The fan noise bothers me too. My C-class did it and my ML does it too. I always push Auto and then I lower the fan speed to 3 or even 2, that works just fine.

GregGebhardt

I manually lower the speed. When the vehicle is hot, my ML uses a the highest fan speed in an attempt to cool it down. I lower the speed to kill some of the noise when I need to make or answer a phone call. After a few minutes you can hit auto.

Mastcell

That is too comical for three pointed star vehicles!!

As I have said, you would expect the full range of fan speed to vary with the prevailing thermal load.

I mean, what is the point of calling it an 'Automatic' Climate Control if one has to manually over-ride it all the time? My japanese car at one third the price of a ML350 can do this, and I never have to manually over-ride it. I don't know to whether to laugh or cry about it...

GregGebhardt

It is only funny if you think so.

I do not have to overide mine, I only choose to do so sometimes. The system works quite well and after reaching the proper temp, I can not longer hear the fan, I could not ask for more. I simply sometimes choose to lower the fan speed due to noise when I want!

MDMercedesGuy

That doesn't seem right. My C will use the full range.

How low are you setting the temp when this happens?

Samaral

I notice that on the ML it takes way longer to reach a comfortable temp that took on the C, but again the ML it is way bigger then the C. Once the temp is reached, the fan it is really quiet.

MDMercedesGuy

That's why I was wondering about temp. At an outside ambient temp of about 90*F, my A/C will push my interior to about 66*F and be able to maintain it with low fan speed. If I set the temp any lower, it won't drop the blower down. I would imagine the extra volume of the ML may preclude it being able to drop too low.

I have a medium shaded exterior color with an ash interior, so that may have something to do with it - too. My A/C would have to work a lot harder if my car were black on black, for example.

Mastcell

My usual setting is 22 Celsius (72F) and it is almost always set in the single zone. 22C/72F is roughly in the middle of the temperature range. The current external temperature is around 18C/64F.

Even if it is too hot or too cold to begin with, one would expect the interior temperature to be equilibrated after running Thermatic in Auto for 30mins. My issue is, there remains a noticeable 'whoosh', which goes away if the fan speed is manually dropped to '3' or '2'. Therefore, the Auto fan speed must be above '3' in Auto mode.

I tried various combinations of dial temperature, single/dual temperature zones, air-con on or off, day time or night time, but the fan speed is always higher than '3'. Is this normal for Auto mode?

Nanook

My Escalade used to "mute" the fan when receiving a phone call

fabbrisd1

Well mate - YES it can be normal in high humidity areas like Perth - since it needs to run "high" to try to bring down your 70%+ humidity in the cabin and prevent window fogging..

Mastcell

Fabbrisd1, depending on which figure you quote, I can tell you that Perth is not humid like Brisbane (I lived there for 3 years). Regardless of whether it is humid or not, I am asking why the maintenance speed is stuck at level 4, and not the initial fan speed to clear the humid interior air. Take for example, a friend has a 3 tonnes Toyota Landcruiser Sahara, $130k with all the options. The aircon ventilates the massive interior cabin with barely a whisper. He just laugh at my problem. Ok, I get the rough message from the first two replies, indirectly that high fan speed is the MB way.

fabbrisd1

Well... for some folks 70%+ humidity is home... you might try using the recirculation button as addressed in the manual so that the "mist" feature can dehumidiy the air in the cabin without bringing in more humidity from the outside air... should help... but down under most need something to gab and gab about

Samaral

I am in Florida now and it is hot an very humid. It takes 15 minutes for the car to cool down and the fan slow down a bit. I am using 18C auto settings, no dual temp and outside air off.
I believe my car takes a little longer due to the fact that Diesel uses average lower rev on the engine comparing to Gas models.

Mastcell

Dear Samaral,
Would you please do me a favour?
(1) Put your Thermatic into Auto mode with or without Air-Con. Let it run for 15mins or longer.
(2) Hit the 'Small Fan' button, and would you please report back how many vertical bars do you see? That is all I want to know if mine is normal or not. (I get 3; but if I hit the 'Big Fan' button, I get 5. i.e., Auto mode defaults to 4.)
(3) You can return your Thermatic back to any mode you want thereafter.

Thanks so much.

I attached photos of what I get below:

Samaral

Will do it.

Samaral

I did it. After 15 minutes in auto, ac on, settings to 18C and outside temp at 25C(I am back to Toronto), I hit the small fan button and came up with 5 bars, lowering a bit the fan speed. After I returned to auto, gave another 15 minutes and hit the button again. This time came to 3 bars and no change of speed on the fan, that was already in low speed.

Cybercap

Hi Mastcell

Same problem here on a french 2014 GLK. The auto setting (ac on or off) defaults to 4 out of 7 vertical bars. If you shut the music down, the blowing is very audible and annoying. Pressing minus power goes to 3 and is far better and should be this way.
I'd like to find a solution to have auto on 3 or 2. I don't want to mess with it manually.
I owned a VW Tiguan and an Audi Q3 and the ac system would lower the faw speed as low as possible (even to 1) once the temp is reached.
I asked mercedes tech but they did not know...

Kaasmann

I have the same problem on my '13 ML BT, and I always have to override it, then have to turn off the AC in any temperature less than 20 degrees outside, including -30 degrees Celsius.

Cybercap

yes I thought we could fix it by software but the MB techs don't seem to have the answer.
There is also a hidden menu on the gps with info stuff but apparently no way to lower that auto value

Mastcell

Hi Cybercap,

Thanks for your comment. I took out a loan C250 BT (the latest model) last January when I sent my ML350BT for service. In my limited time in the C250BT, it also default to 4 bars when switching out of the full AUTO mode. However, the 4bar fan speed is not as noisy as in the ML350BT subjectively, so I am suspicious the Auto programming is the same across the models but other factors are changed, e.g. more/larger air vents.

These days, I just learnt to live with it. Here are a few helpful tips:

1. Turn up the radio.
2. Whilst absolute silence is golden at traffic light if you got Stop-start, just accept the air noise and don't get too cut up by it.
3. The fan speed setting is mostly right for the ambient temperature. Any lower and the cabin will either be too hot or too cold.
4. If you really need the A/C, just turn it on, the refrigerated air will allow the fan speed to drop sooner. If you enter a hot car and leave the auto on but A/C off, the thing will blast at 6 or 7 bars endlessly.
5. If you got a sunroof, open it a little to let out the hot air initially. The service technician told me one of the temperature sensor is located in the receptacle above the rear view mirror (for MLs) and the sooner the hot air in that region is evacuated, the sooner the fan speed will drop.
6. Just accept the auto climate control in Mercedes is primitive, you will have adjust something sometimes - the A/C button or the fan speed or the temperature .

* These are my personal tips to cope with the problem.

caf

Since one of the first things I do after getting in my car is making a phone call, I'm often turning down the fan, which is excessively noisy.

My Porsche Cayenne has a setting in the menu for "soft, regular, or extra" fan speeds. I set it on soft and I don't get the crazy noisy fan thing. Mercedes take note!

Vincecam

I have the exact same complaint with my '13 ML350BT. Also, infrequently the cabin gets cold with cold air blowing and the temperature control has no effect. The behavior goes away with the next restart. This has only happend 3 or 4 times.

Cybercap

Mastcell,

Just to let you know that I have posted a lot of screenshots of the engineering menu (access with hang-up + # + 1) on that thread :

https://mbworld.org/forums/glk-class...ring-menu.html

I'm still confident I might find out how to lower the AUTO-4-bars fan setting of the air con system...