kaustabsaha

I drive a 2013 ML350 4matic (w166), that I purchased certified-pre-owned on Aug2015. Since then I have been struggling with a moldy or vinegar like foul smell coming out from the AC vents during summer, when the AC has been turned off and only blower is on (re-circulation turned off). I have searched the internet pretty hard on this issue and understand that mold/mildew can develop on the evaporator in humid weather conditions, and the best suggestion was to turn off AC and have the blower run for about a mile before reaching the destination and turning the car off. I have been doing that as a practice but the odour problem still showed up this year. This same problem also showed up on my earlier brand-new 2014 C300 in it's 2nd year of ownership. The service department at the mercedes dealership said that sometimes mold can accumulate in the evaporator, and they deodorized the AC system using BG Frigi-fresh. This took care of the smell temporarily for about 2 months, and then it started coming back last year, but by then it was winter and the smell went away. This year (2017) the smell is back again and stronger than before. I have tried to clean the evaporator by spraying Lysol Disinfectant, 1Z Einszett Klima cleaner, Interdynamics AC Duct Cleaner into the system via the blower motor (by removing cabin air filters) and that took care of the smell for about 3 weeks, and now the smell is back again. There is no smell when the AC is on (both recirc ON and OFF). However, after I turn the AC off and keep the blower running, that's when the smell starts to come out of the vents after about 7 mins. Is there anyone else facing same issue? Any idea on what might be actually wrong and how to get this fixed?

DanD.

I personally don't have this problem, please see this, if you didn't see it before.
https://mbworld.org/forums/m-class-w166/453553-smell-when-starting-ac.html

dieseldoc

Had this with my c class. Dealer clean out AC system and installed new filter. It has been 16 months. No return of smell.

NickW

I had this issue in my 13 ML. Took it to the dealer and paid 150ish for an A/C cleaning and filter change. Smell went away for 2 weeks and slowly started coming back. Took it back in and they called Mercedes USA and did it again along with a few other things that I can't remember. Been about a month and no smell at all.

peter2772000

All later-model vehicles have this issue. I have it on my 2007 Toyota FJ Cruiser & 2014 GC SRT. On the FJ, using a OEM foam cleaner made the issue go away for a while.


I have been told that this issue is caused by the choice of metals used in the fabrication of the evaporator which, when combined together, create a funky stink

kaustabsaha

MB does not officially warrant this issue. However, I somewhat agree in the material used in fabrication of evaporator. While searching through internet, I found that there are current 2 class action lawsuits open and in-progress against MB USA for this issue. One if the district court of California and the other in Georgia. More info at https://www.law360.com/articles/9234...dy-hvac-system

kaustabsaha

I took it to the MB dealer and they were a bit lost and hesitant to answer when I asked them for the root cause of the smell. The SA answered that he does not know and has no idea what is causing the smell. They "deodorized" the AC system, for free, and asked me to pay for replacement cabin air filters (parts only) and took care of the labor. It has been a week after the service and the smell has not come back yet. Their behavior makes me think that they are aware of a design defect but cannot openly accept it, and deodorizing the AC system as a band-aid fix is what MB has advised them to do in these cases.

kaustabsaha

Anybody know anything about the class action lawsuit around this issue?
Details: https://www.law360.com/articles/9234...dy-hvac-system

ItalianJoe1

There is an LI addressing this on the 166 chassis, to seal some body openings, disinfect the evap and install newer cabin filters. If the veh is in warranty they should do it no problem.

kaustabsaha

Thanks. What is a LI? The SA at the dealer did mention about this, and said that it is a very involved process and they did it in one of these vehicles a while back. He said if the smell comes back in my car then he will be talking to the tech to see if the same sealing procedure needs to be performed. My CPO warranty just expired in June '17, and I am currently on the Extended Warranty till June '19.

ItalianJoe1

LI is like a service bulletin. Basically, a tested repair method to address known problems, to help techs fix the cars faster and fix them the first time.

We've done a couple of the 166s for the vinegar odor, usually just an evap cleaning with the actual disinfectant and new filters is sufficient, the body openings are plugged in the newer cars from the factory but seeing that yours is a couple years old they may not be.

f4i 954

any chance to get more info on the body openings??
location?
do you know the LI number?

ItalianJoe1

I will look it up tomorrow, and try to attach it here for review. It's a long LI. There are actually 2, one simple one that says to start with the newest updated filters and an EVAP cleaner, then if that doesn't work, seal the body openings and re-do the cleaning. On the newer build cars, the body openings are sealed from factory though and they still have a smell.

f4i 954

I have cleaned mine 2 times and its almost gone but there is still smell, i am just curious to know what effect the body openings have on this

ItalianJoe1

This is the second step repair, with the two illustrated sealing documents attached.

LI00.00-P-066036_Ver_1.pdf

LI00.00-P-066036_2.pdf

LI00.00-P-066036_3.pdf

This is the LI that you are supposed to perform first, before doing the one above.

LI00.00-P-066047_Ver_2.pdf

FWIW, the body sealing I don't think makes much of a difference, as the newer cars already have it done from production and we still get the odors in the car.

Every benz model does it, it's worse when the cabin filter is old as it traps the smell and releases a burst of it when the blower is started the first time.

There is also a software update for the a/c control unit that changes the wait time to start the blow-dry function to dry the evaporator after shutdown, from 1 hour to 3 minutes. This I think does more than anything, as it doesn't stay wet and doesn't get moldy to get the smell.

f4i 954

thanks for the info, i will update the climate control and change the settings, way to much work to seal the body.
i am guessing mine will need it, when you say newer cars don't need it, how new are we talking about?? i have a 2012 w166.

ItalianJoe1

I've only personally had to do it on 2015-16 cars, but the bulletin is new.

I don't think the body sealing does much of anything really.

TA Canada

Hi All,
Great info!
I have a 2015 ML 350 BT (Cdn build) with 44,000km (30K miles) on it and am having this musky smell at start-up for about 5 minutes then it "goes away" until the next stop and start.
Does anyone know for certain if this LI or service bulletin applies to Cdn vehicles as well as US ones?
Could I take these LI's to the MB dealer and have them perform the work under warranty conditions as well?
Thanls for any help!

f4i 954

As of 4 weeks ago updating the climate control on a 2012 did not give me the same options to change the coding as stated on the TSB, in Canada there is the one to clean the evaporator only and i don't think its covered under warranty

Wfrager

I too had the moldy smell, wife really hated it. I changed the filters and sprayed Kool-It evap cleaner. No more smell!

PositiveRate

ItalianJoe1

It should apply to any 166 chassis, unless the variant of AAC changed at some point.

PTCBenz

My dealer is saying they don't see this update for my '13 GL550. Is there anything I can tell them so they know how to look it up?

EDIT: I found it. It's within LI00.00-P-066047_Ver_2.
4. Update the latest software for the air conditioning control unit.
5. After the update go into workshop coding and set the following codings:
a) coding #000 (Regulation of evaporator temperature) to: "Fixed value 2°C"
b) coding #005 (Drying of the evaporator after the ignition is switched off (Waiting time: '1h')) to "NO"
c) coding #006 (Drying of the evaporator after the ignition is switched off (Waiting time: '3min')) to "YES"

ItalianJoe1

Yep, they have to read and follow all the steps.

FireRx Captain

That is exactly what I do on every cabin filter replacement interval.