For about 6 months, my lumbar support on the driver's seat will randomly lose its air, thus the controller thinks there is a leak, and therefore turns off the compressor until car is completely turned off.
Things I've done and observed:
First, I researched this forum and found a little discussion which was helpful. Next, I swapped the driver's and passenger's control modules which didn't change anything.
If i give a low lumbar number setting, such 4 or less, the pressure will lose itself more often than if I have a lumbar setting of six or more. This makes me think it is a valve issue with a higher pressure holding valve closed??

Where is the air comporessor for the seat? I have the back off, but can't find it.
I see three lumbar rectangular/flat devices on the right hand side of the lumbar area, each with wires going to them - are these the only valves for lumbar?
Is there a valve somewhere else between compressor and lumbar rectangular devices?

On mbonline, I see there is a part number 221-800-01-78 called valve for $140.25?

Thoughts?

The VIN is
WDDNG71X79A283211

Check pneumatic lines for leaks and kinks.

If found to be bladder replacement part is 2219102275 (505 in diagram) pictured here: https://www.ecstuning.com/b-genuine-...er/2219102275/ 2218000178 (530) is not applicable to your VIN see attachments.

Possible DIY bladder repair: https://mbworld.org/forums/s-class-w...-puncture.html

Pump: http://workshop-manuals.com/mercedes...on/page_19152/ see attachment for panel removal.

You guys are great! What a resource!

My car has about 70,000 miles and everything looked tip top behind the seat cover. No kinks, no loose connections.

So there's only one pump, and it's in the trunk.

Does the part number below, the dynamic seat air bladder assembly,
2219102275
have valves which is what is electrically connected on the assembly?
Are these the ONLY valves controlling lumbar, therefore I should order a new bladder assembly? When lumbar fails, the other bladders can still be adjusted.

Many thanks!

Most common malfunction, bladder failure. As shown in ECS link above, seat adapter incorporates valves, etc. Definitive diagnose before replacing part(s), have someone check for fault codes using MB DAS.

Out of curiosity, how hard is it to replace the bladders in the dynamic seats?

I "exercise" them every once in a while but figure they'll blow out eventually so I use them with care.

freinds,
the fault code is 9210.
failure of backrest module carrier.

thoughts?

Bladders are inflated/regulated by a control module and air distribution center called a module carrier (adapter) = part # 2219102275 referenced in above post. Read bulletin here: http://workshop-manuals.com/mercedes...oesnt_inflate/ + next pages.

Thank you! So the manual is suggesting replacing the module carrier. Is there a place to order the module carrier that supports this forum?

next, can I purchase a DTC code reader that is very thorough for my car?

It has been almost a week since I installed the new dynamic lumbar air bladder system and all is working properly!
Many thanks again to all!
Im very impressed with the Mercedes quality of workmanship. Every part in the seat has a p/n label and everything is designed to be taken apart or removed. Very nice!

It did take a few hours work, but I was exploring carefully and gently as I realized what had to be removed to get to the air bladder system.

sweet that it worked out for you.
im trying to do the same.... my left bladder making that hissing air sound when compressor pumps air to it...

not a complicated job ?

I thought was easy enough because everything is designed to come Apart.
Seat out is easiest so you can work all around it.
im in Dallas, you?
my old unit has good bags if you want to purchase my old unit. My guess is one of the lumbar controllers failed, but my bladders are good.
pm me if interested