sbsyncro

As a starting point to repairing my Airmatic system, I am trying to get the compressor working, after which time I will then be able to diagnose the source of my air leaks.

Compressor does not run when doors are locked/unlocked, but I can hear clicks and air leaking from valves (indicating to me that solenoids are opening expecting air flow, but since there is none, the air is escaping and flowing back toward the compressor).

I pulled the power connector from the compressor and put a voltmeter across the brown and red leads. When I hear the solenoids activating and the air leaking, there is no voltage across these leads at all.

1) Should there be voltage across these leads when I hear the solenoids clicking and air escaping? (I assume so).
2) If so, where are the fuses and relays related to the compressor? My research so far has made me very confused - I see references to fuses and relays under the hood, behind the driver's left knee, and under the passenger floor board.

3) Is there a safe way to "bench test" the compressor?

This is a January 2006 W211 (E500) with Airmatic but w/o 4Matic.

Any troubleshooting tips would be greatly appreciated.

Plutoe

You can continue on with a FUYAA approach or find someone with MB diagnostics DAS Xentry or when all else fails subscribe to MB WIS and put your VIN in and look for the wiring diagrams that include all the component locations to assist in your weeks long project.

sbsyncro

Ok... So basically what you're saying is that this system is so complex that it is beyond the realm of normal human comprehension without weeks/years of training or thousands of dollars in specialized equipment? (I'm not being sarcastic - that is a genuine question)

No wonder this thing is only worth $4,000 with only 58,000 miles on it. I've owned it since it was a year old and always took it to the dealer or a certified shop for service, but I'm not going to take it to a dealer and spend $5,000 to fix it at this point. I was hoping to breath a few more years of life into it, since I dearly love this car.

So it sounds like I should just call a tow truck and have it towed to the junk yard?

Oldgold

Here's something I found whilst reading up on this stuff for my E500. I imagine it's pretty much the same.. It's a long read but about halfway down it tells you how to test the compressor.

https://w220.ee/Airmatic

kajtek1

Nice find Oldgold.
What I see to answer OP question is
"The AIRmatic with ADS control module is "woken up" using the remote control, door contact switches or trunk illumination switch in order to check the current vehicle level for critical conditions (level too low) and if necessary to raise the vehicle or lower it when unloading. If the vehicle level is lowered by more than 30 mm, it is raised to the normal level by the reservoir (only with a reservoir pressure > 11 bar). At a vehicle level of < -65 mm and even at a reservoir pressure of <11 bar it is raised out of the "critical range" by the compressor to -63 mm (condition: battery voltage > 12.4 V)."
Air systems was 1 of my majors, so it is clear for me (even considering there is lot of "ifs" in the logic).
But can average driver comprehend the explanation?
Definitely not Plutoe.

konigstiger

Asked and answered: https://mbworld.org/forums/e-class-w...ml#post7845591

sbsyncro

Actually this particular question (at least the way I intended it) is uniquely and narrowly addressed at testing the compressor itself. My other thread which you've linked started (and has continued) as a more general "why did one side of my car drop".

I saw this as a specific (and more narrow) topic and thus posted it as a separate thread; perhaps I should have kept them together - sometimes a delicate balance on technical forums, I know.

At any rate, if there is something in that other thread that narrowly addresses the question I've asked here, I missed it (perhaps due to my newness to the Airmatic system).

I just ordered an iCarsoft MB II scanner that arrives tomorrow. Hopefully that will provide me with some better information; it sounds like thats the only way to figure out what the car is doing and why the compressor isn't running.

FWIW, based on my research I don't think the W211 has a reservoir for the air compressor; but then again it seems with these cars, there are too many variants to ever be sure about any particular configuration!

sbsyncro

Thanks. That information was actually posted to my other thread located here 10

My problem is that when I do any of those things, I can hear solenoids activating, but the compressor does not run. I pulled out the belly shield, removed driver's side wheel and fender liner, and pulled the main power plug from the compressor. I then tested voltage across the red and brown wires while activating the system using the methods you describe (and posted in the other thread by konigstiger) . However, I don't get any voltage readings under any of the conditions described.

Now I'm wondering if there is another way to safely test the compressor - such as applying 12v directly across these leads... I don't want to blow up any expensive control modules anywhere in my ignorance, making my PITA problem an even more expensive and bigger PITA.

Thanks

kajtek1

Let me try to "translate it" (English is my 3rd language if that matter)
Compressor in woken up mode comes only when the tank pressure is depleted, the car drops below critical range and battery voltage is above12.4V
You have 3 factors to check before judging compressor bad.

sbsyncro

Thank you. Does the W211 have a tank/reservoir? I didn't think it did. (there are only 5 connections on the valve manifold that I see) . The car is definitely dropped below critical level (although the red light is no longer showing on dash).

Actuating the "Raise Vehicle" button with the engine running also does not activate the pump nor cause voltage across the red & brown wires leading to the pump. I have verified that the 40A fuse under the passenger floorboard is intact and Fuse #37 in the driver's side panel is also intact (both tested for continuity).

Sounds like I need to pull the windshield wipers and disassemble the windshield cowl so that I can get to the *#$*&^ relay (I can't reach it with the cowl in the way) so that I can test it. If good, then I suppose its time to just start throwing parts at this thing (e.g. new compressor) unless the Oracle of iCarsoft tells me something useful.

kajtek1

W211 airmatic has tank in RR corner area.
Starting this topic you said that compressor is not coming when you open the door, now you indicate it doesn't work at all?
What exactly is it?

sbsyncro

There is no condition under which it is coming on. It doesn't activate at all. ever. While I was testing yesterday, I noticed that when I triggered one of the conditions that would normally cause it to activate, I could hear solenoids clicking and air escaping (I'm assuming from struts) and flowing through the system. But the compressor never came on and still won't come on.

I'm assuming that now after that testing, all the air has been depleted from the system, though I have no way of verifying since I have the driver's side on front up on jack stands so that I can get to the compressor for testing (and potential replacement).

Hope that clarifies.

konigstiger

You can test @ electrical connector for voltage input without removing compressor: http://www.mercedesmedic.com/air_sus...e_diy_problem/ see attachments to better understand system.

Oldgold

As an aside, ever since I got my car the compressor would only fire after starting, usually for no more than 2 to 3 seconds. At rest with engine off any adjustment was from the stored air in the tank ie expelling air to adjust down or sending air with an audible 'hiss' to the struts to raise a couple of centimetres or so. I assume the compressor firing on start-up is to replenish the tank. At first this hissing raising or lowering freaked me out but maybe its normal.

Will watch your progress with interest.

sbsyncro

Back to working on it again today. I had read in several places (at least I swear I had!) that there was no tank on the W211.

However, based on the information from Kajtek1 about the W211 having a tank, I was able to locate the tank and loosen a line to bleed off pressure. This forced the compressor to kick on while the engine was running. I was then able to hear air leaking out from the passenger side front wheel well.

The missing piece of info for me was the tank. I have now confirmed that the compressor is in fact working and that I have a leak somewhere in the front passenger wheel well. Probably the strut, but I want to be absolutely sure before I spend the money on a strut.

Thank you Kajtek1!

Oldgold

If you are buying Arnott might be worth clarifying if the following is correct..

https://w220.ee/Airmatic

Doesn't worry me because I'm always on 'comfort'.

Also..

"Arnott Remanufactured. An Arnott remanufactured AIRmatic strut costs about US$575, but note that it only has installed a new rubber air bags/bladders and not the shock piston seals or gas charge"

sbsyncro

I just realized I never came back and closed out this thread (I hate it when people do that!). :-)

Wanted to say that I purchased an Arnott reman OEM (AS 2246) from BMA parts in Glendale (they were fantastic to deal with by the way - GREAT customer service!) and it all went together smoothly. I had some squeaking afterwards, but it solved all the problems and was back on the road.

By the way if anyone is looking for an iCarsoft MB II scanner, I just listed the one I bought for this job in the Marketplace

Thank you everyone for your help.