Airmatic pump running constantly
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2010 GL450
Airmatic pump running constantly
Just had the valve block and compressor replaced on my 2010 GL450. The malfunction light had come and was told the block was leaking and the compressor had worn out from running so much. Problem is now the compressor runs as soon as the car is turned on. Started it tonight and let it run for a few minutes and it never stopped. The car wasn't sagging at all when I started it. I hit the raise car button and it raises up no problem. I hit the button again to lower and it said lowering but wasn't going down. The compressor was still running. Turned the car off and the suspension lowered but the compressor ran for about a minute before stopping. I have had all four air struts replaced in the past year. Please help as I am wanting to trade this car ASAP. Also the compressor sounds like it running a thousand miles an hour. Much louder than I ever remember. Also it is a MB compressor not aftermarket.
Thanks
Thanks
MBWorld Fanatic!
Joined: May 2015
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From: Allentown, PA
'08 GL 320 CDI
Agree with the above. And before you condemn MB on this one... For one, MB doesn't make the relay. BUT, probably most importantly, a logical reason for this relay to "melt" to the closed (on) position is that the compressor was left running constantly so long. Off hand, I forget which relay it is, but I believe it's one of the ones under the hood on the starboard side. Check your manual - I believe there's a separate sheet showing fuses/relay locations. Maybe in 2010 it's right in the manual?
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2010 GL450
I didn't check the relay. Started it the next morning and realized it was the radiator fan that was running full speed for some reason. Anyway let it run for awhile and it worked itself out. Seems the airmatic is finally working like it should. But now the check engine light is on and giving a p2004 code. Think it is time to trade! Thanks for all the responses.
MBWorld Fanatic!
Joined: May 2015
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From: Allentown, PA
'08 GL 320 CDI
Boy, you give up quick, huh? 
How long have you had the car?
What does the code mean?
You mentioned replacing the struts and it came across as a "complaint" about the vehicle. You do realize that the main component of an air strut is rubber, right? Rubber goes bad... do you get upset when tires wear out? Do you get upset when windshield wipers wear out? Struts are a normal, "wear and tear" item. If you did some research on them before you bought, you probably bought the Arnott's? Arnott offers a lifetime warranty.
Take some deep breaths - you got all riled up about the compressor, yet it turns out you misdiagnosed that. Relax... get things under control... don't jump to conclusions. Sure, you may very well still have an electrical issue (car didn't "air down", possibly and issue with the fan), but slow down and figure things out. Trade it if you want, but think it through, logically, first. It sounds like you might do best to have a qualified mechanic take a look at it for you.
How long have you had the car?What does the code mean?
You mentioned replacing the struts and it came across as a "complaint" about the vehicle. You do realize that the main component of an air strut is rubber, right? Rubber goes bad... do you get upset when tires wear out? Do you get upset when windshield wipers wear out? Struts are a normal, "wear and tear" item. If you did some research on them before you bought, you probably bought the Arnott's? Arnott offers a lifetime warranty.
Take some deep breaths - you got all riled up about the compressor, yet it turns out you misdiagnosed that. Relax... get things under control... don't jump to conclusions. Sure, you may very well still have an electrical issue (car didn't "air down", possibly and issue with the fan), but slow down and figure things out. Trade it if you want, but think it through, logically, first. It sounds like you might do best to have a qualified mechanic take a look at it for you.
Last edited by DennisG01; Oct 31, 2017 at 09:04 AM.
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2010 GL450
That code is for the intake manifold flapper stuck open. MB wants to replace the entire manifold because the plastic part they put in it broke. You can imagine what that costs.
Don't know why you thought I was complaining about the air struts. It was just a statement. I know they are made of rubber and did replace them with arnott struts. Don't know why the fan was running like it was but fortunately it hasn't done it since. I wrongfully assumed it was the compressor because that was just replaced. That is the third compressor in the past year.
Didn't mean to offend anybody by wanting to trade the car but I have put several thousand dollars into it over the past year and just don't feel like I want to keep putting money into it. Now I have the intake manifold to deal with and today they told me that there is engine coolant temp sensor code and an evap code that is showing up too.
Also, the driver's side mirror turn signal is out. Does anybody have any idea how much that is to fix?
Thanks again for all the help. I wouldn't know anything about this car if it wasn't for this forum.
Don't know why you thought I was complaining about the air struts. It was just a statement. I know they are made of rubber and did replace them with arnott struts. Don't know why the fan was running like it was but fortunately it hasn't done it since. I wrongfully assumed it was the compressor because that was just replaced. That is the third compressor in the past year.
Didn't mean to offend anybody by wanting to trade the car but I have put several thousand dollars into it over the past year and just don't feel like I want to keep putting money into it. Now I have the intake manifold to deal with and today they told me that there is engine coolant temp sensor code and an evap code that is showing up too.
Also, the driver's side mirror turn signal is out. Does anybody have any idea how much that is to fix?
Thanks again for all the help. I wouldn't know anything about this car if it wasn't for this forum.
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MBWorld Fanatic!
Joined: May 2015
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From: Allentown, PA
'08 GL 320 CDI
"Complaining"... I guess it was just the way it worded along with the rest of the posts. But then, we can only respond based on words - we aren't talking face to face so there's no "tone of voice" or "inflection". No biggie.
I do understand how you can feel when faced with a number of repairs in a short time - feels like the old saying "When it rains, it pours".
3 compressors... that's very odd. It makes me wonder if, in fact, the relay is sticking. If it sticks closed, it causes the compressor to continue to run and it's hard to hear it running (to verify it's running longer than it should) at anything above about 25mph (at least on my car). Maybe it would be a good idea to replace the relay? And while you're at it, replace the fan relay as well. Just because it "appeared" to have fixed itself, doesn't mean it's REALLY fixed, you know?
Will your dealer stand behind the work they did recently? Maybe it's time to find a good independent mechanic that is familiar with German cars and has the tools/computer/diagnosis equipment? Or, at least get a second opinion regarding some of the other things.
Mirror Light... I haven't done it (yet), but from the little research I have done I believe it's a pretty quick job - maybe 20 minutes, tops? Try googling/you tube - I bet there's info on it. My AllData subscription says .4 hours to replace the mirror motor - can't imagine the light is much different, if it all.
I do understand how you can feel when faced with a number of repairs in a short time - feels like the old saying "When it rains, it pours".
3 compressors... that's very odd. It makes me wonder if, in fact, the relay is sticking. If it sticks closed, it causes the compressor to continue to run and it's hard to hear it running (to verify it's running longer than it should) at anything above about 25mph (at least on my car). Maybe it would be a good idea to replace the relay? And while you're at it, replace the fan relay as well. Just because it "appeared" to have fixed itself, doesn't mean it's REALLY fixed, you know?
Will your dealer stand behind the work they did recently? Maybe it's time to find a good independent mechanic that is familiar with German cars and has the tools/computer/diagnosis equipment? Or, at least get a second opinion regarding some of the other things.
Mirror Light... I haven't done it (yet), but from the little research I have done I believe it's a pretty quick job - maybe 20 minutes, tops? Try googling/you tube - I bet there's info on it. My AllData subscription says .4 hours to replace the mirror motor - can't imagine the light is much different, if it all.
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Thread Starter
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2010 GL450
The second compressor failed due to the leaking valve block. At least that was what I was told. Then supposedly that compressor was bad because the suspension malfunction was back on before I could drive back home. So far so good for the airmatic. I did let it run in the driveway for a while and I don't here the compressor running. I am wondering if the engine coolant sensor code had anything to do with the fan running so fast. I found the part for the mirror online and will probably try and tackle that myself. Have a few people calling about the vehicle already so hope I can all this sorted out soon. Love the Mercedes but we really need something that seats eight since we haul around 6 kids under 8 very often!
Thanks again
Thanks again
MBWorld Fanatic!
Joined: May 2015
Posts: 1,932
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From: Allentown, PA
'08 GL 320 CDI
Yeah, there are times I miss my old '98 Suburban (diesel) with the ability to seat 3 in that back row. But man, the Merc sure does ride nice! 75MPH in the Suburban isn't exactly "quiet"! If only our kids didn't have friends... 
There are others on here with much more technical knowledge than me, but I think your thought of a flaky coolant sensor causing the fan to run is certainly, at the very least, worth pursuing. I remember testing (older cars) sensors with a DVM - maybe the same can be done with this one, before just replacing it. BUT, I'd also try removing and cleaning the contacts first - just to be sure.
There are others on here with much more technical knowledge than me, but I think your thought of a flaky coolant sensor causing the fan to run is certainly, at the very least, worth pursuing. I remember testing (older cars) sensors with a DVM - maybe the same can be done with this one, before just replacing it. BUT, I'd also try removing and cleaning the contacts first - just to be sure.
Senior Member
Joined: Mar 2009
Posts: 401
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From: CT
GL 450, 993TT, Cayenne Diesel, 964C4
Originally Posted by dhuston99
That code is for the intake manifold flapper stuck open. MB wants to replace the entire manifold because the plastic part they put in it broke. You can imagine what that costs.
Dealerships tend to replace the intake manifolds because intake manifolds also get carboned up due to the exhaust gas recirculation(egr.) The flaps open and close for egr.
If you like the car, then find a sprinter service mechanic to work on the car. I was quoted $900-$1000 labor to replace the manifolds. Waiting on another shop to just dismantle and decarbon the manifolds. The manifolds are $1100 online and associated gaskets and new swirl motor is about an additional $250.
