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Bringing this back up even though its a few months old. I just replaced the compressor in my W211 E55, and this thread was the explanation for why it did not work.
The original compressor was without a diode, and the replacement included it, and of course it doesn't run!
Now that I know that the parts catalogs aren't reliable for this distinction, have any of you found a way to correctly choose the proper Denso compressor? I found a Nissens which looks correct based on the photo, if the photo can be trusted.
Bringing this back up even though its a few months old. I just replaced the compressor in my W211 E55, and this thread was the explanation for why it did not work.
The original compressor was without a diode, and the replacement included it, and of course it doesn't run!
Now that I know that the parts catalogs aren't reliable for this distinction, have any of you found a way to correctly choose the proper Denso compressor? I found a Nissens which looks correct based on the photo, if the photo can be trusted.
Thanks for the quick reply. Do you intend to check EPC or another resource? I have EPC, I just no longer trust the vendor or store catalogs. Denso's search doesn't even list my original part, US or EU.
EPC will give MB part number, not the Denso number.
Also, post a photo of the old compressor sticker, and/or the photo of the electronic control valve installed at the back.
Alternative, if the new compressor is not in the car, photo of the sticker and the valve area. If I could see the valve completely I could try find which valve matches it w/o the diode.
There are two versions of each compressor, with and w/o the diode. So swapping the same valve type for one w/o diode is another approach
Looks like I am in the same boat. Saturday, my car had A/C, Sunday, it did not. Looked at things with iCarSoft - pressures are fine (and confirmed at the fill valve - lots of refrigerant pressure) but I have a mag clutch fault.
So the question is - at 81K miles, all in Florida so the A/C compressor has been running hard for nearly all of it - is it really worth replacing just the clutch? Or am I better off sucking it up and just getting a new compressor. I am not afraid of having to refill the system, I already did that once this year to replace the pressure sensor. From eEuro, the compressor is not THAT expensive in the grand scheme of things, ~$425 for a Denso. And lots easier to do it now than wait for it to fail and send shrapnel through the system. So call it $350ish more to replace the whole thing. Not chump change, but then again in theory I might not have to touch it again for a LONG time.
I should add, I got bit by this once before. Had a Volvo where the clutch died, replaced just the clutch, then less than a year later the compressor grenaded with all the fun that results in. I spent a TON of money on getting cold air in that car.
I'm just glad it waited for me to finish driving from Maine to Florida! That would have been super annoying with no A/C, even in early November.
Kevin Rhodes
Port Charlotte, FL
'14 E350 wagon
Last edited by kevinr1916; Nov 27, 2023 at 06:08 PM.
Looks like I am in the same boat. Saturday, my car had A/C, Sunday, it did not. Looked at things with iCarSoft - pressures are fine (and confirmed at the fill valve - lots of refrigerant pressure) but I have a mag clutch fault.
So the question is - at 81K miles, all in Florida so the A/C compressor has been running hard for nearly all of it - is it really worth replacing just the clutch? Or am I better off sucking it up and just getting a new compressor. I am not afraid of having to refill the system, I already did that once this year to replace the pressure sensor. From eEuro, the compressor is not THAT expensive in the grand scheme of things, ~$425 for a Denso. And lots easier to do it now than wait for it to fail and send shrapnel through the system. So call it $350ish more to replace the whole thing. Not chump change, but then again in theory I might not have to touch it again for a LONG time.
I should add, I got bit by this once before. Had a Volvo where the clutch died, replaced just the clutch, then less than a year later the compressor grenaded with all the fun that results in. I spent a TON of money on getting cold air in that car.
I'm just glad it waited for me to finish driving from Maine to Florida! That would have been super annoying with no A/C, even in early November.
Kevin Rhodes
Port Charlotte, FL
'14 E350 wagon
the magnet is an electric part. Its life does not correlate with compressor effort.
Changed mine on W212 and still running w/o any issues
All the vehicle listed on my signature are still on the original compressors. The 2014 and 2015 have not been recharged yet. The 2008, 2012 and the 2014 are Florida only cars, while the 2015 was a Connecticut-Florida car before hand
the magnet is an electric part. Its life does not correlate with compressor effort.
Changed mine on W212 and still running w/o any issues
All the vehicle listed on my signature are still on the original compressors. The 2014 and 2015 have not been recharged yet. The 2008, 2012 and the 2014 are Florida only cars, while the 2015 was a Connecticut-Florida car before hand
I didn't say it did - but the compressor IS wearing out with every revolution it spins... It could last another decade, or it could grenade itself next week. I am not a fan of being penny-wise and pound-foolish, and given I have the tools to deal with the refrigerant, it looks easier to just replace the whole thing than fiddle around with the clutch itself. I'd probably take the compressor out of the car to do that anyway - changing it in place looks like a PITA just to save a few bucks in refrigerant that I have sitting on the shelf anyway. Unless there is more to removing the compressor than it looks - it seems very accessible with lots of room to get at the bolts and get it out of the car.
Do you need to reset anything with Xentry after replacement? Or does it self-test and clear the fault on it's own? I have access to a Xentry setup, but I will have to have it shipped down from Maine.
I didn't say it did - but the compressor IS wearing out with every revolution it spins... It could last another decade, or it could grenade itself next week. I am not a fan of being penny-wise and pound-foolish, and given I have the tools to deal with the refrigerant, it looks easier to just replace the whole thing than fiddle around with the clutch itself. I'd probably take the compressor out of the car to do that anyway - changing it in place looks like a PITA just to save a few bucks in refrigerant that I have sitting on the shelf anyway. Unless there is more to removing the compressor than it looks - it seems very accessible with lots of room to get at the bolts and get it out of the car.
Do you need to reset anything with Xentry after replacement? Or does it self-test and clear the fault on it's own? I have access to a Xentry setup, but I will have to have it shipped down from Maine.
Thanks for the reply!
Kevin Rhodes
There was no need to use XEntry. It worked once it started.
On the topic of taking the compressor out of the bay, it is not only about saving money. I am extremely conservative about opening components (open surgery) on ANY system (being a car, a computer, a piece of software, a human, etc). The less I disturb a system, the less likely to introduce new problems. Opening a good working condition AC system, you must be careful that you may need to replace the dryer/condenser as well once exposed to the environment. Be careful that no oil leaves the system, do not disturb the Schrader valve, proper vacuum, etc. Was it a PITA? sure, but the repair was under a very controlled setting.
For example, I do not take the intake plenum out when changing the plugs unless I really want to look at the valves, or being forced required to access something else.
I do work on computer software, and I would be rich if I get paid for the times I was told: "it is easier this way, nothing will be damaged, and nothing will change with my approach"
NOTE: if getting a new compressor, be careful the seller send you the correct compressor combo. I mean with the correct "diode or w/o diode" for your car. Some people have got into trouble just because the provider sent the wrong, though look like correct, compressor.
There was no need to use XEntry. It worked once it started.
On the topic of taking the compressor out of the bay, it is not only about saving money. I am extremely conservative about opening components (open surgery) on ANY system (being a car, a computer, a piece of software, a human, etc). The less I disturb a system, the less likely to introduce new problems. Opening a good working condition AC system, you must be careful that you may need to replace the dryer/condenser as well once exposed to the environment. Be careful that no oil leaves the system, do not disturb the Schrader valve, proper vacuum, etc. Was it a PITA? sure, but the repair was under a very controlled setting.
For example, I do not take the intake plenum out when changing the plugs unless I really want to look at the valves, or being forced required to access something else.
I do work on computer software, and I would be rich if I get paid for the times I was told: "it is easier this way, nothing will be damaged, and nothing will change with my approach"
NOTE: if getting a new compressor, be careful the seller send you the correct compressor combo. I mean with the correct "diode or w/o diode" for your car. Some people have got into trouble just because the provider sent the wrong, though look like correct, compressor.
Thanks, good to know it should clear itself.
I have no particular fear of working on the A/C system - I have the tools, and I have done it many times across a wide variety of cars. I already emptied and refilled this car once to change the pressure sensor. No alternative for that job. The trick for something like this is not leaving it empty for any length of time. Let enough gas out to reduce the pressure, then plug the hoses. Only a very minimal amount of air is going to get in there while you get the part swapped and everything buttoned up again. Vacuum it out thoroughly, put the specified amount of gas and oil back in, and call it a day.
I also am in no particular rush. It's not my only car.
I'm actually a computer *hardware* engineer - I have not much fear of breaking things, lol. I take apart systems while they are up, running, and in production (enterprise storage and backup, with a side of virtualization and high performance computing/networking.
@JCM_MB I hate to bring up an old thread; however, I have a 2014 E350 Cabriolet with the same M276 3.5 as your W212. Over the weekend, my A/C stopped working, and when pulling the codes, it also came up with P064515. I took it to my local Independent Mercedes Shop, and they did a leak-down test and refilled the system. I checked for leaks, and there were none, but they stated that since the clutch didn't engage, the compressor was bad, so I should replace the compressor, drier, and o-rings for $2300. I have been reviewing your posts above and really feel like I should try to replace the magnetic clutch myself, as when I Disconnected the cable from the magnetic clutch and tried to measure resistance, I got Nothing, an open circuit.
I am slowly and methodically disassembling the clutch while waiting for the new part to arrive. I have one question, though:
When I pulled off the front pressure plate, I only saw 1 shim between the shaft and the pressure plate. Do you happen to remember if you had 1 or 2 shims? It's throwing me off, as the very nice ladies in the video who have a similar compressor have 2 shims. I've already lost and eventually found the 10mm deep in the engine bay (that was a fun hour with a magnet on the borescope), and I could have missed it falling when I wiggled off the pressure plate, and since it's so small I may not have heard the "clink" if it fell.
Thank you in advance for your time.Many others and I owe you your choice of beverage!
@JCM_MB I hate to bring up an old thread; however, I have a 2014 E350 Cabriolet with the same M276 3.5 as your W212. Over the weekend, my A/C stopped working, and when pulling the codes, it also came up with P064515. I took it to my local Independent Mercedes Shop, and they did a leak-down test and refilled the system. I checked for leaks, and there were none, but they stated that since the clutch didn't engage, the compressor was bad, so I should replace the compressor, drier, and o-rings for $2300. I have been reviewing your posts above and really feel like I should try to replace the magnetic clutch myself, as when I Disconnected the cable from the magnetic clutch and tried to measure resistance, I got Nothing, an open circuit.
I am slowly and methodically disassembling the clutch while waiting for the new part to arrive. I have one question, though:
When I pulled off the front pressure plate, I only saw 1 shim between the shaft and the pressure plate. Do you happen to remember if you had 1 or 2 shims? It's throwing me off, as the very nice ladies in the video who have a similar compressor have 2 shims. I've already lost and eventually found the 10mm deep in the engine bay (that was a fun hour with a magnet on the borescope), and I could have missed it falling when I wiggled off the pressure plate, and since it's so small I may not have heard the "clink" if it fell.
Thank you in advance for your time.Many others and I owe you your choice of beverage!
Honestly, I do not recall if one or two shims on the E350; however, I did fix the ML350 clutch magnet as well a few weeks ago, and there was ONLY one shim.
I ordered those pliers based on your recommendation this morning after my local Harbor Freight sold out of all the snap pliers under $50 today. You just gave me an idea, though. I'm going to take a beach towel and shove it down under the compressor. That way, whenever I eventually drop one of the snap rings, I'll have a better chance of it not disappearing.
Last time, on the ML, I was ready with these ones https://a.co/d/eVgtMho
Taking both snap rings , the pulley and the magnet was a breeze this time.
Putting back the magnet one is still a chore though
Distance to bracket @JCM_MB Quick question does your W212 have this support bracket for the radiator fan ? While I waiting for the good set of snap ring pliers to arrive I cut down my cheap set to about 4.5 inches just to see if I could get any kind of headway here with the straight head that you recommended in your post. The good news is now I’m not into the radiator fan with the handle of the pliers.
However I keep hitting this bracket so I’m wondering if I should try to remove it to give myself more room.
It’s all a moot point if I could get a hold of this with the 90 degree head but they don’t open wide enough to do anything with the snap ring.
@JCM_MB I can't thank you enough for your help. For others, my best advice is just to bite the bullet and :
Have the car up on jack stands/ramp just to make things more comfortable.
Remove the front undertray under the radiator
Remove the radiator fan
That process won't take you more than about 15 minutes and will be worth it. You will probably do what I did and convince yourself that you can remove the compressor pulley with a 90-degree snap ring plier, which can also be used to remove the magnetic clutch. The reality is, though, that you'll need to use the straight pliers to get in deep enough to remove the clutch.
When you thought the hard part was over, you have to put it back together. After struggling with the snap ring for a while, I finally had success when I just got one side of the bottom of the snap ring in the groove, then I took a micro flat head screw driver and tapped it slowly around the ring till I saw it fully seat into place on the camera.
This is the view you will have while working on this.
The sweet reward will be that you can get the windows to condensate again when you get the system working for $70. Working like it should! I haven't seen temps this low since R-12 was much more common
Last edited by ap41563; Apr 28, 2025 at 10:42 PM.
Reason: Added more photos
@JCM_MB I can't thank you enough for your help. For others, my best advice is just to bite the bullet and :
Have the car up on jack stands/ramp just to make things more comfortable.
Remove the front undertray under the radiator
Remove the radiator fan
That process won't take you more than about 15 minutes and will be worth it. You will probably do what I did and convince yourself that you can remove the compressor pulley with a 90-degree snap ring plier, which can also be used to remove the magnetic clutch. The reality is, though, that you'll need to use the straight pliers to get in deep enough to remove the clutch.
When you thought the hard part was over, you have to put it back together. After struggling with the snap ring for a while, I finally had success when I just got one side of the bottom of the snap ring in the groove, then I took a micro flat head screw driver and tapped it slowly around the ring till I saw it fully seat into place on the camera.
This is the view you will have while working on this.
The sweet reward will be that you can get the windows to condensate again when you get the system working for $70. Working like it should! I haven't seen temps this low since R-12 was much more common
Congratulations on your work. The effort is worth every penny saved, and you did not disturb your AC system either . Enjoy it
Hi Juan, Your information on this AC coil has been wonderful for me as well. I saw where you more recently changed the coil in your ML and you inspired me to do this repair VS just buy a new compressor.
70 dollars for the coil from the same seller but with the MB plug. (I got the one you recommended. https://www.ebay.com/itm/116093161364)
My AC is freezing again.
Thank you for your post on P064515!!
Hi Juan, Your information on this AC coil has been wonderful for me as well. I saw where you more recently changed the coil in your ML and you inspired me to do this repair VS just buy a new compressor.
70 dollars for the coil from the same seller but with the MB plug. (I got the one you recommended. https://www.ebay.com/itm/116093161364)
My AC is freezing again.
Thank you for your post on P064515!!
I'm happy to hear that the information was valuable, and that another compressor did not end up in the landfill/recycled. I am sure you learned a few things on the way.
Back to enjoy your vehicle,
Hey guys i'm new to the forum and i would hope you would give me some of your experience.
I am having troubles with my ac which is not blowing cold air. It started working only when the car was cold and now it does not work in any case.
I suspected the magnetic coil which i disconnected the plug today and got open circuit but when I tried to measure the incoming voltage i got nothing.
My car has the Denso 6sbu16c compressor.
What would be the next step the magnetic clutch replaced or the control valve.
Hey guys i'm new to the forum and i would hope you would give me some of your experience.
I am having troubles with my ac which is not blowing cold air. It started working only when the car was cold and now it does not work in any case.
I suspected the magnetic coil which i disconnected the plug today and got open circuit but when I tried to measure the incoming voltage i got nothing.
My car has the Denso 6sbu16c compressor.
What would be the next step the magnetic clutch replaced or the control valve.
Hi, which specific codes do you get after scanning the AC module?
There are multiple variants of the 6SBU16C, a photo of the front of the AC compressor will help. Have you measured the resistance of the magnet coil? or the resistance of the ECV?
Hi, which specific codes do you get after scanning the AC module?
There are multiple variants of the 6SBU16C, a photo of the front of the AC compressor will help. Have you measured the resistance of the magnet coil? or the resistance of the ECV?
I have no codes. The resistance of the coil shows over limit. The ecv i jave not tested I only have this photo from the car
I have no codes. The resistance of the coil shows over limit. The ecv i jave not tested I only have this photo from the car
This is from the web
Well, if the resistance is infinite, i.e. open circuit, the magnet is toast. Have you seen the magnet replacement on sale anywhere? The one I used should be similar, but I have never worked on that specific pulley. Not certain the diameter would be same as the one I used.
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. Enjoy it 
