Loss of AC on W212 Bluetec
Thread Starter
Junior Member
Joined: Jul 2011
Posts: 21
Likes: 0
C230
Loss of AC on W212 Bluetec
Greetings all...
My 2011 E350 BT's AC stopped working. It blows no cool air at all. There's no visible leak that I can spot in the condenser nor anything obvious on any connections. I looked for related trouble codes but none showed up (but I don't have a very sophisticated ODBII reader). I discovered that these don't have clutched compressors so listening for it engaging doesn't work. I can't find any way to reset the AC system to eliminate any hiccups of the electronic type. I found a few reset methods online but none of them work on this car. I also can't sort out how to eliminate a stuck mixer valve - for all I know the AC is working but not switching over.
I would welcome any suggestions for troubleshooting to identify what's going on before taking it to the shop.
My 2011 E350 BT's AC stopped working. It blows no cool air at all. There's no visible leak that I can spot in the condenser nor anything obvious on any connections. I looked for related trouble codes but none showed up (but I don't have a very sophisticated ODBII reader). I discovered that these don't have clutched compressors so listening for it engaging doesn't work. I can't find any way to reset the AC system to eliminate any hiccups of the electronic type. I found a few reset methods online but none of them work on this car. I also can't sort out how to eliminate a stuck mixer valve - for all I know the AC is working but not switching over.
I would welcome any suggestions for troubleshooting to identify what's going on before taking it to the shop.
MBWorld Fanatic!
Joined: Jan 2009
Posts: 9,224
Likes: 1,798
From: V E G A S
1922 Ford Model T / no OBD
Millions of threads about AC troubleshooting.
Do you have scanner who can read refrigerant pressure?
Start reading it on cold morning before engine start and then observe changes in pressure on hot afternoon.
Do you have scanner who can read refrigerant pressure?
Start reading it on cold morning before engine start and then observe changes in pressure on hot afternoon.
Thread Starter
Junior Member
Joined: Jul 2011
Posts: 21
Likes: 0
C230
Thanks for getting back. I do have a scanner and it has helped me find the two minor failures I've had with this car (a faulty Adblue heater and a fuel sending unit where a mouse chewed the wiring on one side), but I'm not showing anything coming close to AC related this time. I realize that some scanners don't work reliably on this and later models. It's hard to find a scanner that does it all it seems.
I've read a bunch of posts related to AC failures. Several talk about intermittent AC issues and a few others about relay issues and mixer problems. I have a really good indy shop and if I can't sort it soon I'll drive over and have them scan it.
I've read a bunch of posts related to AC failures. Several talk about intermittent AC issues and a few others about relay issues and mixer problems. I have a really good indy shop and if I can't sort it soon I'll drive over and have them scan it.
Thread Starter
Junior Member
Joined: Jul 2011
Posts: 21
Likes: 0
C230
Forgot to add... I can't tell if the compressor is working but I do have gauges... I'll try hooking up to see if I can get some readings. The scanner I have doesn't display AC system pressures.
MBWorld Fanatic!
Joined: Jan 2009
Posts: 9,224
Likes: 1,798
From: V E G A S
1922 Ford Model T / no OBD
I avoid hooking up the gauges as they can open another leak on the valve, while it is much easier to read the pressure by pushing some buttons on the scanner, but if you want to do it this way- it will work for checking static pressure, while harder to do it on the freeway.
Latest deal in scanners is Autel dongle for $49 and it did extensive troubleshooting on my Sprinter.
Latest deal in scanners is Autel dongle for $49 and it did extensive troubleshooting on my Sprinter.
MBWorld Fanatic!
Joined: Feb 2014
Posts: 6,190
Likes: 1,549
From: MA
2008 E350 4Matic, 2011 E350 4matic
Thread Starter
Junior Member
Joined: Jul 2011
Posts: 21
Likes: 0
C230
Good question... I'll check the temp sensor right away!
I might have to upgrade my ODB2 capability. I love this car - it's been super reliable and a real pleasure to drive (3.5L diesel with a sport package and paddle shifters can be a lot of fun!). So it's worth the investment in tools
I might have to upgrade my ODB2 capability. I love this car - it's been super reliable and a real pleasure to drive (3.5L diesel with a sport package and paddle shifters can be a lot of fun!). So it's worth the investment in tools
Trending Topics
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Is your fan in front running at high speed? I had this happen and no cool air from vents. Turned out to be over charge in the system and after letting some refrigerant out the a/c started working correctly.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Thread Starter
Junior Member
Joined: Jul 2011
Posts: 21
Likes: 0
C230
Business got in the way of diagnosing... but back at it.
Thanks kajtek1 for recommending an Autel reader - great tip. I picked up an A200M for $29 on Amazon and it did a good job of reading the Merc codes, but showed no AC faults (for anyone else with a Bluetec you download the "Benz" software and not the Benz Sprinter). I cleared and ran the car for about 1/2 and hour. While driving I put the foot down a few times and got frigid air immediately. It stayed cold while cruising around. When I got back to my garage I read the codes again. Still no AC codes. I drove it again the next day and warm air until I stomped on it - then: icebox. I read about a few other folks running into this problem - intermittent AC problems.
I'm getting suspicious of a pressure switch issue. I've had problems with them in the past getting flaky and throwing out erroneous pressures that screw things up. I can see a high pressure switch near the condenser. Looks like just a cheap diaphragm switch. I've read about low pressure hose collapses causing similar problems but I believe this was limited to W211 and not the W212. At this point it's off to the indy repair shop since best let them evacuate the system.
Assuming the system has to be opened anything else I should replace before I pay for an expensive recharge? Schrader valve, dryer, etc.?
Thanks kajtek1 for recommending an Autel reader - great tip. I picked up an A200M for $29 on Amazon and it did a good job of reading the Merc codes, but showed no AC faults (for anyone else with a Bluetec you download the "Benz" software and not the Benz Sprinter). I cleared and ran the car for about 1/2 and hour. While driving I put the foot down a few times and got frigid air immediately. It stayed cold while cruising around. When I got back to my garage I read the codes again. Still no AC codes. I drove it again the next day and warm air until I stomped on it - then: icebox. I read about a few other folks running into this problem - intermittent AC problems.
I'm getting suspicious of a pressure switch issue. I've had problems with them in the past getting flaky and throwing out erroneous pressures that screw things up. I can see a high pressure switch near the condenser. Looks like just a cheap diaphragm switch. I've read about low pressure hose collapses causing similar problems but I believe this was limited to W211 and not the W212. At this point it's off to the indy repair shop since best let them evacuate the system.
Assuming the system has to be opened anything else I should replace before I pay for an expensive recharge? Schrader valve, dryer, etc.?
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Business got in the way of diagnosing... but back at it.
Thanks kajtek1 for recommending an Autel reader - great tip. I picked up an A200M for $29 on Amazon and it did a good job of reading the Merc codes, but showed no AC faults (for anyone else with a Bluetec you download the "Benz" software and not the Benz Sprinter). I cleared and ran the car for about 1/2 and hour. While driving I put the foot down a few times and got frigid air immediately. It stayed cold while cruising around. When I got back to my garage I read the codes again. Still no AC codes. I drove it again the next day and warm air until I stomped on it - then: icebox. I read about a few other folks running into this problem - intermittent AC problems.
I'm getting suspicious of a pressure switch issue. I've had problems with them in the past getting flaky and throwing out erroneous pressures that screw things up. I can see a high pressure switch near the condenser. Looks like just a cheap diaphragm switch. I've read about low pressure hose collapses causing similar problems but I believe this was limited to W211 and not the W212. At this point it's off to the indy repair shop since best let them evacuate the system.
Assuming the system has to be opened anything else I should replace before I pay for an expensive recharge? Schrader valve, dryer, etc.?
Thanks kajtek1 for recommending an Autel reader - great tip. I picked up an A200M for $29 on Amazon and it did a good job of reading the Merc codes, but showed no AC faults (for anyone else with a Bluetec you download the "Benz" software and not the Benz Sprinter). I cleared and ran the car for about 1/2 and hour. While driving I put the foot down a few times and got frigid air immediately. It stayed cold while cruising around. When I got back to my garage I read the codes again. Still no AC codes. I drove it again the next day and warm air until I stomped on it - then: icebox. I read about a few other folks running into this problem - intermittent AC problems.
I'm getting suspicious of a pressure switch issue. I've had problems with them in the past getting flaky and throwing out erroneous pressures that screw things up. I can see a high pressure switch near the condenser. Looks like just a cheap diaphragm switch. I've read about low pressure hose collapses causing similar problems but I believe this was limited to W211 and not the W212. At this point it's off to the indy repair shop since best let them evacuate the system.
Assuming the system has to be opened anything else I should replace before I pay for an expensive recharge? Schrader valve, dryer, etc.?
MBWorld Fanatic!
Joined: May 2015
Posts: 4,037
Likes: 1,011
From: Miami, FL
2003 CL 600
I'd suspect the refrigerant control valve in the compressor has failed, they often stick and only open up properly when hit with some high rpms, often a good rev in park will make it work even. The valve is serviceable separately but not from MB, you will have to source the part from an A/C supply shop, but the valve will be ~$50 or less, vs the cost of a new compressor.
Thread Starter
Junior Member
Joined: Jul 2011
Posts: 21
Likes: 0
C230
Yeah... all it took was one strong acceleration... up to around 4500rpm and instant cold air. After that the car behaves normally. It's easy to blame a compressor but this a low-mile car and when operating the AC is ice cold. It has had no AC service since new so I'm not complaining. I'll try a can of 134a and see if indeed the system is a little low. What should I be looking at for low and high pressures at idle on gauges? The Autel A200M does report high pressure readings while running so I'll eyeball that first.
Others feel differently, but I hate opening up a factory AC system if I can avoid it. At least I have a methodical indy shop run by retired Merc mechs.
Thanks for all the great advice and help!
Others feel differently, but I hate opening up a factory AC system if I can avoid it. At least I have a methodical indy shop run by retired Merc mechs.
Thanks for all the great advice and help!
MBWorld Fanatic!
Joined: May 2015
Posts: 4,037
Likes: 1,011
From: Miami, FL
2003 CL 600
Yeah... all it took was one strong acceleration... up to around 4500rpm and instant cold air. After that the car behaves normally. It's easy to blame a compressor but this a low-mile car and when operating the AC is ice cold. It has had no AC service since new so I'm not complaining. I'll try a can of 134a and see if indeed the system is a little low. What should I be looking at for low and high pressures at idle on gauges? The Autel A200M does report high pressure readings while running so I'll eyeball that first.
Others feel differently, but I hate opening up a factory AC system if I can avoid it. At least I have a methodical indy shop run by retired Merc mechs.
Thanks for all the great advice and help!
Others feel differently, but I hate opening up a factory AC system if I can avoid it. At least I have a methodical indy shop run by retired Merc mechs.
Thanks for all the great advice and help!
If your scanner will show you all the HVAC live data, watch the compressor current, evap temperature, and system pressure. You should see the current go up, pressure go up, and temp go down. If you see only current, and no temp or pressure, but after a rev you get pressure and temperature changes with the current the same or going down, the valve is sticking closed.
System working pressures vary a bit by ambient temp, but assume 30-35ish low side, and 150-180 high side, if the system is working well and on full cold. The variable compressor will back down gradually as temperature demands are met, so it's common to see more even pressures if the system isn't working hard to meet the demands.
Last edited by ItalianJoe1; Jun 30, 2021 at 06:29 PM.
MBWorld Fanatic!
Joined: May 2018
Posts: 6,600
Likes: 6,547
From: Jakarta-Indonesia
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
I read the MaxiAP200M car coverage with version Benz v2.10, it claimed able read air conditioning data and by right you can access freon pressure data.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Yeah... all it took was one strong acceleration... up to around 4500rpm and instant cold air. After that the car behaves normally. It's easy to blame a compressor but this a low-mile car and when operating the AC is ice cold. It has had no AC service since new so I'm not complaining. I'll try a can of 134a and see if indeed the system is a little low. What should I be looking at for low and high pressures at idle on gauges? The Autel A200M does report high pressure readings while running so I'll eyeball that first.
Others feel differently, but I hate opening up a factory AC system if I can avoid it. At least I have a methodical indy shop run by retired Merc mechs.
Thanks for all the great advice and help!
Others feel differently, but I hate opening up a factory AC system if I can avoid it. At least I have a methodical indy shop run by retired Merc mechs.
Thanks for all the great advice and help!
High ambient temperature raises the refrigerant pressure in the system and now I'm thinking this is a over charge issue coming from the factory. I had over charge with the system never opened after car was made and there seems to be others at this time when parts of the country are very hot.
MBWorld Fanatic!
Joined: May 2015
Posts: 4,037
Likes: 1,011
From: Miami, FL
2003 CL 600
I realized I should have read your first post better. I just remembered when I had the over charge problem my A/C did the same thing as yours. Sometimes it would not give any cooling with idle. I had to go drive it for getting A/C to work. I also thought it is low and added 134a with the result of the fan in front starting to run very fast speed. I then let refrigerant out below the pressure it was at and went to the green range low limit on the gauge and the system started working normally.
High ambient temperature raises the refrigerant pressure in the system and now I'm thinking this is a over charge issue coming from the factory. I had over charge with the system never opened after car was made and there seems to be others at this time when parts of the country are very hot.
High ambient temperature raises the refrigerant pressure in the system and now I'm thinking this is a over charge issue coming from the factory. I had over charge with the system never opened after car was made and there seems to be others at this time when parts of the country are very hot.
If you're not using gauges to charge the car, don't add refrigerant blindly.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Mercedes may not be counting for the very hot climate in some areas and their A/C charge level ends up too high during very hot days.
And it is not adding refrigerant to fix it. It is to let some out. That is what I did and that is the only difference in the system to before it started acting up.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Well, his car CAN BE suddenly over charged if it is the first time in very hot environment. My car was several years old when it suddenly started acting like I explained in my earlier post.
Mercedes may not be counting for the very hot climate in some areas and their A/C charge level ends up too high during very hot days.
And it is not adding refrigerant to fix it. It is to let some out. That is what I did and that is the only difference in the system to before it started acting up.
Mercedes may not be counting for the very hot climate in some areas and their A/C charge level ends up too high during very hot days.
And it is not adding refrigerant to fix it. It is to let some out. That is what I did and that is the only difference in the system to before it started acting up.
Readings are: 180 psi on high side
32 psi on low side
Air temperature out the center vent 44F
Outside temperature 92 F.
Works quite well and it does a better job when I drive and get some more air flow thru the condenser in the front of the car.
MBWorld Fanatic!
Joined: May 2015
Posts: 4,037
Likes: 1,011
From: Miami, FL
2003 CL 600
The charge is based on weight, that's why you don't do it on pressures. I'm 100% sure MB tests the car in hot climate, and just warming up to 100 degrees outside isn't going to make your a/c now "overcharged"
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
A guy has a problem with A/C and asks for help. I'm trying to help by telling what I have gone thru with my car. What is your problem with that?
MBWorld Fanatic!
Joined: May 2015
Posts: 4,037
Likes: 1,011
From: Miami, FL
2003 CL 600
You're giving out bad information. I'm a tech, I do this daily. I have seen his problem, I have told him what to check to confirm. You are guessing, assuming, hacking at your car by adding refrigerant and then bleeding some off until you "fixed" it. If that worked for you, great, but don't share bad advice with people who don't know better.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
You're giving out bad information. I'm a tech, I do this daily. I have seen his problem, I have told him what to check to confirm. You are guessing, assuming, hacking at your car by adding refrigerant and then bleeding some off until you "fixed" it. If that worked for you, great, but don't share bad advice with people who don't know better.
Bleeding refrigerant to see if it fixes the problem is very easy to do if you are at all hands-on person and then adding it back if it does not bring the fix is as easy. Very low cost procedure that any DIY person can do. Does not harm the car in any way when done but can be the fix for the issues.
My car was over charged from factory no matter what you say, period. It could be the case in many cars as these are serial product items.
MBWorld Fanatic!
Joined: May 2015
Posts: 4,037
Likes: 1,011
From: Miami, FL
2003 CL 600
You can be a tech as much as you want. I am not giving out bad information. It is exact experience what I went thru. Your opinion seem to drive people to go get service from a tech, like you perhaps.
Bleeding refrigerant to see if it fixes the problem is very easy to do if you are at all hands-on person and then adding it back if it does not bring the fix is as easy. Very low cost procedure that any DIY person can do. Does not harm the car in any way when done but can be the fix for the issues.
My car was over charged from factory no matter what you say, period. It could be the case in many cars as these are serial product items.
Bleeding refrigerant to see if it fixes the problem is very easy to do if you are at all hands-on person and then adding it back if it does not bring the fix is as easy. Very low cost procedure that any DIY person can do. Does not harm the car in any way when done but can be the fix for the issues.
My car was over charged from factory no matter what you say, period. It could be the case in many cars as these are serial product items.
You extracted the refrigerant charge from your car and weighed it to confirm it was overcharged from new? Highly unlikely. You are guessing. I have seen countless cars not charged enough from the factory, particularly Japanese brands. But never seen a single car with too much refrigerant in it unless someone overcharged it during a repair.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
I'm giving diagnostic advice, not telling him to take it to a shop. He has a scanner, he can look at the info I suggested, and confirm his failure before doing anything. That's how you fix things efficiently, not by trial and error. I don't even work at MB anymore and yet I still come here on the forum to help people fix their cars, so yes it irritates me when I see people just saying random things and passing them off as true, when the person asking needs real, valid help. You can preface your statement with "this isn't the right way to do it, but here's what I did", but don't come out and say "oh the car must be overcharged, that happens a lot" when it's simply not true and most likely not applicable in this case anyway with his description of the failure.
You extracted the refrigerant charge from your car and weighed it to confirm it was overcharged from new? Highly unlikely. You are guessing. I have seen countless cars not charged enough from the factory, particularly Japanese brands. But never seen a single car with too much refrigerant in it unless someone overcharged it during a repair.
You extracted the refrigerant charge from your car and weighed it to confirm it was overcharged from new? Highly unlikely. You are guessing. I have seen countless cars not charged enough from the factory, particularly Japanese brands. But never seen a single car with too much refrigerant in it unless someone overcharged it during a repair.
