I have located the fuse box under the hood near the brake booster. I have removed the four or so screws to get to the secondary box. There is one black relay two yellow relays and I think one more relay. These relays are not labeled. Does anyone have a reference for the relays. They are numbered. They do not have a description next to them.
Hold on a second-----the relays that are apart of the SAM module(which was unscrewed) are that relays and not fuses, a very big difference and are NOT listed on the vehicle fuse chart. The SAM does not have a chart!!
Are you kidding me? I understand that the compressor is driven by a belt. There is a difference between a fuse and a relay. I want to know which relay to replace for the power going to the a/c compressor's electromagnetic clutch. Are you guys telling me that it only has a fuse and not a relay?
Did you ever find out were the AC Clutch relay is? Even the parts store couldn't tell me and I didn't read an answer. I look up the part online and its the same as the other relays. There is a ground wire that was worn out I replaced and the connection to the compressor itself was worn however still nowhere can I find which one is the relay to test if I need the clutch or compressor or refill freon, rebuild compressor or just replace clutch. But the pressure sensor wont engage the compressor if its to low on freon and thats it theres no getting in unless you bypass the relay and hurry up and pump in the freon. . You cant refill the freon if the clutch doesn't engage so a total catch 22. At 300000 miles I am not paying a mercedes mechanic= 1000 to 3000 to replace compressor, drier, EOE valve,condensor, temp and prressure sensors and flush the system because the cars not worth that but worth it to me to save. If i knew where the relay was I can bypass the pressure sensor and add freon or replace a couple parts (compressor 45 clutch 65) myself. Who wouldn't? At that many miles that engine is better then any toyota or honda I purchased brand new Please respond and thanks.
He.,.. he ... looks like ED took MM replies to Plutoe's insult personally.
The way I see it- Plutoe would be insulting if he would know what he is talking about. So far he didn't make his case
Just to clarify some of the issues raised here, because I have been working through the WIS for many models in the past year or so, I have realised a few MB design concepts.
1. Not everything electrical has a dedicated fuse. Often a suspect device is driven from a module which does have its own fuse. The module circuitry acts as a fuse, but you know that the module's own fuse is OK because many other features from the module are still working.
2. Details of the fuse locations (maps/charts) were originally stowed by MB for the owner inside one of the fusebox locations on the car. Most MB cars have at least 3 fusebox locations: engine bay, interior, and trunk. On certain models some big fuses, termed pre-fuses that protect modules or large consumers, are sometimes hidden in a fuse box under the passenger footwell. These will not be found without information that is not always available to a second owner, who may not have the original Owner's Manual.
3. Whereas MB does provide the Owner with details of fuse locations, they do not give details of relay locations, although the box is often called the Fuse & Relay box. Even owning a WIS does not always help with the relays location. Sometimes I can identify a relay on the circuit diagram, but can find no drawing in the WIS showing it's actual location.
4. This thread has raised the issue of a magnetic clutch on the a/c compressor that might have failed. The WIS does refer to this device (but shows no picture) on a document titled: Magnetic clutch at refrigerant compressor overheating, refrigerant compressor does not operate.
Cause: Interference voltage spikes from the Engine Control Module via direct lead on control module. The a/c compressor is switched on & off continuously, causing the magnetic clutch to become too hot and fail.
Remedy: A. Replace pushbutton control module (or) B. Replace a/c compressor.
Let me explain i am new to this conversation but I totally understand why no one is replying with answers. I am having the same problem and nobody understands why the car doesn't have the relays listed etc. You cant find them online because they only list fuses land every vin number has a different chart anyways. As I am reading along I hope to find the answer.
Yep I know that my response will no doubt create a fire storm of letters to the editor,
but I have fact and truth on my side!!
If this was a social networking site, I would understand why all the hip shooting, mumbo jumbo and puffery as you are looking to boost your posting statistics, but I repeat I don't think this is that type of site.
People with very little knowledge about the car they drive are asking for help in solving a problem.
If the person giving advice knows what he is talking about, that's great, but to just add a response, without knowing the subject, to get the posting statistics up is only self serving and serves no helpful purpose-----confusion results and the original questioner is left in the dark---------------with an unanswered question!!
If you don't know------Why not just say "I don't know, but or I believe or I suspect or in my opinion"------I respect that-----it's your opinion------but to flat out say "look in the fuse chart----when you have no idea of what you are talking about"-------because they ain't all fuses, they are relays and there is NO relay chart and there is no plug in relay in the AC circuit.
You learn about the specific relays when you look or study the horn circuit and or wiper circuit, etc.
Than again Plutoe, I have seen you talking members with little knowledge into replacing good parts. I do have my opinion what is worse
So why don't you make your case and post a diagrams or pictures to back up your knowledge?
This thread is directly related to my other post on this forum.
I cannot physicly turn the clutch with my hand and according to a local mercedes shop I should be able to turn it with my hand.
Fuses and relays is a simple place to start when having A/C problems. I really like that these cars can tell you via the climate control head values for many sensors.
In my case it is the 419 code that comes up. My refrig pressure is 6 bar= 87 psi approx. That is enough pressure (Static) meaning the compressor is not pumping) for the system to power the compressor. So low pressure is not the problem.
Only if the a/c system operates via (external) fuses & relays...
You referred to the compressor clutch as 'electro-magnetic'. The WIS calls it 'magnetic' - ie. no electricity is involved. Do you have evidence that the clutch has electrical operation, as I cannot see it on the circuit diagrams.
What you mean Ed?
The clutch is having 2 parts.
-the outer ring is having the belt on it and should turn freely with belt taken off
-the inner part is bolted to compressor shaft and should turn with hand since compressor in putting minimal resistance unless frozen. No belt removal necessary for this test.
Electrical problem figured out. Really it was not electrical at all. A test wire was hooked up to the wire going to the compressor and the system was sending 12v to the clutch. bottom line the clutch was bad. I'm replacing the compressor today. I got the part for $250 out the door. It's a OE denso part. I'm going to my friend's shop tomorrow for refilling the system. I'm leaving the other parts alone. We'll see how it goes.
A/C Compressor Relaced. Did not replace the dryer or the expansion valve. Refilled the system after pulling avacuum and holding a vacuum. I filled the system with 6oz of PAG 150 and 3 12oz cans of 134a. Lowest temp recorded at 45mph with recirculate on 47 degrees F. Ambient outside temp was 87 degrees F.
It's all academic now as you have replaced the entire compressor with its clutch. But for the benefit of others reading this thread in the archives, I'd like to correct an error on my post #18 here where I said no electrics were required for the clutch. This is wrong.
Further study of the a/c circuits shows there is a wire from pin 22 connector 2 on AAC pushbutton control module (N22) to the compressor electro-magnetic clutch on the compressor (A9). This must be going to item A9k1, which your diagnostic reported had failed. :thumbsup:
I'll keep you guys updated on how long the sytem will work based on just replacing the compressor. I do agree with the proper proceedure of replacing the dryer, the pressure regulator. A flush and a fill is fine. I did what needed to do. Thanks for all of the help from everyone on the forum!
For W210 cars, there is no such thing as a "conventional" compressor clutch relay. The clutch is controlled by the climate controller, and a relay function (solid state switch) is inside the controller. The clutch is not turned on and off to regulate the cabin temperature, but it is constantly turned on, whenever the a/c is turned on.
I asked the model and model year of the car, to make sure we talk about the correct climate contrl system.
mrboca is your quickest path to resolution. The car itself can likely tell you what’s wrong but mrboca needs to know what car you have to guide you to and through the diagnostics.
My car is E320 year 2000. I was told that it is a direct contact ran by the serpentine belt. I know the temp and pressure sensors both control the compressor. If they say hey not enough freon they cut off the compressor. If the compressor or clutch burn up the serpentine belt will still go but the clutch will not engage no matter what you do. You can try to hot wire the pressure sensor but if the compressor is done it wont engage. My codes did read B1233, B1232, B1418, and B1419 and if I hit a bump the compressor would work This worked for a year or so then it wouldn't. The I put a block of wood on my relays (dont ask some guy on you tube) but it worked for another year. Now its deader then a door nail. Here is the twist I got all codes to clear but the B1419 and for some reason my fuse 20 (50amp) engine fan is dead too. Why? There is no power even coming to the wire but there is power at the fan. How is that possible? How is there power at the fan but at the fuse box nothing. Makes no since. HELP!!
I failed to mention that the connection on my compressor took some abuse since the bottom cover was lost by the tire guys. I replaced this connection (rewired) to have a much tighter fit but this did nothing as well. I did notice that there was 5 rocks in the home of the condenser but no holes visual. FYI. The temp and pressure sensor both are active with power.
The compressor wiring from the climate controller module ( the module with the display in your center dash) first goes to the relay module at the passenger side under the hood (where fuse 20 is), and is cross connected there and then goes to the compressor. In other words, it is not a direct wiring. So the wooden block on the relay module is to press on a a loose and maybe corroded connector that goes to the relay module which kept the connection going. So any bump loosened the connector disconnecting he compressor wiring. You need to take a close look at the connectors to the relay module (maybe a mechanic can do it for you) and make sure there are no corroded connector (usually due to water intrusion from the channel between the hood and the fender especially if the module lid is not properly installed. The same story with fuse 20 which should be 30 amps anyway.
The fuse 20 may be blown. Visually check it and measure power on both sides of the fuse (the tabs on each side). The fan is not powered by fuse 20. This fuse powers the fan control module which then powers the fan with different duty cycles (pulsed) to control speed. The fan may have power on it but not ground. Else it would have worked, right ? The power may be coming from some other power source that goes to the control module (only when the key is in position 2 (run). You need to make sure that fuse 20 is powered and not blown. Then you can take the next steps.
Compressor not grounded and wiring on fan is shot. In fact all the wiring in this car is falling apart. OMG. Thanks for the help. I dislike wiring but gotta do it.
IIRC B1419 means open circuit at the clutch. Can you spin the face of the compressor by hand? If not, the clutch circuit probably blew because the compressor is seized. I don’t think there’s a practical way to reset the clutch.
mrboca, I think it’s a 30A fuse for aux fans ahead of the condenser. It’s a 50A fuse for single fan behind the radiator as in ‘00 E320.
It may mean the fusible link in the clutch coil is open, or it mean the connector or wiring is bad. The poster indicated that the compressor worked on and off, so it is more likely a bad connection in the wire but checking if the compressor has seized will not hurt .
My wiring diagram shows 30 amps for fuse 20 for both case (with N65+M4 and N76+/M4/3)
How can the compressor not be grounded if it’s bolted to the block? Maybe a bad ground wire from the clutch to the compressor housing, but you’d have to drop the compressor to see that.
Yeah, there is a ground wire from the coil that goes and bolts to the compressor (see the picture at the top of the compressor with a Phillips-head bolt grounded wire).. If removed, or loose, there will be no current flowing, and you will have the 419 code. The compressor itself is grounded by its body bolted to the metalwork.
Yes, now I get it the light bulb in my head has heated up. Thanks you guys!!! I like to know the ending so I will give you my outcome within the next week.
IIRC B1419 means open circuit at the clutch. Can you spin the face of the compressor by hand? If not, the clutch circuit probably blew because the compressor is seized. I don’t think there’s a practical way to reset the clutch.
mrboca, I think it’s a 30A fuse for aux fans ahead of the condenser. It’s a 50A fuse for single fan behind the radiator as in ‘00 E320.
Yes I can spin the clutch on my e320 by hand easily both ways. Its not rusted or looking bad and there is still a gap or standard gap on the clutch. When I move it by hand it doesn't sound like the bearings are bad. The face of it doesn't pull out its solid. Lastly, at time of death it never mad any crazy noise like it was going to die or dying and no oil leaking out of the compressor. But yes there was bad wires and frustrating room for play. I will remove the compressor and rebuild it and add a new clutch which will provide solid new ground and wires. I will also check the fuses and measure ohms. Give me a week and i will update.
The compressor wiring from the climate controller module ( the module with the display in your center dash) first goes to the relay module at the passenger side under the hood (where fuse 20 is), and is cross connected there and then goes to the compressor. In other words, it is not a direct wiring. So the wooden block on the relay module is to press on a a loose and maybe corroded connector that goes to the relay module which kept the connection going. So any bump loosened the connector disconnecting he compressor wiring. You need to take a close look at the connectors to the relay module (maybe a mechanic can do it for you) and make sure there are no corroded connector (usually due to water intrusion from the channel between the hood and the fender especially if the module lid is not properly installed. The same story with fuse 20 which should be 30 amps anyway.
The fuse 20 may be blown. Visually check it and measure power on both sides of the fuse (the tabs on each side). The fan is not powered by fuse 20. This fuse powers the fan control module which then powers the fan with different duty cycles (pulsed) to control speed. The fan may have power on it but not ground. Else it would have workedI right ? The power may be coming from some other power source that goes to the control module (only when the key is in position 2 (run). You need to make sure that fuse 20 is powered and not blown. Then you can take the next steps.
ok I will turn the car on and check fuse 20. When the engine gets to temp I know the fan doesn't kick on but i will measure. Fuse 20 didn't have corrosion but others did what it did have was (im guessing) yellowish blue like maybe high heat marks.
Yes I can spin the clutch on my e320 by hand easily both ways. Its not rusted or looking bad and there is still a gap or standard gap on the clutch. When I move it by hand it doesn't sound like the bearings are bad. The face of it doesn't pull out its solid.
At time of compressors death it never made any crazy noise like it was going to die or dying. No oil leaking out of the compressor but really bad fitting on the connection so I replaced and rewired but this did nothing. When I tried to add freon the can said see mechanic (it did).
I will add a new clutch to the compressor (this adds new wires and ground). I will also check the fuses and measure v/ohms. Give me a week and i will update. Thanks you guys big help.
Sorry for the delay but I ended up hitting a deer with my Mercedes putting a hole in my condenser, however, after replacing bumper light hood (not the radiator) found that my issue with my AC freezing up after hitting a bump would sometimes come on. I found the issue was with my radiator fan. Im not joking!!! Here's a written visual.....The carbon brushes on the fan got curved seriously sharp curves. With these sharp curved brushes spinning around the motor with little gaps the now curved brushes from wear got stuck in the gaps of the copper magnet motor. (Update for everyone just joining in is that when i hit a bump my AC came on until finally it froze up) Also, the bearing wasn't in grand shape and the plastic piece was frozen to the spinner. I replaced the brushes with a part from amazon that actually goes to a milwaukee etc drill (called the carbon brush card assembly aeg M18/18V). When this part arrived I replaced it and greased the bearing cleaned it up and my issue is now gone....... Thank god..... and thanks for everyone's help.....
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Mercedes-Benz Forum
7.6M posts
693.6K members
Since 1999
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!