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http://www.mercedesmedic.com/ac-air-...le-codes-list/
I've been posting the link to procedure all over the forums, yet for some reason lot of members still go to sledge hammer and crystal ball approach.
Can't explain the mentality, but variable output compressors where computer operates with 7 or more sensors need to be properly troubleshoot.
On W210 the troubleshooting takes 90 seconds as you can do it on car LCD display. while W212 require scanner.
Still easy to test before you start fooling with the system.
Hooked up my icarsoft MB II scanner today. For the A/C system NO CODES AT ALL even after I on purpose lowered the refrigerant level to a point it almost stopped giving any cool air out the vents. And before this when charge was TOO HIGH as it made that front fan go screaming fast and NO COOLING AT ALL there was no error code in the system.
I was able to run data as the car was running and the evaporator temp was running at around 10.5 - 11.5 C while the air vent temp was at around 16 C.
One thing that bothers me is that the flapper valve that controls air temperature entering the car seemed to have 90% max set point. When I played with the temperature setting asking for hot air in the car this valve closed down so for cooling it needs to be open but it took 90% position when I asked for max cool. This 90% was with the value of the control unit asking for and the actual valve position value.
I'm working on this because I feel my car's air conditioning should work better than it does. I know there are limits what A/C system can do. At 95F it is hard for the system to keep it all cool but I think I had some way cheaper cars in the past that did better than this $70000 car in the same environment.
Perhaps I would just need an evaporator coil clean up, which I don't know is even possible to do in these cars...
So long story short, It was the AC pressure sensor located at the bottom of the condenser.
The dealership diagnosed the vehicle for 175 and found no trouble codes but suggest I change out the condenser, pressure sensor, ac line from condenser<->compressor. They couldn't guarantee that it would fix the issue but it was the first thing they had to do to identify the culprit and it was a 2k+ job.
Not going to pay that so I ordered parts from an authorized Mercedes dealer website for a total of 300 and replaced the parts myself.
Symptoms before fix: Fan running on high constantly but AC was blowing cold.
Results: Fan is working properly and turning on and spinning at the correct speed when AC is running.
Do you know where I can exactly locate the relay? I've been searching for hours online for the relay and unsuccessful. The vehicle was previously owned and no manual cam with it.
Your engine fan is on because you changed your air filter and forgot to plug in your mass air flow sensor. Anytime you unplug your mass airflow sensor it will trigger the engine fan to come on immediately with ignition. Plug in your mass air flow sensor I'll quit shaking your brain
It's designed to come on, ambient outside temp determines what speed it turns, hotter outside faster the fan starts. Turn A/C off and fan stops.
It needs the extra air for the A/C to cool the cabin when out side temps are high. Freon in our systems do not "Cool" the air, the freon absorbs heat, and in a high temp high pressure liquid enters the condenser in the front of the radiator where cooler air cools the freon allowing it to return to a low pressure low temp gas where it returns to the evaporator in your dash and begins absorbing heat all over again.
If your fan does not work at all, it cannot release the heat and the system fails to cool the interior of the car till the car starts moving forcing cooler air across the condenser.
Freon is R12, or R22.
Americans are very slow with proper descriptions, so as above sample shows, even 30 years is not enough to teach them new/or different technology.
Just like it took about 30 years to drop "oil change 3000" mentality, when new generation oils hit the market over 40 years ago.
Proper name for R134 is refrigerant.
Using improper names always bring confusion.
Just like famous on 5G transmission is "pilot bushing". When the name might come from lost translation, it is official WIS description in English.
Still lot of owners come with problems talking about adapters, plug, connectors and 1/2 a dozen different names.
Takes several replies in the topic to sort the mess and figure out what the member is talking about.
It's designed to come on, ambient outside temp determines what speed it turns, hotter outside faster the fan starts. Turn A/C off and fan stops.
It needs the extra air for the A/C to cool the cabin when out side temps are high. Freon in our systems do not "Cool" the air, the freon absorbs heat, and in a high temp high pressure liquid enters the condenser in the front of the radiator where cooler air cools the freon allowing it to return to a low pressure low temp gas where it returns to the evaporator in your dash and begins absorbing heat all over again.
If your fan does not work at all, it cannot release the heat and the system fails to cool the interior of the car till the car starts moving forcing cooler air across the condenser.
You have your explanation a bit off from the truth how the A/C system works.
The heat transfer is based on the phase change of the refrigerant. The compressor in the system compresses the gas form refrigerant coming from the evaporator inside the car to a high pressure hot gas. It is not high temperature liquid that enter in the condenser in the front of the car, at this point refrigerant is in gas form.
The condenser in front of the car then turns the hot gas to liquid form by removing the herat from it. This liquid then flows thru the lines to the expansion valve that is located just before the evaporator. This valve in our cars is controllable, I understand, but in most cars it is just a simple orifice and is actually called orifice tube. When the liquid refrigerant flows thru the expansion valve it evaporates and this change from liquid phase to the gas phase is what generates the cooling effect and as this very cold gas flows thru the evaporator coil inside the car it cools the air flowing thru the "air box" where the coli is located at. Then this warmed up gas flows back to the compressor and the cycle starts again.
If you have hot liquid refrigerant flowing in the condenser your system is seriously over charged and you would be in very high danger of blowing off your compressor due to hydraulic lock.
You have your explanation a bit off from the truth how the A/C system works.
The heat transfer is based on the phase change of the refrigerant. The compressor in the system compresses the gas form refrigerant coming from the evaporator inside the car to a high pressure hot gas. It is not high temperature liquid that enter in the condenser in the front of the car, at this point refrigerant is in gas form.
The condenser in front of the car then turns the hot gas to liquid form by removing the herat from it. This liquid then flows thru the lines to the expansion valve that is located just before the evaporator. This valve in our cars is controllable, I understand, but in most cars it is just a simple orifice and is actually called orifice tube. When the liquid refrigerant flows thru the expansion valve it evaporates and this change from liquid phase to the gas phase is what generates the cooling effect and as this very cold gas flows thru the evaporator coil inside the car it cools the air flowing thru the "air box" where the coli is located at. Then this warmed up gas flows back to the compressor and the cycle starts again.
If you have hot liquid refrigerant flowing in the condenser your system is seriously over charged and you would be in very high danger of blowing off your compressor due to hydraulic lock.
I see my attempt to give a generalized description of A/C theory to those who are less familiar with these systems has ruffled some feathers, so I deleted the post, and will leave it to thew "Experts" from now on.
Its okey...... Chemours who is the current owner of Dupont, is still calling their R134A refrigerant as FREON R134A.
Freon being the brand of their refrigerant, and the R134A is the type
In the old days when my Dad would want his secretary to photocopy something, he will say Xerox it please
The same as today : we say "Google It" and not SEARCH it.
In my country the very first bottled mineral water ( local brand) in 1973 is called AQUA , which is water in Latin.
By the 90s, there are a few other bigger brands, but it is by habit when we order mountain sourced mineral water ( not distilled ), we sayI want Aquaand they can bring Nestle or X,Y Z brand and no one cares....LOL.
If you speak with very old people like 90 years old in my country, they will call a camera as Kodak and outboard engine as Johnson.
So they will say, bring your Kodak and lets test my Johnson
Johnson built their first outboard engine in 1922, Mercury only in 1939.
Kodak made their first camera in 1888 wow !! 100 exposures too...double wow !!
Sometimes I know how it feels when we got confused between a brand, type of product or when a brand becomes the name of a test.
Megger is one famous test instrument brand for electrical insulation test.
I too got confused when older engineer tell me that they will do Megger Test.
I knew Megger as a brand, a very established British brand like Fluke is in America and I never realized that to many ....the word MEGGER meant Electrical Insulation Test.... LOL
From Wikipedia
"'Freon' is the brand name for the refrigerants R-12, R-13B1, R-22, R-410A, R-502, and R-503 manufactured by The Chemours Company, and so is not used to label all refrigerants of this type. These include chlorofluorocarbons and hydrofluorocarbons, both of which cause ozone depletion"
I am not much of the chemist, but my understanding is that Freon and R134 Refrigerant are having different chemicals in them, where freons harm the atmosphere much more than other refrigerants.
Oxygen and carbon monoxide are both part of the air, yet you make very specific distinction not to confuse them.
Each confusion can only bring more confusion.
From Wikipedia
"'Freon' is the brand name for the refrigerants R-12, R-13B1, R-22, R-410A, R-502, and R-503 manufactured by The Chemours Company, and so is not used to label all refrigerants of this type. These include chlorofluorocarbons and hydrofluorocarbons, both of which cause ozone depletion"
I am not much of the chemist, but my understanding is that Freon and R134 Refrigerant are having different chemicals in them, where freons harm the atmosphere much more than other refrigerants.
Oxygen and carbon monoxide are both part of the air, yet you make very specific distinction not to confuse them.
Each confusion can only bring more confusion.
I deleted the post, what more do you want? should I delete my membership too? Would that make you happy?
I deleted the post, what more do you want? should I delete my membership too? Would that make you happy?
The post you quoted was my reply to other member,
You don't need to get angry. Forum is place for disputes as well as learning experience.
Going to schools in Poland I was teach that using proper nomenclature can be crucial in the field. So I just correct something that is post out of ignorance.
I guess you won't make the mistake again, and that what counts for me.
From Wikipedia
"'Freon' is the brand name for the refrigerants R-12, R-13B1, R-22, R-410A, R-502, and R-503 manufactured by The Chemours Company, and so is not used to label all refrigerants of this type. These include chlorofluorocarbons and hydrofluorocarbons, both of which cause ozone depletion"
I am not much of the chemist, but my understanding is that Freon and R134 Refrigerant are having different chemicals in them, where freons harm the atmosphere much more than other refrigerants.
Oxygen and carbon monoxide are both part of the air, yet you make very specific distinction not to confuse them.
Each confusion can only bring more confusion.
Wiki sometimes is not very updated.
Since Freon is a brand owned by Dupont/Chemours, only them can use it how they see fit and it changes with time and thus that Wiki article is kind of useless for at least this 2023.
It is smart to keep a live a product range so famous called Freon and wh0re it to be a refrigerant of all types, as long as it has the industry ID for the refrigerant after the name FREON
https://www.freon.com/en/industries
Good move by Chemours, Freon is so famous, when I meet regular Joe they will not use the term refrigerant, they will call it FREON.
06-17-2019 | 12:09 AM
