When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hi, I'm having the same issue with my W212. It blows what feels like AC cold air instead of warm air. I suspect the auxiliary coolant pump is playing up...
Hi, I'm having the same issue with my W212. It blows what feels like AC cold air instead of warm air. I suspect the auxiliary coolant pump is playing up...
I'm the OP and I never got it resolved. The dealer would never acknowledge there was a problem despite 45* air blowing out of the vents when it was in the low 50s outside. I'm not convinced anything is wrong other than some sort of programming issue. It seems like just a mixing problem to me. Coincidentally my A/C stopped blowing cold air all of a sudden a couple of weeks ago so I'm going to have my independent shop see if they have any insight on the mixing problem when they fix the A/C. I'll report back if there's any news.
I'm the OP and I never got it resolved. The dealer would never acknowledge there was a problem despite 45* air blowing out of the vents when it was in the low 50s outside. I'm not convinced anything is wrong other than some sort of programming issue. It seems like just a mixing problem to me. Coincidentally my A/C stopped blowing cold air all of a sudden a couple of weeks ago so I'm going to have my independent shop see if they have any insight on the mixing problem when they fix the A/C. I'll report back if there's any news.
Did you try using manual settings? mine blows hot air from the center vents all the time I have floor and vents selected or floor and defrost selected, even the vents only selected it's hot air if I turn the temp up, I had a stuck flap on my '01 C240 and I got cold air out the center vents, dealer fixed then just fine. I never use automatic.
Did you try using manual settings? mine blows hot air from the center vents all the time I have floor and vents selected or floor and defrost selected, even the vents only selected it's hot air if I turn the temp up, I had a stuck flap on my '01 C240 and I got cold air out the center vents, dealer fixed then just fine. I never use automatic.
That's correct that the problem is in the auto mode. If I turn the temp up sufficiently it will blow warmer air but then the temp setting is way way higher than I want.
That's correct that the problem is in the auto mode. If I turn the temp up sufficiently it will blow warmer air but then the temp setting is way way higher than I want.
Mine holds the temp setting even in manual, I turn the temps to 69 and fan to #1 , blows hot air when cold and when it warms up it cools down and holds at 69. My wife turns her side to 72 and air is warmer on her side, we do this winter and summer. My first Benz in "91 had auto mode as did my other 7 Benz's, never used " Auto" in 29 years, on my 10th and 11th Benz's now. I never use Auto wipers either, they cycle way too much, just some idiosyncrasies of these cars.
Last edited by pierrejoliat; 11-30-2020 at 11:25 AM.
Anyone able to source a good heating system diagram for the W212 E200. I'm interested in the coolant flow via the parking axillary water pump and how that water is circulated in the cabin heater matrix.
it's getting colder and my car is putting out cold AC air like a fridge! 😞
Anyone able to source a good heating system diagram for the W212 E200. I'm interested in the coolant flow via the parking axillary water pump and how that water is circulated in the cabin heater matrix.
it's getting colder and my car is putting out cold AC air like a fridge! 😞
It is my understanding the US cars no longer have a "Rest" feature, my old one did, but not the last four. The Euro guys do though I believe.
That's correct that the problem is in the auto mode. If I turn the temp up sufficiently it will blow warmer air but then the temp setting is way way higher than I want.
With all do respect intended, maybe read through the HVAC section in the manual, it may help you determine how the system is supposed to work and hopefully what you perceive to be non-functional might turn out to be how the car is supposed to work?
That's not working either despite being on Rest mode. Something of is up with the heating system.
Ok, three questions;
When you go to manual and you turn on vents only and turn the temp up to 80 does it blow hot air? {engine running at operating temperature for all three questions]
When you go to manual and select floor and vents, do you get hot air out of all vents and floor registers?
When you use Auto does the A/C light come on so you're running the compressor?
Ok, three questions;
When you go to manual and you turn on vents only and turn the temp up to 80 does it blow hot air? {engine running at operating temperature for all three questions]
When you go to manual and select floor and vents, do you get hot air out of all vents and floor registers?
When you use Auto does the A/C light come on so you're running the compressor?
No
No
No, it's in REST mode, but despite this it still turns on.
I'm going to try to unplug the A/C by removing the fuse or compressor plug and see what happens.
No
No
No, it's in REST mode, but despite this it still turns on.
I'm going to try to unplug the A/C by removing the fuse or compressor plug and see what happens.
Wow, I'm guessing here but sure sounds like the heater control valve, the last one I changed was on my '03 S500, it was under the wiper assembly on the firewall, it was stuck closed, surprising because here we use heat eight months of the year.
2006 E500 4matic Wagon, 2014 e63 S AMG 4Matic wagon
Mine is a W211, but I think concerning this topic they are the same.
I have exactly all the symptoms and all various setting results suggested earlier, like AUTO vs. Manual, etc.
I wanted to add this:
I have a Foxwell scanner that allows (inter)active controls of all systems. I am able to run the heater pump and control valve from the scanner and know they work. I can also read and control all vent flaps positions individually, etc. When I perform an “blast heat from upper vents (all dash vents)” they all do blast hot air.
Then in normal operation on AUTO, it’s back to cold or rather cooler air from the center vents.
Since it seems to be a programming issue (if it is an issue at all), just out of curiosity I replaced the Air Pollution Sensor, which I read somewhere also controls the vent flaps. No difference.
Anyway, no advise offered, just my 2 cents of info.
I have exactly the same problem with my W212 (2009). It takes really long time to get warm air (like after the first 18 km) while the engine seems to be on its service temperature. I usually choose the manual heating and choose the vents and the foot zone to get warm air. After a while you notice cold air coming from all points. This takes place in a returning pattern which is very annoying in the cold weather...
I will go to my garage anyway but this does not seem logic to me... what would be the problem?
Man, I had kind of the similar problem. It began with observing a white smoke coming from the right side of the engine cabin. The engine temperature was still 85C as usual. I thought that the particle filter was regenerating as the first idea of my garage as well. I did not made any link with any anomaly with coolant.
After one day, I started to observe the inside heating going very slowly (like after a mileage of 20 km). After 2 days the heating totally failed to start while the engine temperature was still at 85C. However I noticed the the engine temperature going from 40C to 85C just in one step. Usually, this is going gradually! This was strange to me. The 3th day I decided to go to the garage. There, we found out that the coolant circulation wheel was dying, meaning insufficient circulation speed of cooling liquid. This caused temperature increase of the coolant which resulted in pressure relief the first day apparently. So, the coolant level was probably decreased as well which I did not notice on time. As the cooling circulation is also responsible for the inside heating mechanism, insufficient circulation of cooling liquid could not help sufficient heat exchange in the heating mechanism for the inside heating.
And, during this whole period, I did not observe engine temperature going above the dangerous levels(>85C) and the coolant level alarm did not take place.
We did renewed the problematic wheel but I remain with the fear that the engine might have suffered damage which we might not observe at the moment. I can not understand how the engine temperature stayed at the acceptable level with significantly decreased coolant levels. There is no way to test any possible damage neither, my garage said. If there was any damage, I would observe this immediately, they said. Have I been lucky or the damage will manifest itself soon?
recirculation wheel
Last edited by nostress man; 12-13-2020 at 11:00 AM.
Yes a water pump will do that, when the engine got to operating temp the thermostat opened allowing the really hot coolant to escape to the radiator, without mechanical help then the coolant from the bottom hose being much cooler was sent to the engine through gravity, without the water pump moving coolant mechanically, the heater core was not getting flow or a minuscule amount which would not be enough to heat the cabin. My 2 cents.
" My 2 cents. " What is the meaning of this expression?
Means "just my opinion" so "take it with a grain of salt" another expression that means similar, meaning I"m not an expert, but I may have some insight.
Common American slang, we have a million of them! we also have accents, it's easy for an American to tell just what part of the US you're from, just like German.
Last edited by pierrejoliat; 12-13-2020 at 01:56 PM.
After changing the water recirculation wheel, I observed the coolant level was still decreasing.I went back to the garage and we found out a leakage in the connection point of a hose as shown in the below picture. So, we had to change this hose as well.
I steal remain with the question how the engine could survive with significantly decreased level of coolant (see my previous post as well.). The temperature never showed any overheating.
01-28-2019, 11:49 AM
