Hi everyone,

Sorry I'm new and already giving you guys trouble. But if I can get any help regarding this matter, it would be highly appreciated.

I am currently having problems with the air conditioning. It seems that the right side (driver side) is blowing hot air instead of cold air, while passenger side is blowing cold air like it is supposed to.

A mechanic has tried to clear it manually using a scan tool but that only fixes the problem temporarily, only to return once again pretty soon. The scan tool he showed me was a refrigerant sensor throwing errors. However, he cannot be certain whether that is REALLY the problem (apparently scan tool can only do so much). After that is replaced, if it doesn't fix the problem, it's a waste of good money.

Can anyone make any recommendation? Any suggestion? Any of your input would be highly appreciated.

Thanks to everyone in advance!

 

What code did it store?..that will help you to fix the problem...

 

Hi thanks for the reply.

The mechanic showed me an error code 9201. This result was shown using his scan tool called X431.

Appreciate your help!

 

The cause could be low refrigerant level. If so, the system should be checked for leakage.

 

Hi there,

Thanks a lot for your response. The error code does go with a comment saying "check refrigerant level", but somehow I doubt that.

if there is a leak, let's say, shouldn't both side become warm? In this case only the driver's side is blowing warm air.

Very weird to me.

Thanks a lot for your help though. Much appreciated

 

I have the same issue on the E500. Hot air blowing on the driver side and cold on the passenger. Has anyone else experienced this issue or known the fix for this problem. The car is now out of warranty.

 

if its blowing cold on one side and hot on the other its a vent door that is messed up.. the blender or the actuator will need repair/repacement.....i am not sure how to repace it in a mercedes but most cars requie the dash to be removed and then replave the part - your probably not gonna like the price on repair -- interested when you get your correct diagnosis...

 

I've seen a few threads here stating that the AC is cold in the front vents(driver & passenger) but hot in the rear vents. The problem is related to a duovalve/change over valve. I'm not sure if that's related to my AC problem.
Hayseed, thanks for the suggestion. I'll do some research on vent actuators.

 

I guess anything is possible but the most likely reason for cold on one side and less on the other is from post #4. Faulty flaps could do it but I believe I've seen one post talking about a flap issue. The heat exchanger shutoff valve would not make one side colder than the other, the rear versus front is a different issue.

 

this is a classic symptom of low refrigerant level. These cars are designed to blow hot on one side/cold on one side if refrigerant runs low!

You do have independant vents (pass and driver) so its NOT the vent door. That may have been the case if you had an older chevy.

Go get it topped off - usual A/C checkup is 1/2 hr labor and cost of refrigerant at dealer so you can probably get by with 100 bucks or less if you don't have a major leak.

the valves for Hi and Lo sides leak minor gas by design. make sure the caps are tight! if you put couple drops of water on them you can probably see the bubbles coming off. the tight caps keep the system sealed.

don't waste your time on diagnosing further - get refrigerant!

 

That's interesting. It's possible that the climate control system is designed that way. However, the passenger side is very cold, it doesn't seem to me if the refrigerant is low. If it's low, it should not be cold at all, regardless which vent the air is coming out unless there are two AC systems. I will check out the refrigerant pressure with a gauge that can be purchased from Kragen or Autozone for $15. No need to bring it to the dealer for pressure check.

 

This symptom is well known - Call any indy and they will instantly tell you what it is.

I have had personal experience with a friends 98 e430 doing this now for two years -

every 4 months or so, it drops enough refrigerant to show this symptom(start blowing hot at driver - very cold at pass side).

So my friends solution is to buy the refrigeration kit and add one can of refrigerant when it does that - I think its cheesy - he should get the leak fixed - but its his car and money. once refrigerant is addedm, its good for 4-5 months.

the guy has had the car since 2000 and is still doing the same.

Like I said, its pretty well known. If you search this forum alone, you will probably hit 10 or more threads all concluding to same reason - low refrigerant.

 

Any way we can get rid of this problem once and for all? Is there a single part that can be replaced?

I'm guessing not....

 

The problem is a refrigerant leak... it could be anywhere in the system.

 

Actually, its not expensive at all - MB air conditioning system is like any other car such as Lexus, Nissan etc. take it to an A/C place and have them test for the leak - they put in a dye to find the leak. Ususally this service is anywhere between $39 - $59. If they find the leak, they will fix it and charge you for the extra refrigerant circa $12 a can or so (you may need 1-2)

Once leak is found which is usually a joint, they seal it. It is very rare to have a pipe leak from middle.

If you take it to MB dealer ship this should be no more than $200-$250. Talk to your service advisor. but I would just take it to any automotive repair/ A/C shop

 

I had a similar issue.. The problem with me was the rear vents would start to blow cold air but after about 2 minutes it would start blowing hot air. I brought it to MB and they found a shut off valve stuck in the open position.. they replaced the valve and everything is back to normal.

 

yo i have a 97 e300d with same problem of diff temps ea side. the consensus is lo refrig. lo and behold, the simple solution is the correct. Thanks soooo much

 

+1 Classic W210 & W211

 

I have read through a number of posts, but cannot any guidelines to solve my problem. My car's air conditioner do not cool the car very effectively. I have checked all the filters,the one in front of the fan and the two carbon filters at the passenger side, which are in a good condition and clean. I have tested the system without the filters as well. The air conditioner system was pressure tested and refilled, and every thing tests 100%. The problem is that it is not effective and the last person who worked on the system told me to accept it and that all the cars are not the same. This is the first M-B that I have owned with this type of problem and I cannot accept it. Is there any advice where I can look for a problem? Can you also give any advise with regards to the back vents' airflow, because they are so weak that you can feel the front centre airflow stronger in the back than the air coming from the back vents.

Thanks in advance

 

You have abetter chance of getting replies if you start a new thread instead of posting in this one. From your post, however, I can think of two things that might help. #1, there are rotary knobs by each vent in front - make sure they are rolled all the way to showing "blue" color on them. This is an air mixer - regardless of A/C setting, the air coming out will be normal )not cold) if these are set to not show blue (in my car interior is beige, and the knobs are beige as well. if someone turns them from blue to beige setting, I do not notice it for days).

Similarly, the one in back (rotary knob by vent) does something interesting - it shuts the vent at beige setting so you can control volume of air coming out of it). I canbet, that one is turned all the way to other direction minimum flow).

If these are ok, then I would check Freon level. On my 2004, I have some extremely slow leak where I have to put in one can eevry 2-3 years. It never fails to cool, just not ice-cold.

finally have your compressor checked at a local shop or better,a the dealer. Take your car to your local dealer and talk to a service advisor (SA). My experience in the past has been very nice. for both times my A/C felt les cooling, they diagnosed it for free!

 

This is the way I would go. Most a/c systems on cars with mechanical ceramic/carbon type seals new leak up to 2 oz/yr of freon and this is considered normal and almost impossible to measure.

If the car is 5 yrs old with a perfect system it could have lost 10 oz of freon but still be "normal" with no other leakage other than seal.

A 2008 model could be down 8 oz or more and still be an ok system and this loss of freon would cause improper cooling.

Consider just adding freon to top off the charge then check for leaks. I would then just drive and if you make 3 months all ok then it was just normal seal leakage.

My 2003 needed topping off in 2009 6 yrs old and hasn't needed freon since.

My 1999 Corvette needed topping off in 2007 no leaks there.

So don't get in a hurry to do something, just top off and then evaluate.

 

Thank you for the replies. Moby, I checked all the thump wheels as suggested, and it was fully opened. I closed them to check if they do operate correctly, and it seems that they are not the problem. Sitting in the front seat in the most backward position, I hold my arm about 6" from the rear vents and can feel the air coming from the front much stronger than the air coming from the rear vents. I made sure that all the front vents was open, to prevent the front air to be stronger at the centre vents.

With regards to the gas, the gas were pumped out (extracted) and the system was pressure tested, and apparently it is 100%. It was refilled to the correct level and the temperature coming from the vents compared to air conditioner setting. According to the technician who worked on the car, everything is 100%. I have taken the car back and the service provider told me that the results is as good as one can get from the system and that I cannot compare this car's with another, but they do agree that it do not work effectively. They suggest that I replace all the filters. I checked all the filters, which look good in my opinion, but I tested the air conditioner with all the filters removed, without better results.

Driving home today in 19°C and the air conditioner set to the lowest setting (Lo on screen), it took about 15 minutes before I could feel that the temperature of the air starts to cool down. It is a sunny day with very low humidity, which should not be a problem for an air conditioner. My other car, a black ML270CDi, will blow cold air within 5 minutes after she stands for hours in the sun in summer on a 38°C to 43°C day, which is hot. I can not believe that all is 100% with the car's air conditioner.

I have cleaned the air conditioner's radiator (don't know the correct name) on the outside to make sure it is free from any blockages and that it can operate to its potential.

I am frustrated that the "experts" are not able to sort it out and tell me to accept that the car's air conditioner is not as effective as I would like. Any suggestion will be appreciated.

 

I don't know if it will make a difference, but it is the 4 zone thermotronic system

Thanks

Robert

 

Actually it does

You have a saperate blower in the back which is probably running at lowest setting (fail-safe). Have your blower checked.

For your cooling issues - if refrigerant is not an issue. Here is my experience:

Very Low refrigerant: cold front, hot in back or cold at right side, hot at left or vice verse
Low refrigerant - it will be cool, not ice cold - add coolant
Too much refrigerant - still cool not ice cold because compression cuts-out.

I dont know who filled your gas ut they could have cheated you or over/underfilled/used fake refrigerant.


If I were you, I would pop the hood, push the gas escape valve to remove all R134a. Then take it to MB Dealer for a fill. They cannot charge you cost+half hour labor max. but then you will have a 100% pure 134a Mercedes approved refrigerant.

have the blower checked in back vent.

Finally I have heard aout leaky SAM mixers (that mix hot and cold air). a broken door/va;lve means your correcly working A/C gets hot air mixed in it because mixer is broken. its $40 part and easily replaced under wiper cowl.

https://mbworld.org/forums/e-class-w...rol-valve.html

 

My 2003 W211 started doing this a few weeks ago - reduced cooling on the driver side with better cooling on the passenger side - and now the ac on both sides doesn't cool at all. i'm guessing i should try the refrigerant refill first before attempting to find a leak? the AC has been problem free up till now.