Problem with 211 Luxury Climate Control

[Diapason]

I tend to keep my Luxury Climate Control system on automatic almost all of the time - 20degrees, left and right, back and front.

Having spent a good weekend in Great Langdale in the Lake District we were travelling back to London early today - the roads weren't bad at all and we managed almost a constant 5 hr cruise at 70mph.

All was fine for 4 hours..... and then the temperature in the car started to rise very significantly. Adjusting the temperature had no effect, and neither did setting the fan speed and direction to manual. It was almost as though the blower itself had stopped working. No volume of air (either cold or hot) could be had, and I had to open the windows in order to cool us down.

Having played around with the controls, I set everything back to auto - with the aircon switched off - resigned to the need to book the car into my MB dealer during the week.

And then.... around 15 minutes before reaching home, I noticed that air was starting to come out of the vents again - and then when I switched on the aircon cold air was present within seconds. We shut the windows and all was fine for the rest of the journey.

The car has been maintained fully by MB and given their extra Aircon service once a year, so I am pretty certain that all filters and fluids are in fine condition.

I've tried searching for this problem on this site - and it appears that erratic blower behaviour has been seen on other models, but has anyone else experienced this on the 211?

I'm obviously keen to understand what might have been happening, whether this is something that I can deal with, or whether I do need to take the car to the dealer and - in that case - what insight and additional information I could give them.

Many thanks, in advance, for any advice you can give me.

All the best,
Simon

 

[AndyPCD]

The 211 does suffer with a problem with the heating duo valve playing up and for some reason it always opens up and allows heat in.

I would keep an eye on it as you say its ok now but i would bet it will play up again soon.

 

[ABBY]

hi .if you coud hear the fan blowing but no air coming from vents, most likely your evaporator coil froze up,and not allow air through. By switching system off ice melts and air can blow through again. this fault is normally caused either by a misplaced or faulty sensor
good luck

abby

 

[Diapason]

Evaporator ice-up?

Thanks Abby,

The symptoms do seem to match your description. I could hear the fan - but there was no airflow, and it was some minutes after I switched off the aircon that the flow resumed.

You mentioned a sensor. Is this something that can be changed easily, and is it likely to be something that the dealer would change under goodwill if there's history. Also, more fundamentally, could you tell me what the sensor does? I'm interested to know.

All the best, and thanks for the very helpful advice.

Simon

 

[lynall]

Google frozen evaporator and most links seem to point to low refrigrant pressure, maybe worth getting it checked as even though its had the extra services things still go wrong.



Lynall

 

[Diapason]

Thanks Lynall, I've taken a look. Really useful. The links do indeed mention this as a possibility, and I'll get the pressure checked. To be fair, the links do also mention the 'positive feedback effect' that results from a frozen evaporator and a sensor that detects the coil temperature and stops the compressor if the temperature falls to around 1C. Maybe this is what Abby was referring to? It sounds likely, especially as the airflow on 'auto' had clearly reduced as cabin temperature had stabilised.

Thanks for all your help,

Simon

 

[ABBY]

hi
depending on which ac system there are the following sensors
1.outside air temp mounted next to fog light
2. refrigerant temp sensor/pressure sensor underneath the radiator
3 dew sensor inside the blower unit
4. cabin temp sensor on control unit (looks like a little speaker)next to the digital display
5.cabin temp sensor next to the interior light switch near the rear view mirror

your best bet is to get system diagnosed to prevent you buying a lot of unnecessary parts

cheers

Abby

 

[rlowy]

Hi Simon,

I have the same climate control in my car and very occasionally get a similar problem. It has happened a couple of times.

My "symptom" is that there is no heat, just AC, noticed most of course in the winter.

My solution is to turn the system off by the "0" in the centre of the panel wait a few minuets and turn it on. On most occasions that has cleared it.

When that does not happen I found stopping and completely turning the car off and starting again solved it.

My garage knew of the problem and said it was a sticking value that is worked electronically.

Problem as usual is that it works perfectly when you get to the garage!

Hope this helps

Regards

Richard

 

[ABBY]

hi once again.
re read your posts and came to the strong belief that the problem in your car is blocked active carbon filter. you didn't mention what type of a/c you have 6 or 10 flap motors. if you have the 10 motor system i presume you have a active carbon filter that most probably has never been changed.

cheers
Abby

 

[Diapason]

Air conditioning problem

Abby,

I paid extra for the so-called 'luxury' system - code 581 - with four zones. So I guess that's the 10 motor version?

I had the air-conditioning serviced last September by MB. They charged me £74 + vat and I think they promoted this at the time by saying that this included replacing the carbon filter. However, I've looked over the invoice and the work isn't broken down - so you might well be right.

Everything has worked OK since, but then again I haven't been on another really long journey.

I think I do need to have a chat with the dealer about this, but wanted to go with as much evidence and information as possible - including advice and any experience of similar problems from others.

Thanks for all of your help in this.

Best regards,

Simon

 

[ABBY]

hi
£74 sounds a bit cheap for 2 active carbon filters and 1 pollen filter,compressor oil,gas and labour

cheers

Abby

 

[Diesel Benz]

hi
£74 sounds a bit cheap for 2 active carbon filters and 1 pollen filter,compressor oil,gas and labour

cheers

Abby

I agree, sounds too low to include the active carbon filters.

But do you really have experience about the active carbon filter being blocked? I have not seen it reported on these forums.

Diapason, do you often use the active carbon filter with the manual setting? The active carbon filters only exist on early models with the 4-zone system, have you checked if you really have these filters?

It could be the heat exchanger shutoff motor if heat starts to come once the car has been restarted or AC settings have been adjusted. If it stops blowing, freezing is the likely issues as mentioned earlier in this thread (unless it really is the active carbon filter and the issue is no air flow once the AC is turned to filter air through the active carbon filter).

 

[Diapason]

Many thanks DB.

I must admit, there is a pattern starting to emerge as I read about this topic on other forums too. The following link describes a problem identical to mine, and you'll see that people are replying and confirming the evaporator freeze diagnosis that Abby and you have mentioned.

No air coming from A/C - Benzworld.org - Mercedes-Benz Discussion Forum

Of course, this doesn't mean that it's going to be easy to get fixed, but it does mean that I can be pretty specific when going to the dealer.

Many thanks again,

Simon

 

[christopherwk]

I had to have a new duo valve fitted. I also have the four-zone climate control, and it was only blowing hot air out the vents in the rear.

£30 for the valve.
£500 for labour.
(at main dealer)

 

[Rory]

and given their extra Aircon service once a year,

Sorry, a slight distraction, but do many people do this? I've always thought such extras where little short of a con.

My car is on Mercedes ServicePlus service contract and they certainly won't do it.