Hi, I have an issue with my X350 MY 2003:
If I set the climate control to lowest value, I will get 20 k hotter air in the leg room on co drivers side, than outside temperature. The drivers side is approx 10 k lower in temperature than co drivers side.
After inspecting the blend door motors, all work fine, the lower blend door, which enables heat stream through the lower heat exchanger lets still hot air in, even if I have manually pushed it to close (without stepper motor).
So it looks like if the blend door has no foam to close completely. Is this normal, or did the flap / blend door loose the foam over time?

 

Unusual fault; normally it's too cold on one side ! As the heater matrix is always hot, it does seem, as you surmise, the flap that closes off the heater matrix. I would expect these to have a seal on the flap or housing to ensure no escape of hot air. Whether this is foam or not I don't know, but there may be another flap on the path into the matrix that is not closing. However, I'm not an expert, I'm afraid. When I get five minutes, I'll have a look in my X350 Technical Notes.

 

Hi, could you find some useful information?

BR

 

Unfortunately the Technical Notes doesn't have a trouble shooting section, it only describes how things work. The CC unit allows you to set different temperatures left and right. Each output vent to the car has a temperature sensor on it to provide feedback to the Climate Control Module (CCM). Presumably you have the same temperature set for both sides ? You can set the CC to single temperature mode, i.e same temperature both sides. Why not set it to this and see what happens. Other thing I'm thinking of, is you have described the normal problem in reverse, i.e. the usual issue is one side is cooler than the other, which is essentially what you have got. The cause of this is normally the heater matrix being blocked. What temperature do you have to have on the display to get a reasonable temperature on the colder side ?

 

Hi, Im driving the main time without air conditioning. I have the same temperature setting both sides, but leg room air is much hotter on the co driver side, than on the left side, approx. 20k.
even if I use the air conditioning, the air is too hot in the co drivers leg room.

Is there a second blend door, which switches of the air to the heater matrix?
Could you please provide me the description how it should work?

BR

 

You really need to get the car's fault codes read (use the search facility and search on 'fault', 'code' and 'scanner' for advice on that). The workshop manual lists a number of possible fault codes for the air conditioning (the ones that might apply to you seem to begin B28..)

You can find a link to a download of the workshop manual in one of the 'Sticky' threads at the top of this subforum.

 

There is no fault code stored in the car about climate control. The heat blend door is closed but still a bit of hot air comes through it and is mixed with the cold air.

 

Well, I think it's time for a visit to a workshop, as my technical knowledge, (such as it is - not very much !), is now exhausted, and I suspect not many folks on here are experts in the CC system.

BTW, you should not run it without the air con component operating. The whole system and its software is designed to work with both in operation summer and winter.

 

Hi Mitchell, thanks for your support! Last night I have downloaded some files and I hope to find some answers in them.
In my opinion, there can be only two things:

1st: The foam to close the blend door totally is missing
2nd: Another blend door before the heater matrix is not working properly.

Do you know if there is another blend door before?

 

Hi, attached is the air distribution box. RH temperature blend servo motor, this one opens and closes the blend door, which is not 100 percent closing.
I have to think about, if cool air bypass has also to do something about it.
So the foam guess is the most suitable and most costy reason I suspect.

 

That drawing is in my technical notes. It is possible to set the system so that only a single temperature is set that applies to both sides. What happens if you do this ?

 

AFIK there is no other blend door.
It seems to me that you have identified the likely problem yourself.
There was a post on here some time ago and the root cause of the problem was
that some foam had fallen off and was blocking a vent,/duct .
I have never seen an image of the cc internals on the internet.

 

Not really relevant to the matter at hand, but I've just noticed ... while the air intake and pollen filter are on the left hand side of the car (well it is on mine) in the diagram above they're shown on the right hand end of the unit.

So it looks to me as if the diagram has been 'flopped' (reversed left-to-right) somewhere along the line.

 

I guess you are from UK, I'm from Germany so the steering wheel is on left side.

 

The unit is made so that the fan module can be on either side, it being attached separately to the main CC box.

 

Does anybody have an idea how to access the blend door inside to re glue the missing foam? Through the duct of the floor vents will not fit I think.

 

I think that you must be looking at removing the whole box and even then you will need to
break open the box.
It's possible that the fault is one of the temp sensors shown on top of the box?
A long shot but have you scanned for codes?
My son has an old Passat and we knew there was a problem with the blend doors
because you could hear noises under the dash.
When he scanned the vehicle it came up with a DTC for a blend door motor.

 

Hi, all blend door motors are working, there is no dtc stored. No one is blocked. I could move the heat door manually and in closed position it felt like plastic against plastic hard closing and not soft closing as it would do with foam on the door or housing.
Up to now, I could not manage to take a look about a measurement value in the RCCM, is there a hidden menu?
I will go for it the next days, tranny overhauling (Sonnax zip kit), cooling leakage and airbag are before in my list and p0420. So quite a lot to do or we could call it a Bastelburg

Thanks for your support!