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I finally got to my dreaded air recirculation problem.
I have mentioned the problem here:
http://www.slkworld.com/slk-r170-general-discussion/31713-what-does-first-notch-aircon-do.html
And after writing this post and posting pictures of all the stuff I could find (Hope it's useful anyways) I came up with the solution over here:
http://www.slkworld.com/slk-r170-general-discussion/11844-vacuum-leak.html
I took the glovebox apart and took some pictures. The problem that I had is that my "housing door" is stuck on "always fresh air".
On the air conditioning switch there are the following measurements: "0", "." (dot), "1", "2", "3", "4", "5".
"0" - means inside the cabin air only. It is activated by the vacuum Element.
Here's the position of the housing door at "0"

. - means fresh air circulation. It is activated by the spring, while the vacuum is being released from the element.
Here's the position of the housing door at "."

So, my flap was stuck on "." - Only fresh air.

Now, what happens is that there's a part called "Vacuum Element" (part no. 202-800-18-75) is made of rubber and over the time this rubber wears out. It causes a leak, so the vacuum is not created. There's no faulty code since this part is simply a rubber with attached metal piece to it which in its turn attaches to the small manual motor and operates it. Thus opening the "housing door" to allow fresh air or simply closing it - air inside the cabin only.
The part that pumps out the air from the vacuum element is called "Fresh/recirculating air flap switchover valve" (part no. 2028000178). This might generate a faulty code when it's out. But mine was fine. It was just going crazy, clicking all the time due to constantly sucking the air out of the faulty vacuum element.

NOTE: When you turn off the engine, the flap automatically goes into position "0" - fresh air. It is done automatically to release the vacuum and the tension applied to the vacuum element, and also to prolong its life. So my recommendation is to keep your switch in position "0", and don't turn it off all the way to "."(in cabin air only). In order to prolong the life of the element I would recommend to use "." position (in cabin air only) only when you really need it.

The symptoms:
When I was starting the car, turned the switch between these two positions, I heard a click form the "Fresh/recurc air flap switchover valve." Also, when it was in position "." - there was no sound, but in position "0" I heard a hissing sound...
Here's a picture of the "Fresh/recurc air flap switchover valve":

depicted also here:


But the "housing door" didn't open. I saw that the vacuum was there. When playing with the switch I heard a vacuum sound from this "Fresh/recurc air flap switchover valve", the lines were moving, and the "Vacuum Element" (part no. 95 on the diagram below) depicted below was moving too, meaning it was getting the vacuum. But I heard a hissing sound, meaning that the rubber developed a tear somewhere.


The vacuum Element:



From the picture above you may see the "fresh air" position where my housing door is stuck.


In addition, as soon as I started driving the "Fresh/recurc air flap switchover valve" was going nuts...click, click, click, click....
So, I disconnected the hose that connects to the element and closed the opening with my finger and it sucked it =) I mean the switchover valve worked fine: it did what it's supposed to do - sucked the air in/creating vacuum.






Now we need to replace the "Vacuum Element" and I also repaired the "housing door" while in there. It was sooo filthy and the foam rubber it was covered with just deteriorated to nothing due to all the moisture and age. I was planning to replace this stupid door... but the whole process took me forever to disassemble everything and the construction is really stupid over there... Now I understand why repair shop wanted $1200 to replace the housing that costs $40... So, I came up with another solution to fix it =) I think that was a brilliant solution, which WILL save you tons of time and effort while trying to remove the whole heater unit just to get to this stupid door...

Alright, you might not need to remove the whole upper dash like I did since it will give you just a little bit more space to play with. Also, to remove the upper dash you need to remove the upper roof molding (where you reading lights are located), side pillar covers, and driver's dash... way lots of work and it turns out there's a metal frame underneath the dash which makes things even more complicated.
So, I suggest simply removing the glove box, the vacuum tank, and then the air bag.
NOTE: Be careful, since the plastic is really fragile... and old... :(
Disconnect the battery before removing the air bag!!!
To remove the glove box you will need to remove...ah... I didn't count... about 8-10 screws... and it just drops.
Here's what you get:


Now remove the air tank. It's held by 2 screws. Use Philips screwdriver.

The air bag is held by 4 bolts. As far as I remember it's either 12 or 14mm. The connector is on the left side. Since I had my dash apart I just moved the air bag to the side :biglaugh:. But you might want to disconnect the connector. Make sure the battery is disconnected!!! Risk of serious injury!!



Now you have some room to play with the vacuum element. I found it easier to put a small flat head screwdriver behind it and pulling the screwdriver towards yourself to release the clip. Then carefully start turning the vacuum element counter clockwise and it will snap off! Be careful! There's a metal fastener that connects to the housing manual motor. Simply unclip it. Using a flat head screwdriver carefully disconnect the vacuum line plastic connector from the vacuum element! Be careful not to brake it or damage the green hose/line.


Then get you new vacuum element. Another thing that I found to be easier is to pull the metal fastener out of the vacuum element all the way so it extends and carefully snapping it on a small pin located on a manual motor.




Here's a picture of this pin. It's not mine. I took it from Ebay :)
It gives you the idea of where the small pin is and how this stuff works =)

Then position the vacuum element and click it back into place. Reconnect the vacuum line and you're good to go! Reconnect the air bag. Connect the battery and start the car. Let the air fill the air tank and try to play with the switch while watching if the housing door operates correctly.
 

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While I was there I decided to replace the filthy housing door but it turned out to be an impossible mission... But don't worry! I came up with another brilliant solution!
I pulled the housing door back, used paper towel on the bottom and closed it. Then I just simply scraped the leftovers of the foam rubber with my fingers. The paper towel helps prevent all this nasty stuff going inside the blower motor. Be careful not to press too hard since this metal door has circles in it and you don't want to punch through them :). Then I made a solution with rubbing alcohol: 50% water 50% rubbing alcohol. You don't need a lot. I just poured it into one of the empty spray bottles from Windex. The sprayed the terry cloth with it and wipe the housing door. You won't make it smooth but just remove all the tiny bits of foam rubber that may interfere with further process. Let it dry. About 10 minutes. The surface will be sticky from the previous glue! That's what we need too!
Here's how it will look like. Note: I already applied Dynaliner to one side over here:




Next thing I did is I took some Dynaliner material. This material has 3M tape on the back! Really cool stuff! Measured it against my new door. The dimensions are 8.5 x 3.4 inches. Cut it and then cut it in half right in the middle. This will make it easier to glue it.


Then take your time, take one half of your new "precut", position it and simply press it with you fingers. Do the same with the second half. The main thing is to position it neatly! :) One side is done!


Sorry, forgot to take picture of the inner side when it's finished :)

Now the other side.... you'll need some play under the hood...
First trick: Credits go to Bradley - open the hood and use the button on the damper to open it 90 degrees!
Remove 6 screws (as far as I remember these are 20 or 25 hex).

Now remove the windshield wipers. These are held by one (each) nuts. I think using 14mm. Now carefully lift up this plastic cover which covers all the wiper motors. It doesn't go too far but it gives you a little space to work on your housing on the passenger side. You can see below that I already cleaned it =)


Perform the same procedure for the outside part of the housing as for the inner. Don't forget to put paper towel to pick pieces of old foam :biglaugh:. Clean it, measure Dynaliner, cut, cut in half and glue it :tu:. BTW, I pushed the housing back (from the inside of the car) put the handle of a screwdriver to fix it in this position so I could clean the outside part of it.



Assembly is in reverse order.

It's even better now than it was before!!!
That's it! Don't forget to secure your air bag and screw the glove box back in!



Here are some same posts:
http://www.benzworld.org/forums/r170-slk-class/1410439-beeping-please-help-2.html#post3191032
http://www.benzworld.org/forums/r170-slk-class/1410439-beeping-please-help.html#post3177891
 

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Ok, while I have pictures of disassembled dash I'll post them over here :)
Basically I used this guide:
http://www.buellwinkle.com/r170/dash1.htm












The pillar covers are held by two clips. Simply pull carefully. BUT! to remove them you will need to remove sun visors AND two screws located under the upper roof trim. You can access them by removing the clear cover that protects the reading lights. near the rear view mirror.
I forgot about these and simply broke the plastic slips and had to re-glue those:(


 

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I've got this problem going on... Not fun in the winter and the windows are fogging up!

Anyhow, I took the glove box panel off today and checked that there is vacuum, the valve is working, and blowing/sucking on the tube going to the element makes the door open and close.

Problem seems to be that the spring on the door is not working or fell off. So, I disconnected the vacuum lines and plugged the live hose with a screw and left the door in the open position for now.Any idea what the part number is for the door and assembly? The door is in bad shape too and with the dash out I'll just replace the whole unit. Anyone think it'd be prudent to go ahead and replace the element, too?

Thanks in advance!
 

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As I recall, this is the first time I have seen this thread - QUITE IMPRESSIVE Jayson!!! Thank you and I sure hope I never need it. :)
 
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Discussion Starter #7
Problem seems to be that the spring on the door is not working or fell off. So, I disconnected the vacuum lines and plugged the live hose with a screw and left the door in the open position for now.Any idea what the part number is for the door and assembly? The door is in bad shape too and with the dash out I'll just replace the whole unit. Anyone think it'd be prudent to go ahead and replace the element, too?
Davey, while you have everything disassembled, I'd recommend replacing this rubber element. Chances are rubber will fail sooner or later and you will have to dig in back again =( As for the spring, are you sure it's the spring? When you push the door, do you have to apply pressure? It should be like you're trying to push it with a little force to overcome tension from a spring. You can see the position of the door for fresh and in-cabin recirculating air from the picture on top. It's not that easy to remove this whole huge unit... There was a link somewhere in the DIY section to a Youtube video, but it's fast-forwarded and gives you a general idea...
But we ca get you all the part numbers =) They're usually generic but post your VIN to be sure.
As I recall, this is the first time I have seen this thread - QUITE IMPRESSIVE Jayson!!! Thank you and I sure hope I never need it. :)
Thank you Sokoloff! This dreaded flap gave me so much headache... I was so glad I found the problem and fixed it. Hopefully you won't ever have to mess in that area. :wink:
 

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Davey, while you have everything disassembled, I'd recommend replacing this rubber element. Chances are rubber will fail sooner or later and you will have to dig in back again =( As for the spring, are you sure it's the spring? When you push the door, do you have to apply pressure? It should be like you're trying to push it with a little force to overcome tension from a spring. You can see the position of the door for fresh and in-cabin recirculating air from the picture on top. It's not that easy to remove this whole huge unit... There was a link somewhere in the DIY section to a Youtube video, but it's fast-forwarded and gives you a general idea...
But we ca get you all the part numbers =) They're usually generic but post your VIN to be sure.

Thank you Sokoloff! This dreaded flap gave me so much headache... I was so glad I found the problem and fixed it. Hopefully you won't ever have to mess in that area. :wink:
Thanks all for your help. It turns out that the spring had broken. I couldn't see anything before taking out the dashboard, though. I couldn't find a spring at the hardware store that would work so I jammed the gears so the door is stuck on fresh air always and disabled the vacuum system. Shame that it took so much work and didn't result in a 100% fix but I'm happy with it... The only time you really need recirculate is when you're running A/C on a really hot day. But hey, it's a CONVERTIBLE! haha
 

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gipmad,

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Thanks for the write up, Jayson. Do you maybe have your "."'s and "0"'s swapped in this paragraph:

NOTE: When you turn off the engine, the flap automatically goes into position "0" - fresh air. It is done automatically to release the vacuum and the tension applied to the vacuum element, and also to prolong its life. So my recommendation is to keep your switch in position "0", and don't turn it off all the way to "."(in cabin air only). In order to prolong the life of the element I would recommend to use "." position (in cabin air only) only when you really need it.

Just trying to make sure I'm understanding the operations correctly.
 

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Thanks for the write up, Jayson. Do you maybe have your "."'s and "0"'s swapped in this paragraph:

NOTE: When you turn off the engine, the flap automatically goes into position "0" - fresh air. It is done automatically to release the vacuum and the tension applied to the vacuum element, and also to prolong its life. So my recommendation is to keep your switch in position "0", and don't turn it off all the way to "."(in cabin air only). In order to prolong the life of the element I would recommend to use "." position (in cabin air only) only when you really need it.

Just trying to make sure I'm understanding the operations correctly.
Ya, I was thinking exactly the same thing. Almost three year old tread from original post so, a reply probably not coming.
 

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