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My C280 seems to have developed a bad actuator motor MB calls it a stepper motor in the plumbing vent work. All air blows from defrost and side vents. I am aware that there my be 3 motors.
Question is where does one start to disassemble the dash. I looked at my wis cd with no luck because mercedes uses different terms and IS DIFFICULT TO FIND. Unless someone can send me a link that would be appreciated.

Phil
 

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1995 C220 102k
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Check this out - complete tutorial...and dont worry, I am currently living in Mercedes Vacuum Hell too!

With this post
 

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1999 C43 AMG, 1998 C43 AMG
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hoo boy. where do I begin.

the system that controls the vent selection is almost entirely vacuum controlled, as you appear to already know. there's a vacuum valve block under the hood. it takes the master vacuum line (from engine vac pump) and from the aux vac pump (in trunk).

that vacuum block sends the vac supply off to different areas: door lock system and vent system. one of these lines runs to another vacuum valve block, only this one is far more complex. it's electronically controlled from the climate control unit. it sends vac lines running all over the place under the dash to various vacuum elements/bellows. these vacuum elements are little boxes with rubber balloons inside. vacuum will suction these balloons so they collapse. attached at the end of each balloon is a metal rod that is attached to the vent. if vacuum is taken away, balloon naturally expands back the way it was and opens/closes the vent. these vacuum elements/bellows often fail.

you press a vent selector on the climate control unit, it sends a signal to the 2nd vacuum block which changes the vacuum supply to the proper bellows in the dash to get the desired vent selection.

the block under the hood often fails. it cracks at the part with a chrome ball bearing. listen for it hissing. turn the key on (not engine) and roll windows down. press buttons on climate unit to make it change vent selection. stand out beside the block under the hood and listen for hissing sounds. if you hear hissing, you have an issue there. the block is like $30 to replace.

most common its the bellows in the dash, though. requires removal of the dash.

I spent 2 days removing and replacing my dash. I had to replace the bellows that controls teh center vent, as well as the ac evaporator and expansion valve. I think I died during that job, and I am sending this from heaven (or hell?)

however, if nothing changes when you press any buttons, I would bet you've got other issues. check the vac block under the hood. teh 2nd one is in the dash under the glove box. easily accessible when you drop the panel in the top of the passenger side footwell. listen for hissing sounds at that block.
 

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1995 C220 102k
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cheap fix for now... remove the under dash on the passenger side - you will see two bellows in the console, pull the one closest to the firewall toward the passenger side, then pull down, this will manually open the dash vents. disconnect the vacuum line from the bellow and cap it.

this will give you dash AC until you remove the dash.

SULACO - You dont by chance have the part numbers for the two bellows you had to replace do you?
 

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cheap fix for now... remove the under dash on the passenger side - you will see two bellows in the console, pull the one closest to the firewall toward the passenger side, then pull down, this will manually open the dash vents. disconnect the vacuum line from the bellow and cap it.

this will give you dash AC until you remove the dash.

SULACO - You dont by chance have the part numbers for the two bellows you had to replace do you?
doin12volt: i tried this today and found that it causes air to come out of only one side of the center vents? also why do you say to cap it? whether the line is connected or not and whether it is capped or not seems to make no difference in my car, the bellow just needs to be pulled down and left there in order to get any air flow through the center vents.
 

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1997 C230
My vents weren't working, nor could be selected, so I opened dash under glove box and found a plug disconnected from socket, just hanging. I plugged it in and now my climate control works perfect. And another thing, the cabin temperature sensor for climate control is located in the cabin light, on roof, my started to make irritating noise from age, so I took that appart, there is a motor (fan, it's tiny) I removed it, and assembled sensor back, it works without that fan, it just reacts to changes in temperature quicker.
To me it's not a problem.
 

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1995 C280 SOLD
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vent fix

I just repaired my center vent problem this weekend and what a PITA it was. Zade Faraj's link With this post helped me start off. I didn't have to take off the dashboard, just removed the glove box & cover under the passenger airbag (where you access the air filter). You need a lot of patience and thin hands (they will get scraped) to do this because there is no space to move around. Some special long handle tools that can grab would help also. Make sure your vacuum distributor block in the engine compartment is not leaking.
I tested all my vents when I removed the covers, it took some trial and error and moving vacuum hoses that worked to test several different bellows. Just be careful not to overheat your vacuum pump, it shuts off after like 30 pulses, I've done 3-4 cycles (30 pulses each) in a row with no problems, vacuum pump just feels warm. You don't need the car engine running, I had a battery charger hooked up to my batt.
I found that (2) of my bellows where not working right and bingo it was the one for the center vent. The second bad one was for the refresh/recirc bellow (this one had 2 bellows built into one). When I took them apart (be careful of the tabs) I found little tears in the rubber, I just used industrial strength super glue and tested it after, the rubber is easy to tear & don't know why Mercedes used them. It was easy to remove the metal arms connected to the vent flaps, just have to pull/push the metal arm away from the flap (the metal arm has a hole where the plastic tab fits to lock it loosely). Ensure hoses are disconnected, then after you disconnect the arm just slide the plastic bellow housing off its plastic support and pull out of the dashboard. It takes some twisting and guidance through other hoses and wires in the dash. Putting them back into the dash is a major PITA. You have to reach in and with your hand at odd angles you have to feel your way to put the metal arm back onto the plastic tab for the vent flap. The center vent bellow has a metal support and I had to bend it a little to put the bellow back onto it.
Warning: this was my first time and like I said you really need thin fingers to attempt this, I almost got frustrated enough to rip the dashboard off and declare victory!! :D
When you place the Climate into AUTO it opens the center flap and a refresh/recirc flap, but the refresh/recirc flap closes after a min, that's why you get air through the center vent for a min while you center flap is stuck closed. During my initial testing earlier I noticed the Climate control system goes through a whole complicated ballet of orchestrated moves, specially in AUTO. My climate control works good for now, hooray.
All in all, I didn't need to remove the dashboard, hope the glued bellows last another decade, & have somewhat understanding of the system. I did it this way because I didn't want to remove the steering wheel, dash, wood trim and I love scrapped knuckles (masochist?)...but during the process I sometimes wished i did remove the dashboard.

Side note: also check your software version for your climate control, there were problems with the old software causing the center vent problems also.

Question: I bought this used, but if anyone has an original owned C280, do the side vents always blow air?

GL and hope this helps :thumbsup:
 

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1995 C220
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I have a 95 c220. I'll have to check; if I remember right, the sides do always blow, I always assumed it was to keep the side windows clear.
 

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side vents do blow all the time

I have a 95 c220. I'll have to check; if I remember right, the sides do always blow, I always assumed it was to keep the side windows clear.
Thanks. I just looked at my driver's manual (it is actually informative, wow!) and yes the side vents always blow air at every setting, except for "Off." ;)
 

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1995 c220, where is the vacuum valve block under the hood? and I understand there is another block under the dash. where is it and how do I get to it?
 

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1997 C230
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cheap fix for now... remove the under dash on the passenger side - you will see two bellows in the console, pull the one closest to the firewall toward the passenger side, then pull down, this will manually open the dash vents. disconnect the vacuum line from the bellow and cap it.

this will give you dash AC until you remove the dash.

SULACO - You dont by chance have the part numbers for the two bellows you had to replace do you?
I need help w this. Have a 97 c230. I can't figure out what to pull/remove to direct air to center vents. Only comes out side and defrost. 288k miles...not spending the money to fix properly! Please I can't stop sweating!
 

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1999 C43 AMG, 1998 C43 AMG
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I need help w this. Have a 97 c230. I can't figure out what to pull/remove to direct air to center vents. Only comes out side and defrost. 288k miles...not spending the money to fix properly! Please I can't stop sweating!
It's been 3-4 years since I did this job, but if I recall correctly the metal bar that controls center vents is on the drivers side in the US model. Disassemble knee bolster and remove. Wiggle yourself up in there in an upside down position with a bright, tiny flashlight and something long you can push/pull things with. There will be an aluminum-looking metal bar going straight up and down on the side of the black plastic guts of the system. to be clear, there's a giant plastic black box inside your dash that houses your fan, evaporator, and heater core. the metal bar is mounted to the side of that with the bellows on the bottom. See if you can just shove the bar up and disconnect it from the bellows (or the bellows will pull it back down).

No point trying to go in from the vents. My W124 I can use a long long screwdriver and force the flap open. The flap in the w202 is burried way far back inside and down, making it impossible to see/adjust through vent.
 

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It's been 3-4 years since I did this job, but if I recall correctly the metal bar that controls center vents is on the drivers side in the US model. Disassemble knee bolster and remove. Wiggle yourself up in there in an upside down position with a bright, tiny flashlight and something long you can push/pull things with. There will be an aluminum-looking metal bar going straight up and down on the side of the black plastic guts of the system. to be clear, there's a giant plastic black box inside your dash that houses your fan, evaporator, and heater core. the metal bar is mounted to the side of that with the bellows on the bottom. See if you can just shove the bar up and disconnect it from the bellows (or the bellows will pull it back down).

No point trying to go in from the vents. My W124 I can use a long long screwdriver and force the flap open. The flap in the w202 is burried way far back inside and down, making it impossible to see/adjust through vent.
you just saved me. holy crap that is awesome! i wasn't sure what the bellow was...but i was able to see the metal bar you were talking about going to the round grey plastic thing (the bellow i'm assuming). i couldn't get a screwdriver that i had in far enough, but i slip the bellow towards the passenger down and then pulled it down...that pulled on the metal bar and now air is coming out of my center vents. i can't thank you enough.

now...if i have to go turn defrost on and heat i'm assuming i'm going to have to push it back it?
 

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now...if i have to go turn defrost on and heat i'm assuming i'm going to have to push it back it?
not a problem. I'm probably the world's biggest w202 fan. Drove a 1994 C280 for 13 years and miss it till this day (and now I have a C43 AMG!)

but to answer follow up: depends on the health of the bellows controlling it. if it did not naturally pull itself back down after you moved it, then the bellows likely failed in both directions. normally they fail in one direction (it will open but not close, or vice versa). Sounds like your bellows is totally kaput! I would bet that it won't move if you use heat or defrost.
 

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not a problem. I'm probably the world's biggest w202 fan. Drove a 1994 C280 for 13 years and miss it till this day (and now I have a C43 AMG!)

but to answer follow up: depends on the health of the bellows controlling it. if it did not naturally pull itself back down after you moved it, then the bellows likely failed in both directions. normally they fail in one direction (it will open but not close, or vice versa). Sounds like your bellows is totally kaput! I would bet that it won't move if you use heat or defrost.
Yup won't change if I move to defrost. Manual control is good by me. Can that be easily replaced from under the dash?
 

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Yup won't change if I move to defrost. Manual control is good by me. Can that be easily replaced from under the dash?
If you feel you can access the bellows connected to that metal bar using the same method you just went through, then yes.

I had 3 bellows fail behind my dash, plus a blown evaporator. I spent 2 weekends pulling the dash and doing it myself.

Not for the faint of heart. There's a reason shops charge $2,000-$3,000 for that job.
 

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Looking for parts list

hoo boy. where do I begin.

the system that controls the vent selection is almost entirely vacuum controlled, as you appear to already know. there's a vacuum valve block under the hood. it takes the master vacuum line (from engine vac pump) and from the aux vac pump (in trunk).

that vacuum block sends the vac supply off to different areas: door lock system and vent system. one of these lines runs to another vacuum valve block, only this one is far more complex. it's electronically controlled from the climate control unit. it sends vac lines running all over the place under the dash to various vacuum elements/bellows. these vacuum elements are little boxes with rubber balloons inside. vacuum will suction these balloons so they collapse. attached at the end of each balloon is a metal rod that is attached to the vent. if vacuum is taken away, balloon naturally expands back the way it was and opens/closes the vent. these vacuum elements/bellows often fail.

you press a vent selector on the climate control unit, it sends a signal to the 2nd vacuum block which changes the vacuum supply to the proper bellows in the dash to get the desired vent selection.

the block under the hood often fails. it cracks at the part with a chrome ball bearing. listen for it hissing. turn the key on (not engine) and roll windows down. press buttons on climate unit to make it change vent selection. stand out beside the block under the hood and listen for hissing sounds. if you hear hissing, you have an issue there. the block is like $30 to replace.

most common its the bellows in the dash, though. requires removal of the dash.

I spent 2 days removing and replacing my dash. I had to replace the bellows that controls teh center vent, as well as the ac evaporator and expansion valve. I think I died during that job, and I am sending this from heaven (or hell?)

however, if nothing changes when you press any buttons, I would bet you've got other issues. check the vac block under the hood. teh 2nd one is in the dash under the glove box. easily accessible when you drop the panel in the top of the passenger side footwell. listen for hissing sounds at that block.
Greetings drivers. I am planning to tackle this Vacuum element job myself shortly and want to buy the parts in advance. I need descriptions/ part numbers for the manifold under the hood, and the center vent element and the re-circ element. Any diagrams / pictures and a source of the same would be greatly appreciated.
Thanks in advance for helping.. Marty
 

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I need help

I have a 1995 C220 and I too am having issues with my climate control. From the research i did I believe I have it narrowed to a vacuum/bellows or the stepper motor..

Here's the scoop.....I bought the car used 2 years ago and at that time the blower fan wasn't working. Simple fix at that time I replaced the resistor and all normal operations were fine. At times whenever any climate control was turned on you would hear a flap open or close loudly. Now more recently the blower fan quit working again. So I assumed the resistor again so I replaced. ....not the issue. So I get into the diagnostics and all of the codes I am getting deal valves and flap positions. And when I turn unit on and try to switch flow position I hear nothing getting no hot or cold air anywhere. Fan is still not working. Please any and all advice is greatly appreciated.
 
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