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Thread: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

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    HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    MODERATOR'S NOTE: For an update on vacuum pod availability from MB and aftermarket sources, and pricing, please check this thread.


    BACKGROUND

    When I purchased my 560SEC 11 years ago, I lived in Portland, Oregon. Just prior to purchase of the car, it had been converted from its factory-issue R12-based ACC system, to R-134a. However it was a "straight" conversion, which didn't replace any of the critical components such as the compressor, condenser, receiver/dryer, nor expansion valve. The system was basically flushed, new fittings were installed, and the system was converted over to the supposedly more "enviro-friendly" R-134a refrigerant.

    In Portland, OR, where the summer climate is generally quite mild, there is no need for regular / consistent use of the air-conditioning system except for the height of summer, and even then perhaps only for a couple of weeks. The R-134a system was OK in this usage; although it was never super-cool, it was adequate for the limited usage I gave it.

    After I moved to Houston, TX in 2008, I quickly found that the R-134a system was inadequate for spring/summer/fall usage. Basically, A/C must be used in Houston around 9-10 months of the year when driving automobiles. It is particularly required during the May-October months. After suffering for the summers of 2009, 2010, 2011 and most of 2012 with the R-134a based system, I finally had enough and decided to convert it back to R-12. It helps that the cost of R-12 has come down dramatically from what it was 10-15 years ago, and there is plenty of it available when needed. In the meantime, the price of R-134a has actually gone up quite dramatically.

    So, in September of 2012, I had my mechanic shop re-convert my ACC system back to R-12. At this time, they installed a brand-new compressor, receiver/dryer and expansion valve, and introduced R-12 fittings back onto the system. After this conversion, the system blew extremely cold air, which was welcome. However, during this September/October time frame, the summer heat was winding down so I had little to no chance to really test the system adequately.

    Finally, the summer of 2013 rolled around, and the heat (as usual) got intense starting in late May. I was using ACC every day and it worked quite well. However, I had a problem during June and into July whereby the system would begin to blow increasingly warm air, particularly when running at stoplights and in traffic jams. I performed multiple tests and determined (using a spare Klima relay) that the A/C system was working fine. The compressor was firing when it should have; it was condensing water underneath the car, and the fittings underhood were sweating ... all this meant the system was working adequately.

    Some additional tests of the system function showed that the "fresh air" flap, located behind the passenger-side airbag, was open all of the time and not closing when the A/C system was running. This meant that the system was pulling in hot outside air and mixing it with properly refrigerated air, making for a warm to mildly cool system -- particularly when the car was not moving.

    Further investigation confirmed this -- there is a simple test to check the fresh air flap position / operation. With the engine running and the ACC system operating, you put your hand on the plastic air intake grill at the base of the windshield (hood open). If you can feel air movement at this grill when the A/C system is running, then you know that the flap is wide open and admitting warm air. A check with my 560SEL, which has a properly operating ACC system, confirmed this condition. This fresh air flap is controlled by a PAIR of vacuum pods, both with dual chambers, because a significant amount of force is required to move and control the rather large fresh-air flap.

    Thus, the remedy for this was simple: replace the inoperative pair of vacuum pods that controlled the fresh air flap. Although these pods are fairly easily accessible by removing the passenger-side airbag, the more I thought about it the more I edged toward replacing all six pods in the system. As far as I could tell, with my records of the car, none of the other pods had been replaced save for one I had done in Portland by my mechanic there. So it was a relatively simple matter to just look up the part numbers for the pods and order them.

    I checked the prices of the pods carefully. Four of the six are Behr pods (OEM) and are available for somewhat cheaper than factory pods, through AutohausAZ.com. Two of the pods are available for less money through parts.com. So, I ordered all six of the pods from their respective sources and vowed to do the job when the right time came.

    PARTS
    • Fresh air pod #1 (short/gold arm): 000 800 57 75
    • Fresh air pod #2 (long/silver arm): 000 800 58 75
    • Defrost vacuum pod: 000 800 43 75
    • Center nozzle vacuum pod: 000 800 67 75
    • Leg room flaps vacuum pod: 126 800 14 75
    • Scoop air flap vacuum pod: 000 800 40 75



    TOOLS NEEDED
    • Medium-sized Philips screwdriver
    • Flat-blade screwdriver
    • Long or bent needlenose pliers
    • 10mm and 13mm sockets, 1/4" ratchet with 6-12" extension
    • handheld flashlight
    • Mityvac or other vacuum tester (not required but helpful)
    • 5.5mm 1/4" socket
    • "stubby" Philips screwdriver
    • cutter pliers



    PART 1: Fresh Air Vacuum Pod Replacement

    The first step is to put the passenger and driver's side seats back all the way in the their tracks, using the door seat-bottom switches. This will give you the maximum amount of room for working under the dashboard, which you will be doing on both sides of the car.

    Next up is to disconnect the battery. This requires a 13mm open-end or box-end wrench on the negative battery terminal. Once loose, I just wrap it in several folds of a rag and set it on the battery so it doesn't make contact with the negative battery pole.
    IMG_2831.JPG IMG_2832.JPG


    The next thing is to disconnect the airbag module, AFTER you have disconnected the battery. Remove the passenger side carpets, and use a 10mm socket on an extension to remove the nut that holds the passenger kickplate in place. Under the kick-plate you will find a number of connectors, including those for the factory alarm, the airbag connector (red colored), and the O2 sensor at the lower left near the edge of the carpeting. Notice that I disconnected the factory alarm (last photo below) many moons ago....
    IMG_2833.JPG IMG_2834.JPG IMG_2835.JPG IMG_2836.JPG


    Find the red airbag connector, and disconnect it. It pulls straight off.
    IMG_2837.JPG IMG_2838.JPG


    Next up, you'll need to remove the passenger-side airbag. As with the 500E/E500, it is held by a 10mm long bolt that is oriented vertically and accessed through a hole underneath the dashboard. Your 10mm socket + extension used to remove the passenger kickplate is re-used to access this long bolt. Remove it. See how long it is?
    IMG_2839.jpg IMG_2840.jpg


    Then, you can slowly work out the passenger-side airbag module using a CAREFUL back-and-forth motion. Unplug the two red plugs that are in the back of the two sides of the airbag, on the back of the module. Tuck the forked airbag power cable into the dash, below where the airbag sits, to get it out of the way.
    IMG_2841.JPG IMG_2842.jpg IMG_2843.JPG IMG_2844.jpg


    Here are a few reference shots of the airbag frame, which will come in handy when it comes time to reassemble the airbag and put it back into the dash.
    IMG_2845.JPG IMG_2846.JPG IMG_2847.JPG


    Although you don't need to do this for removing the two fresh-air flap pods, I opted to begin to remove the airbag frame as I am replacing all six pods and need the maximum amount of room to work. I also removed the under-dash tray at this time, as well. It is held by the three screws you see in the last photo above (located behind a trip strip) and two plastic "holder" screws below the dash near the hole to access the airbag long-bolt.
    IMG_2848.JPG


    Next, I removed the plastic flexible tube that supplies air to the right-hand dashboard vent. This just snaps off at both ends (press-fit) and pulls out easily.
    IMG_2849.JPG IMG_2850.JPG


    Now that you have some working room, you can lift up the fabric cover and expose the two pods that control the fresh air flap. As you can see, they operate the flap control lever in a "push-pull" arrangement to maximize leverage for this very large flap (which is visible in the background of both photos below, with the red number written on it).
    IMG_2851.JPG IMG_2852.JPG


    To remove the pods, you need to pull off the two rubber vacuum elbow connectors on the pod's vacuum nipples. The green vacuum line goes on the top of the pod, with the red line on the lower connection. As you can see, the pods on the later (post-1985) W/C126 models use a "bayonet" mount, by which plastic tangs at the base of the pod are inserted into slots, and the pod is rotated about 15 degrees to "lock" it into the mounting base. You can see these tangs in both of the photos above, locked into the base. The lever also has to be disconnected from the flap control lever. This can be done with a pair of needle-nose pliers to GENTLY compress the end of the plastic ferrule, while using your fingers to LIFT the pod's lever clear of the ferrule. It's self-evident when you see how it works. The main thing is NOT to break the ferrule as it is old plastic, and very likely quite brittle.

    Here are a couple of photos of me lifting the pods clear of the dashboard.
    IMG_2853.JPG IMG_2854.JPG


    Here are the two fresh-air flap control pods, as removed:
    IMG_2855.JPG


    And here are the old pods (light pink bodies), next to their Behr replacements (darker pink bodies):
    IMG_2856.JPG IMG_2857.JPG IMG_2858.JPG


    As you can see, the "factory" MB pod (see the last photo above, bottom (darker) pod with the multicolored label) is indeed made by Behr despite no outward indication on the MB labeling/packaging.
    IMG_2861.JPG


    The manufacture dates on the pods that I pulled from the car were 89/20 and 89/30, respectively (May, 1989 and August, 1989) so they were the original pods. Not bad ... they lasted nearly 25 years !!!

    Some additional checking showed that the short/gold pod (on the right side of the push-pull arrangement) was the bad one -- the upper chamber was not holding vacuum, indicating that the rubber diaphragm inside had developed a tear or hold that did not allow it to seal.

    I will continue this series on pod replacement with Part 2 in the near future.

    Hope you enjoy this and find it useful.

    Cheers,
    Gerry

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Good post, Gerry. Is the W124 a/c system set up to use similar vacuum pods and flaps?
    Jon D.
    1994 E420
    1995 E420

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Yes, in general the pod replacement on the W/C126 is similar to that on the 124. However, on the W124 the top defrost pod requires removal of the dashboard to access. In addition, on the W124 one of the pods is located INSIDE of the plastic heater box.

    On the 126 all pods can be reached without removing the dashboard and all are reasonably accessible. You just have to disassemble the center column, console, passenger airbag/glove box area and remove the side carpeting pieces on both sides of the console.

    The work to replace both fresh air flap pods as documented above required approximately 1 hour 10 minutes, including time to take photos and lubricate the flap control lever with a dab of silicone lube.

    Here's a link to my HOW-TO on pod replacement for the W124: https://www.500eboard.com/forums/show...AC-vacuum-pods

    Cheers,
    Gerry

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Minor clarification:

    On the W124, you can replace the footwell pod(s), and the defroster pod, without pulling the dash.

    The center vent pod (located inside the heater box), diverter pod (located on top of the heater box), and the two main air flap (aka "recirculation") pods against the firewall all require dash removal. If you pull the dash... replace ALL the pods with new ones.

    Dave M.
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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods



    UPDATE: Right now I've got 5 out of the 6 pods out of the car, with three of the 5 pods replaced. The remaining two should be fairly easy.

    The last pod is accessed in the driver's footwell, next to the expansion valve behind the side console carpet. This is probably the easiest pod to replace. Saving the easiest to last.

    I'm cleaning everything up as I go, lubricating and taking my time. So things progress fairly slowly as I take my time to document along the way.

    Right now I'm going to take a break to grab a late lunch before I get back to work. I think I can get things wrapped up tonight pretty easily.

    The defroster and center flap pods are by far the worst in terms of accessibility, but overall this job on a 126 is far easier than on the 124, if even because one doesn't have to remove the dashboard. and nearly as much of the entire front fascia/instruments/switches/etc.

    Lots more pod replacement photos and commentary to come....

    Cheers,
    Gerry

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Thanks for the link, Gerry. Almost every time I hear that flap noise on startup I think about how difficult it would be to fix something in there. But it doesn't look to be anywhere as bad as replacing the evaporator core.
    Jon D.
    1994 E420
    1995 E420

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    If you need to replace your evaporator, you've done about 3/4 of the work required by doing the pods. Ergo, if you ever do an evap, do all pods at the same time. It's incremental labor for the most part.

    I'm waiting for a HOW-TO on replacing an evap from GSXR.....

    5 of the 6 pods are now installed and tested, all good. ACC PBU is installed, and the console is coming together now. After that I will re-install the passenger airbag and then tackle the last pod at the driver's side near the gas pedal. Have to remove that piece of console side carpet to access it. So, about 80% done with the job.

    Did a few other incremental tasks as well ... lubricated the moving linkages for the leg room flap and the fresh air flap with a dollop of gleitpaste on the gear teeth of the linkages. Also, I replaced the ratty-looking adhesive strip on the temp wheel (that has the temp numbers in blue, white and red zones) with one of a few spares that I had on hand. I had ordered new Centigrade (Celsius) strips last year for just this occasion. The previous owner of my SEC was a top executive at Sun Microsystems in Silicon Valley, a Dutch guy. He had a shop convert the Fahrenheit trip strip to centigrade, and it had always looked a bit worn and ratty. So while the PBU was out of the car, I partially disassembled it and replaced the adhesive temp indicator strip. About 20 minutes worth of incremental work.

    A couple of other minor repairs included using electrical tape to repair a fraying black fabric tape around a wiring bundle, so that it wouldn't unravel any more. Also reconnected a couple of the optical light connectors at the backs of a couple of dashboard switches, which weren't illuminating when the car's lights were on at night. Also replaced the 2W bulb at the "spider" ... the optical connector that provides illumination light to the switches in the PBU for the rear dome light switch, ACC recirc switch, antenna up/down switch and the rear window defrost switch. It's sort of a clever arrangement ... I took a couple of photos of the spider so y'all can see how it works. Some real Benz ingenuity from the 1970s.....

    Parts 2 and 3 coming soon....with lots of photos. Charging up my camera battery. I was lucky today; the weather only got up to 90F, rather than the normal 94-97F. That difference in temp actually made it (almost) bearable to work out in the garage, though I did have to come in once an hour or so to cool off....

    Cheers,
    Gerry

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Good work Gerry .. Don't know how you do it in that Houston heat....we've had a heat wave of our own the last week or so up here in the NE, my garage is like an oven, I can't take more than 1/2 hour or so before I am drenched, and that's just doing some light detailing work....can't imagine what it would be like taking apart my dash!
    Andy
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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Quote Originally Posted by gerryvz View Post
    I'm waiting for a HOW-TO on replacing an evap from GSXR.....
    I genuinely hope that I never, EVER, am able to document an evaporator replacement. I'd rather have multiple root canals without anaesthetic.

    *shudder*


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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Damn, we were all looking forward to that!

    Jon D.
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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    PART 2: Center Console Vacuum Pod Replacements
    Includes: Defroster, Hot Air Flap and Legroom Flap Pods

    Three pods reside within the confines of the center console of the W126: the defroster control pod, the hot air flap pod and the legroom flap pod. Although tight (particularly the dual-chamber defroster pod), all three pods can be changed without removing the dashboard from the car. The legroom pod (the lowest one of the three) is by far the easiest pod to change. Like the mid and later W124s, the legroom pod is of a flattened, rectangular design rather than the pink and black legroom pods used in the very earliest W124 and Generation 1 W126 models.

    This provides a tutorial on how to replace these three pods. When complete, you will have replaced five of the six pods in the car. The remaining pod requires the driver's side under-dash panel and console side-carpeting be removed. It is above the gas pedal.

    So, let's get into the replacement of the center-console pods....

    The first step is to remove the center console wood, the coin tray/switch panel, and the ACC PBU assemblies.
    IMG_2862.JPG IMG_2863.JPG IMG_2864.jpg IMG_2865.JPG IMG_2866.JPG IMG_2867.jpg IMG_2868.JPG IMG_2869.jpg


    With everything removed, two of the three vacuum pods in the center console begin to reveal themselves...
    IMG_2870.jpg


    First is the leg room flap pod.
    IMG_2871.JPG


    Then you see the hot air flap control pod, just above and to the right of the leg room flap pod.
    IMG_2872.jpg


    Also making its appearance is the fiber-optic "spider" assembly, which distributes light from a 2W "peanut" bulb to illuminate five different switches in the dash area.
    IMG_2873.JPG


    And lastly, above and even more to the right of the hot air flap pod, is the defroster pod, which is a larger, dual-chamber pod. The two vacuum lines that feed this pod are apparent in the lower part of the photo.
    IMG_2874.jpg


    The first step in attacking the center console pods is to remove the plastic "guard" that covers the legroom flap control linkage, where it attaches to the black rectangular vacuum pod. This guard just presses into the heater box with three prongs molded into it, and pulls straight off and out.
    IMG_2875.JPG IMG_2876.JPG


    Removing the guard gives you a much better view of the linkage itself. The pod's arm is secured to the linkage via a press-on grommet and a rubber washer to reduce friction. This can be pried off with the end of a flat-blade screwdriver. I placed a white rag underneath this area to catch this (and other) hardware in case it suddenly popped off. It would be nearly impossible to retrieve any lost hardware in the depths of the center console, so some precautions taken early on are a very good thing. And in fact, this rag saved me heartburn at least two different times during this replacement job.
    IMG_2877.JPG IMG_2878.JPG IMG_2879.jpg IMG_2880.JPG



    After disconnecting the vacuum line, the leg room flap vacuum pod then just pulls straight out off of its two metal mounts. Takes just a few seconds to remove it.
    IMG_2881.JPG


    Next up is the hot air flap control pod, which is immediately up and to the right of the leg room flap control pod you just removed. Some say this is the most difficult pod to replace, for reasons that will be revealed in just a minute. This pod is pressed into a plastic housing with three prongs, and this housing is attached to the heater box by four sheet metal screws. These screws utilize a 5.5mm (not 5mm, and not 6mm) head, so you MUST have a 5.5mm 1/4" socket on hand to remove them. Use your ratchet and a long extension to get to all four bolts. A "wobbly" extension is helpful for the uppermost right one.
    IMG_2883.jpg IMG_2882.JPG


    Another thing you can do to make this housing removal easier (and also to facilitate removal and replacement of the defrost pod, which is next on the list) is to remove the right-hand center vent. This pries out with a clip at each end, which is pried inward with a flat-blade screwdriver. Once both clips are pried inward, the vent grill pulls straight out. It helps removal if you rotate it downward a bit. Behind the grill you will see a thick rubber diaphragm, which is an air guide from the plastic tube into the center vents.
    IMG_2884.JPG IMG_2887.JPG


    You will want to unclip this diaphragm at the two points it is clipped to the center vent frame (it easily unclips) and then move it off to the left side of the vent. This will make much more room available for your fingers to remove the next two pods.
    IMG_2888.JPG


    After you have the rubber diaphragm taken care of, you need to turn your attention back to the hot air flap control pod. You should have already removed all four of the 5.5mm screws that held its housing to the heater box. It will be hanging by its control arm to the heater box flap, through a hole in the outside of the heater box. Notice how the end of the control arm is bent at a 90-degree angle, and is pressed into a white plastic ferrule that is pressed into the hot air flap itself. I took a close-up photo of this below. You can also see all of these pieces after they are removed from the car. The light-brown gasket is a rubber gasket that fits between the pod's housing and the heater box to provide a seal and insulation. You can also see how the ferrule fits onto the end of the pod's control arm.
    IMG_2890.JPG IMG_2891.JPG IMG_2893.JPG


    As I mentioned, the pod is held onto its housing via three prongs, secured by grommets. Take a pair of cutter pliers and snip off the ends of the prongs (above the grommets) -- this will make the removal of the grommets far easier with a flat-blade screwdriver.
    IMG_2894.JPG IMG_2895.JPG IMG_2896.JPG IMG_2897.JPG


    Here is a close-up shot of the old (top) and new (bottom) hot air flap control pods.
    IMG_2898.JPG

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    These writeups are incredibly well put together. I don't know how you do this and still have time to actually finish the job. I usually start out with good intentions of taking detailed pictures of everything, but usually something goes pair shaped shortly after starting in and I end up abandoning the documentary in favor of saving the patient. If I get any good pictures, it is usually by accident.

    These screws utilize a 5.5mm (not 5mm, and not 6mm) head, so you MUST have a 5.5mm 1/4" socket on hand to remove them.
    Off hand, do you know of any other Allen bolts/screws on the car that take a 5.5? I have it in my wrench set but none of my 1/4" drives have a 5.5.
    Jon D.
    1994 E420
    1995 E420

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    I am not aware of any other fasteners on the W/C126 (or W124, for that matter) that utilize a 5.5mm head. But, someone like Jono would be able to provide a more definitive answer.

    You can purchase a 5.5mm 1/4" socket via Sears Craftsman. It's only a few bucks so probably worth the investment, if just to have a complete set. I do not have any other ".5" increment sockets or wrenches in Metric sizing - everything else is "whole numbers" from 6mm on up. I wonder why they even came up with a 5.5mm size fastener. Doesn't seem much logic given that it's an "in between" size.

    Thanks for the compliment on the how-to articles. GSXR is the master at photographic documentation, though.....

    Cheers,
    Gerry

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    5.5mm = 7/32 in SAE... try your 'Merican sockets before buying the 5.5mm metric. I don't have a 5.5mm, and haven't needed one on the W124 (yet). Very odd size.


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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Thanks to both of you for your answers. Gerry, if the 5.5mm is actually a 7/32, maybe the pod in your 126 was an American part used by MB. In any case, I don't have any 1/4" drive Allens in American sizes, so I'll check sears on the 5.5mm. The last time I was at Sears, though, I didn't see any 1/4" drive Allens. Did you have to order that 5.5 from Sears on-line?
    Jon D.
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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    It's not an Allen key socket; it's a regular socket. See the photos of part 2 with the pink "center flap pod". You will see several of the gold 5.5mm screws that held the housing to the outside of the heater box. I have some closeups that I'll post as Part 3 tonight.
    Attached Images Attached Images

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    My mistake. I do have the 1/4" drive 5.5mm socket in the picture above. Thanks, Gerry.
    Jon D.
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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    PART 2, CONTINUED

    In replacing the center hot air flap pod, you need to remove the rubber gasket on the bottom of the old pod, and place it on the new pod. Here are a few shots of the transfer of the old rubber gasket from the old pod to the new pod.
    IMG_2899.JPG IMG_2900.JPG IMG_2901.JPG


    And....inserting the new pod's flanges into their holes on the plastic housing. After this is done, then you can press on the retaining grommets. Use your fingernail and a flat-blade screwdriver to CAREFULLY press these retaining grommets on.
    IMG_2902.JPG IMG_2903.JPG IMG_2904.JPG


    To affiix the rubber gasket that fits between the housing and the heater box, I used some Gorilla Glue to tack it down so that it doesn't come loose during installation. This is a very tight space inside of the dashboard, with a lot of cables and lines that can knock the gasket loose. Furthermore, the gasket only sits on a couple of pins on the outside of the housing, so there's not much holding it in place when you press the housing into place on the outside of the heater box and start a couple of the 5.5mm screws in their holes.
    IMG_2905.JPG IMG_2906.JPG


    Next, let the Gorilla super glue dry for at least 15-20 minutes. Turn your attention to the defrost pod, which is the top-most pod and which is totally obscured by the top of the dashboard and the center console housing. You basically have to remove and install this pod by feel. It's actually perhaps a bit easier than it sounds, which is rare for anything having to do with pod replacement.

    First, take a look at the metal arm of the defrost pod, and how it mates into yet another white ferrule inserted into the lever arm of the defrost flap. You will want to take a flat-blade screwdriver and CAREFULLY and SLOWLY pry the end of the metal arm away from the white plastic defrost flap arm. The arm should come out of the ferrule and hopefully the ferrule remains lodged in the end of the arm. When I did this, the ferrule indeed did remain in place.
    IMG_2908.jpg


    Next, check out this view of the defrost pod. This is one of the very best views of this pod that you're going to see... Reach up and disconnect the two vacuum lines, noting which line goes to which nipple on the pod. As a guide, the red line with white stripe goes to the top-most nipple as the pod sits mounted, and the red line with the blue stripe goes to the bottom-most vacuum nipple.
    IMG_2909.jpg


    Basically what you want to do is to reach up through the top of the console area, grasp the pod, turn it on its base in a counter-clockwise motion, and remove it. Then carefully bring it down and out through the console opening.
    IMG_2910.JPG IMG_2911.JPG


    After the defrost pod is out, you can yet again turn your attention to the installation of the center hot air flap pod, which as you remember whose super glue has been drying for the last little while. Now comes the very difficult and delicate part of the job. When you removed this hot air flap pod, you should also have removed the little white ferrule from the end of the arm inside the heater box. You now need to re-install it. How you do this is to insert the white ferrule onto a long piece of wire, which you then thread the end of through the hole in the end of the hot air flap arm. This is so you don't lose the ferrule while re-installing it into the hole in the end of the arm. Trust me, if you were to lose the ferrule, it would disappear down into the black hole of the heater box.

    And, the ferrule is NOT available as a separate part from MB. Rather, you have to buy a heater box repair kit, which contains dozens of small parts, and the cost of this repair kit is around $40-50. A LOT of money to pay for a single, two-cent ferrule. So, take my precaution of threading this ferrule onto a piece of wire as a safety measure.

    Next, run the ferrule down the wire so that it is roughly in place near the hole. NOTE the orientation of the ferrule. You will be pressing it into the hole from the left, so that the plastic flanges are pressed rightward through the hole. See photos below for this action and orientation.
    IMG_2912.JPG IMG_2913.JPG IMG_2914.JPG


    Next you need to CAREFULLY insert the arm of the pod into the ferrule, also from the left to the right. Make sure the ferrule is rotated so that its indentation locks onto the metal arm's shaft. Once the arm is inserted and the shaft is locked onto the ferrule's cutout, then carefully rotate the pod/housing assembly into place. Then you can press it into place, and start and tighten the four 5.5mm screws that hold it to the outside of the heater box.
    IMG_2916.JPG IMG_2915.jpg IMG_2918.JPG IMG_2919.JPG


    Here is a photo of the center flap pod, mounted with vacuum line attached.
    IMG_2921.jpg


    Next up is the legroom flap. This is the easiest of the three center console flaps to do. Basically the installation is the reverse of removal. Press the pod into place on its metal mounts; it should click-lock into place against the outside of the heater box. Then, insert the end of the arm onto the sliding mechanism/arm of the leg room flap. Then press the rubber washer and metal retaining grommet onto the bottom of the shaft. You may -- as I did -- need to compress the grommet's flanges together a bit using a few light blows from a hammer, or (in my case) squeezing it a bit in a bench vise. This will increase its "bite" onto the shaft of the leg room flap arm.

    Here are a few views of the old and new pods together (including date codes) as well as a couple of shots of the leg room pod installation process.
    IMG_2922.JPG IMG_2924.JPG IMG_2926.JPG IMG_2927.JPG IMG_2928.JPG


    After re-installing the pod and affixing its arm to the leg room flap sliding mechanism with the rubber washer and metal grommet, the last step is to replace the black plastic "guard" that covers the sliding mechanism from the myriad of wiring bundles and vacuum lines in that immediate area. This prevents interference with the sliding of the flap when the vacuum pod actuates it. Again, it's a press fit. You need to be sure to get the correct orientation of the guard, as shown. It just pushes right into the heater box exterior using the three prongs on the guard.
    IMG_2934.JPG IMG_2935.JPG


    To be continued in Part 3....

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    PART 3: Housekeeping Chores & Center Console Reinstallation

    As I got into the job, and had the center console disassembled, a number of smaller, incremental tasks came to my attention. I decided "while I was in there" just to take care of these jobs because I had the time, parts and motivation to do them.

    These incremental jobs included the following:
    • Repairing an unraveling wiring bundle cloth tape wrapping
    • Lubricating the dashboard air nozzle mechanisms and flap lever mechanisms with grease
    • Replacing the temperature wheel temp indicator strip


    You can see these tasks illustrated in the following photographs.

    First, using my handy lifetime supply of Mercedes-Benz "Gleitpaste" for the sunroof mechanism, I took one of my wife's Q-Tips and used it to gently lubricate the sliding teeth mechanisms in the dashboard vent nozzles. These teeth mechanisms allow the vent's vanes to slide back and forth in a smooth motion. I lubricated all four dashboard nozzles -- both sides of the dash and the two center vents. I also, as indicated earlier, lubricated a couple of the air flap lever mechanisms that employed plastic teeth to slide back and forth when actuated by their respective vacuum pods. Overall these lubrication operations required under five minutes to complete.
    IMG_2929.JPG


    Next up, one of the wiring bundles for the car stereo plug had begun to come unraveled by being moved about. As you know most wiring bundles are wrapped with "sticky" cloth tape, whose adhesive starts to loosen and soften with age. Seeing as this tape had just begun to unravel, I was able to fix it by re-wrapping the couple of inches that had loosened, and wrapping the end of the tape with a couple of turns of black electrical tape to hold it in place. This should keep it nice and orderly for the next 24 years, hopefully.
    IMG_2931.jpg


    Then, it was time to do one more tasks, seeing as I had the ACC PBU (push-button unit) removed from the car. The previous owner of my car, a Dutch executive, had many years before had a shop replace the temp wheel label with a Celsius number strip rather than the stock Fahrenheit scale that came stock on US-model MB models. This strip had, as shown in the photo, below, always looked a bit worn and ratty, and was wrinkled and just didn't look that nice. I guess it had seen a lot of use over the years.

    Somewhat presciently, I had ordered a few extra Celsius temp wheel labels in 2012. They are available inexpensively from MB (I think they are around $5.00 apiece) so I had ordered several, with the thought that I would retrofit all of my MBs with Celsius labels in the future when I got around to it. So, I had these labels very handy on my garage work-bench, and decided that this was the perfect time to replace the ratty-looking one in my 560SEC.

    The part number for this Celsius number strip (which applies to 126, 107 and 124 PBU thumbwheels) is: 124 821 29 67. The corresponding Fahrenheit number strip part number is: 124 821 XX XX.

    So, I removed the PBU from the dashboard wood using a Philips head screwdriver, and then with a smaller Philips head screwdriver removed the bottom cover to expose the guts of the unit. This allowed me to get much better access to the temperature thumb-wheel.
    IMG_2938.JPG IMG_2937.JPG IMG_2941.jpg IMG_2942.jpg IMG_2943.JPG IMG_2946.JPG IMG_2945.jpg


    Then, after getting access to the thumbwheel, I carefully peeled up and removed the old paper label, and spun on the new Celsius number label.
    IMG_2947.JPG IMG_2948.JPG IMG_2949.JPG IMG_2950.JPG IMG_2951.JPG IMG_2952.jpg


    After that job was done, then it was time to start buttoning up the dashboard, as all of the pods in that area were now installed, and the area was maintained. Basically you just replace the two screws that hold the top of the vertical portion of the center column to the bottom of the dashboard, and the plug in and replace the ACC PBU assembly. Be sure to re-fasten the wiring and vacuum line bundle with the plastic zip-tie that is located behind the PBU assembly, before installing it. Then fasten the two screws into the bottom of the PBU that hold it to the center column frame.
    IMG_2954.jpg IMG_2953.JPG IMG_2956.JPG IMG_2957.JPG IMG_2958.jpg


    It's also a good time to replace the right-hand dashboard vent (it just presses into the dashboard after you compress the spring-loaded swivel-pins on each side - a better overall design than the W124 methinks. Before you do this, you also need to re-fasten the rubber diaphragm to the right side of the dashboard air housing. I did this by carefully removing the two plastic pins, putting them through the small holes in the rubber diaphragm, and then re-inserting the pins into the housing. Then you make sure that the end of the rubber diaphragm is fitted snugly around the square ends of the air channel. Basically, you fix it up just as you found it. The old adage applies "Assembly is the reverse of removal."
    IMG_2932.JPG IMG_2933.JPG IMG_2936.JPG

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    PART 4: The Last Pod & Wrapping Up

    The sixth and last pod is in a completely different area of the car -- it is located directly above and to the right of the gas pedal, next to the A/C systems expansion valve. So, it is generally independent of the other pods that are accessed from the front of the dashboard area.

    This last pod is the "scoop air flap" pod, according to Mercedes-Benz. To access it, you have to remove the carpeting on the driver's side of the console (between the gas pedal and the side of the center console) as well as the driver's side floor mat/carpeting, and the driver's side under-dashboard panel.

    First of all, remove the carpeting on the driver's side. Then, you need to remove this side carpeting on the side of the console. The carpeting is only held on by a single screw, which is deeply recessed into the center console area and unsfastened with a medium-sized Philips screwdriver, as shown below.
    IMG_2973.JPG IMG_2961.JPG


    Next, remove the trim panels that cover the screws that hold the under-dash shelf/panel to the bottom of the dashboard. You need to pry these trip strips up from the left side to the right, because the right side has a "hook" that is very easily broken if you are too rough. And furthermore, these types of trim pieces are increasingly "no longer available" from Mercedes, so it behooves you to take extreme care of the trim pieces you have. A small to medium flat-blade screwdriver works well to pry the ends of these small trim cover panels up for removal.
    IMG_2959.JPG IMG_2978.JPG


    After the two trim pieces are removed from the under-dash tray area, the three screws that hold it to the dashboard are exposed. It's a simple matter to remove these three Philips head screws, as well as the one Philips screws and two larger plastic press-in fasteners that hold the under-dash panel to the knee bolster under the dashboard. It's all self-explanatory once you see it. The under-dash panel then pulls straight out of the car after all of these fasteners are removed.
    IMG_2960.JPG IMG_2976.jpg


    From there, once the floor carpeting, under-dash panel and the side console carpeting panel are removed, this is what you'll see.
    IMG_2962.JPG


    Then, you need to get under the dashboard (preferably on your back, with your head near the brake pedal) and look upward above the gas pedal to find the sixth "scoop air flap" vacuum pod. Here it is (below) although it is just a smidge more accessible in real life than it looks from this photograph.
    IMG_2963.jpg


    The biggest impediment to access is the large tubular support bar, as shown in the photo above, of which there is really no way to get around.

    To access the pod for removal, you need to first unplug the rubber vacuum connection on the bottom of the pod. Then you need to take a long, flat-blade screwdriver and reach up and CAREFULLY pop off the pod's metal arm off of the scoop air flap's plastic actuator arm. I wasn't able to get a photograph of this, but it is very similar to other pod arms. The main thing here is to use CARE and CAUTION with the tip of the screwdriver, so that you don't break off any of the three small plastic retaining lugs that go through the hole in the end of the pod's metal arm and mate the two items together. If you happen to break off any of these lugs, then emergency surgery (likely with a cotter pin or other fastening device) is in order, but that is outside the scope of this how-to, simply because I didn't break off any of the plastic retaining lugs that press into the pod's metal arm hole.

    Unfortunately access was so tight that I was not able to photograph this operation, but rest assured that it is very similar to other pod replacement operations. Once the metal arm is disconnected from the scoop air flap arm, then you use your fingers to twist the pod off of its metal mounting base (same as with most of the other pods) and then you work it down and out of the car. The fit is tight, so it may require a bit of force to "force" the old pod past various hoses and fittings.

    Here is a comparison of the old and new (replacement) pods.
    IMG_2964.JPG


    To get the new (replacement) pod positioned, it's essentially the reverse of removal. You may need to push hard to get the new pod past the items that are partially in the way. Once the new pod is in position, then you will find that its fully extended metal arm may be an impediment to getting it positioned in the right way to lock the pod's tangs into the metal bracket that holds it. I strugged with this for well over an hour in the Houston heat, on my back, cursing and swearing. Finally I decided to take a break and "sleep on it."

    That was just the ticket to find a solution. The next night, after work, I approached the problem with a fresh set of eyes. I quickly found that the pod's arm was conflicting with parts up near the air scoop flap arm, so I decided a solution to use my Mityvac to connect to the pod, apply some moderate vacuum, and "retract" the metal arm into the pod by about 3/4". This gave me the clearance I needed to rather quickly position the pod into its metal bracket and turn it into place to lock it down. Then I released the applied vacuum from the Mityvac, and was able to use my long flat-blade screwdriver to carefully (once again...) position the hole on the end of the metal pod arm, next to the three-pronged tang on the end of the air scoop flap arm, and pop the end of the metal arm onto the tangs and lock the arm/flap together. A delicate operation, for sure, but once the Mityvac solution was determined and applied, an installation that only required about 15 minutes.
    IMG_2965.JPG

    A view of the new (replacement) pod in place is here. After connecting the pod's metal arm to the air scoop flap, be sure to reconnect the rubber vacuum fitting to the bottom of the pod to get it re-integrated back into the ACC system.
    IMG_2968.jpg


    Once the last pod was mounted, it was time to take my ship vacuum and vacuum out the dust, disintegrated foam pieces and dirt located in the carpet-less driver and passenger side footwell areas. Five minutes with the shop vac made short work of these areas and tidied up things nicely....
    IMG_2970.jpg IMG_2971.JPG


    As a side note, one special item that I wanted to point out was the new foam-rubber (with metal spring interior stiffening) "A/C condensation drain tube" that I had installed last fall. There is one on each side. This tube is a very common item that disintegrates over the years, resulting in condensate leaking into the footwell area of the car. If you haven't replaced this cheap item (last I checked it was around $10 from MB) it's now an excellent time to do this. You can see it here as the light-gray flexible tube.
    IMG_2969.JPG


    From there, it's time to start buttoning up the driver's side under-dash and console area, replacing both panels and then the carpeting.
    IMG_2972.JPG IMG_2974.JPG IMG_2975.JPG IMG_2977.JPG IMG_2979.JPG IMG_2980.JPG


    Now would be a great time to run a functional check of your newly pod-ified ACC system. A quick, five minute test after reconnecting the battery (temporarily) and starting the engine, showed a frost-covered windshield from the ice-cold A/C. Mission accomplished.
    IMG_2981.JPG IMG_2982.JPG


    Then begins the home stretch of reassembling the rest of the center console -- mainly the lower wood/switch pieces, the coin tray, ashtray, and glove-box areas between the seats. Routine stuff for most of us Benz DIYers.
    IMG_2983.JPG IMG_2984.JPG IMG_2985.JPG IMG_2986.JPG IMG_2987.JPG


    Part 5 will be the conclusion ... re-installing the passenger-side airbag and carpeting.

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    PART 5: Finishing Touches & Buttoning Up

    Tonight's job was basically just to put the finishing touches on everything and replace the passenger side airbag, under-dash panel, kickplate, carpeting and roll-top "glovebox" between the seats on the center console. This job took about 1.5 hours to complete, taking my time and cleaning things up as I went along. I also applied a coating of 303 Aerospace Protectant to my dashboard as a finishing touch.

    One note with regard to this job: it is inherent to this type of job that you will suffer plenty of scratches, slices, cuts and bruises on your hands in the process of doing the work. Any work in involving car dashboards and the innards always involves plenty of sharp edges and surfaces that slice and dice your hands. So ... if you are considering doing this job ... beware that it will wreak havoc on your hands. You can see the scars, scrapes and scabs on my hands in the photos below, from the last four days of doing this job.

    The first step in the conclusion of the job was to replace the passenger-side airbag. This entailed replacing two plates (one on each side) and attaching them to the dashboard with four screws, plus to the underside of the top of the dashboard with one screw on each side. The basic steps in the process are shown here.
    IMG_2988.JPG IMG_2989.JPG IMG_2990.JPG IMG_2991.jpg


    The next job after the airbag hardware was installed, was to put back on the under-dash panel and shelf that goes immediately under the airbag. This attaches with three screws into the front of the dash, and two large plastic pins that press into the knee bolster underneath the dash.
    IMG_2992.JPG IMG_2993.JPG


    After the under-dash panel was installed, some slight adjustment of the rubberized air-seal at the edge of the dashboard, and the corner of the panel, needed to be tucked into the trim piece that edges the door frame.
    IMG_2994.JPG IMG_2995.JPG


    After the under-dash panel is installed, it's time to re-connect and then carefully re-install the passenger-side airbag. Then re-install the trim piece (CAREFUL...brittle plastic) that covers the screws that affix the under-dash panel to the front of the dashboard.
    IMG_2996.JPG IMG_2998.JPGIMG_2999.JPG IMG_3000.JPG


    Then, reconnect the airbag plug in the passenger-side footwell.
    IMG_3001.JPG


    Secure the airbag with the long bolt, mounted up into the dashboard from underneath. Use the long extension and 10mm 1/4" socket to "start" the bolt into its hole, and then snug it up with the ratchet attached. Hold the passenger side airbag in the desired position while doing this, so that its surface is flush with the surrounding dashboard panel.
    IMG_3002.JPG IMG_3003.JPG


    Here's a view of the passenger side, all buttoned up, with the carpeting replaced and all in order. Last little job was to re-attach my Becker iPod jack onto the carpeting between the driver's side seat and center console.
    IMG_3004.JPG IMG_3007.jpg


    Job Complete !!! Beautiful "mushroom" interior, eh?

    Cheers,
    Gerry

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    I'm exhausted just reading all this. Great post.
    Last edited by emerydc8; 07-17-2013 at 06:02 AM.
    Jon D.
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    1995 E420

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Incredible tutorial, absolutely fantastic! Thank you Gerry, thank you thank you!

    I made this entire page into a pdf, including the questions and comments, since I will be making this repair on my 300SEL and my 500SEC. That way, I can have it with me in the car on my Ipad without having to print the paper.

    Definitely THE BEST tutorial on MB repairs I have found. Again, thank you so much Gerry.

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods



    You are very welcome. If you come across any problems, or differences with what I posted, please feel free to post them here.

    The best thing to do is to perform this job over a two-day weekend (or start it on a Friday night, and finish on Sunday). That way you only have to work a limited number of hours per day on the job. Thankfully, it is JUST possible with the W126 that you don't have to remove the dashboard to replace all of the pods. With the W124 (this site's main focus), the dashboard must be removed to change out several of the pods.

    For the W126, the top-center pod, and the one down behind the gas pedal/console area, are the worst ones. The ones behind the glovebox/airbag area on the passenger side are probably the easiest, and quite often these pods (which control the fresh air intake flap) are the ones that go bad. I highly recommend changing out all pods at the same time, rather than doing one or two at a time. That way you know that the entire system is baselined and that all pods are working.

    If your A/C system is properly charged, it is AMAZING how much difference that having a working fresh air flap makes in terms of having a COLD cabin when the A/C is on. If the fresh air/recirc flap is not working properly, it will continue to admit warm outside air, which mixes with the cooled air, and never allows the cabin to get truly as cold as it should be.

    Good luck! Let us know how things go.
    Cheers,
    Gerry

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    This is the best. I have seen many tutorials on numerous MB forums. The scripting and pictures are great. Thank You. Topgun.

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Quote Originally Posted by topgun View Post
    This is the best. I have seen many tutorials on numerous MB forums. The scripting and pictures are great. Thank You. Topgun.
    I'm glad it was of assistance. That's why I do these tutorials -- for folks who need the help to accomplish the repairs. Thank you for the feedback.

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Many thanks for your comprehensive tutorial. I am about to do the same job on wife's w126 300SE. Greetings from Australia.
    Regards Burcon5

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    I stumbled upon a writeup that deals with the expansion valve, but parts are helpful to readers if also working on the lower left POD near the valve.
    Attached Files Attached Files
    1994 E500
    249/275 - 8F19 or 8F32 or 8320

    1991 560 SEC
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    2014 E350 Cab 799/264

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Thanks so much for this post. I fixed the dreaded 'center vent' issue on my W126 last night. The only thing I struggled with was the heavy piece of 'insulation' - almost a rubber membrane, that covered up everything under the dash behind the glovebox. I couldn't get it out, and I couldn't keep it out of the way, so it made the entire process painful. Took me about 3 hours start to finish just to replace those two pods because of large hands and small spaces

    Turns out the far right (passenger side) pod was bad and was leaking air. Once it was replaced, the system functioned normally. But since I had everything apart, I went ahead and replaced them both. Sure was nice to have air conditioning this morning that wasn't coming out the defroster vents. I do notice a small bit of air coming out the def vents, however - not sure where it is coming from, but on warm, humid mornings in NC, we have a lot of those. Had to cycle the wipers a few times to clear the condensation off, but at least my center vents were blowing strong! Unclear what the "scoop" pod does, so off to do some more research on that. This post made replacing the two pods I needed to replace, much easier. No broken clips, everything works fine.

    I did try rebuilding the pods using a kit from Performance Products - one was successful, the other was not. Going to continue to futz around with it and see if I can figure out what is wrong. But at least have a spare and can swap the levers if I ever need to in an emergency. I'd still buy new pods just to be on the safe side.

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    HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    You have a short stroke and long stroke defrost pod. A very sage MB vet of 30 years suggested a way around this. Cap off the bottom port on the distributor or 7 valve solenoid switch. Take the vacuum line from 7 and T connection to the line and Port 4. This will prevent the trickle of air, especially on auto. Same applies to the W124.

    Here is picture a reader may find useful at some point... Take note that the solenoid switch is that of a W126 and I have not researched if the same PN listed in that pic are for a W124. This picture is conceptual over two chassis and you should review proper PN for your specific car and not rely on those listed. (damn lawyers)
    Attached Images Attached Images
    Last edited by nocfn; 08-23-2017 at 09:48 AM.
    1994 E500
    249/275 - 8F19 or 8F32 or 8320

    1991 560 SEC
    199/268
    2014 E350 Cab 799/264

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Quote Originally Posted by YeahRightNC View Post
    I did try rebuilding the pods using a kit from Performance Products - one was successful, the other was not. Going to continue to futz around with it and see if I can figure out what is wrong. But at least have a spare and can swap the levers if I ever need to in an emergency. I'd still buy new pods just to be on the safe side.
    The PP rebuild kits work fine for single-chamber pods of the proper diameter. However the kits do not work well for the "large lift" portion of dual-chamber pods, the total movement is less than factory. Click here and check out the photos.

    If a pod is NLA then this kit may be your only option, but if still available new, it would be better to buy complete new pods.

    Dave M.
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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Last I knew, all of the W/C126 pods were still available either from the aftermarket, or MB, or both.

    I believe that at least one of the W124 specific pods is no longer available.

    Two other notes, to reiterate (I get asked this question regularly, and have seen misinformation posted on the Banzworld site):

    • It **IS** possible, as this HOW-TO shows, to replace all six of the 126 chassis ACC vacuum pods WITHOUT removing the dashboard from the car.
    • It **IS NOT** possible to replace all of the 124 chassis vacuum pods without removing the dashboard. To repeat, to replace all six 124 chassis pods, one MUST remove the dashboard from the car.


    Cheers,
    Gerry

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Ok just did this job and the write up was awesome. Couple of things, on the dash pod that I think is the defroster one, I changed the hex head screws to phillips. It makes it a tad easier to install them. Second I have a glove box not a air bag and you have to remove the interior of the glove box. Its easy, there are 7 grommets. Take a screwdriver and pop up the center push pin, then once its up, take out the barrel. Remove the glove box interior and you get some access.

    Second thing, Gerry, I think the drivers side kick panel was the worst!!!! I spent an hour under the dash trying to get that sucker. Ok here are some tips. Use a very long screwdriver and wedge it between the ferrule and the pod actuator. Slowly twist the screwdriver and it will pop out of the ferrule. Now that that actuator is loose, take a pair of channel locks and grip the pod. It will have to be a large set, put you can get just enough on it to grip it. Twist it counter clockwise and it should pop off. Now the hard part. Finding a way to get that sucker out. It really won't fit, but you have to force it. My old one came apart, which I did not care. To get the new one in, I had to force it up between the round support bar and the climate control housing. Its close but will go. Only other thing you could do to make it easier is to find a way to remove that support bar. Second thing I did was to connect the actuator arm first, then slip the pod into its resting place. I marked the pod on the side with a magic marker so I would know which of the tangs went where on the metal bracket. I also did find the drain tubes for the air conditioner toast. Gerry if you have the part numbers can you send them. I am hearing they are not available anymore?

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Okay, I just did the center vents pod. What a royal pain in the rear!

    Gerry, I have no idea why yours was so relatively easy. My big challenge was snapping the 90 degree arm into the ferrule. The flap just kept pushing away, toward the front of the car. I finally started using a dental pick to hold the flap toward me so I could finagle the 90 degree arm in. Then the dagnabbit ferrule would rotate. Start over. It was just about the final straw when I lost my grip on the dental pick and incredibly, it dropped slow motion into the small rectangular opening through which all this work is performed, and disappeared into the evap box. Unbelievable.

    I immediately started wondering if it was big enough to prevent movement of any flaps. I had no desire to pull the dash right now. For some reason, it occurred to me to reach into the box from the flap on the passenger side (I had removed the righthand duct already). Gratefully, I was able to retrieve it.

    The final answer for me was a helper. I used a longer pick to keep the flap towards us and held a bright light. My mechanic buddy worked the 90 degree rod. The ferrule kept rotating out of place for him, as well. I filed the very end of the rod so that it was very slightly tapered to slip into the ferrule. I also lubed it. We finally got it started and a long screwdriver supplied the necessary force to gently press it home into the ferrule.

    My gosh, what a challenge that was. And what a thrill to have center vent cooling again!

    Thanks for the great write-up. It was super helpful.

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    It was much easier replacing all of them with the hvac box on my bench
    1994 E500
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    1991 560 SEC
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    2014 E350 Cab 799/264

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Quote Originally Posted by nocfn View Post
    It was much easier replacing all of them with the hvac box on my bench
    Show-off!


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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Glad the write-up has been helpful for folks. It’s always interesting to see how much it is accessed.

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Quote Originally Posted by gsxr View Post
    Show-off!

    I don’t wish evaporator change on anyone, ever.
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    1991 560 SEC
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    2014 E350 Cab 799/264

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Quote Originally Posted by nocfn View Post
    I don’t wish evaporator change on anyone, ever.
    I'd actually like Gerry to do an evap R&R, so he'd create one of his in-famous How-To procedures with 500 pictures. That would be awesomesauce.


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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Quote Originally Posted by gsxr View Post
    I'd actually like Gerry to do an evap R&R, so he'd create one of his in-famous How-To procedures with 500 pictures. That would be awesomesauce.

    I agree, the world is soon to be hit with this over the next 5 years!
    1994 E500
    249/275 - 8F19 or 8F32 or 8320

    1991 560 SEC
    199/268
    2014 E350 Cab 799/264

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Quote Originally Posted by nocfn View Post
    I don’t wish evaporator change on anyone, ever.
    Quote Originally Posted by gsxr View Post
    I'd actually like Gerry to do an evap R&R, so he'd create one of his in-famous How-To procedures with 500 pictures. That would be awesomesauce.

    If it comes up, I'll do it. Knock on wood, but my E500 is still running on its original evaporator as well as the original vacuum pods (I have a full set of spares for when I need to change them).

    And you can bet there will be a HOW-TO on it. The 124 and 126 Pod Replacement HOW-TOs, as well as the M117 and M104 Top-end Rebuilds, and the M117 EHA Replace/Adjust, have seemed to garner a LOT of hits. I believe all of these threads are linked from numerous other sites, including "The Site That Shall Not Be Named" (TSTSNBN ... aka nocfn/281lxm's favorite hangout), which drives a lot of traffic to them.

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    BOLLOX
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    249/275 - 8F19 or 8F32 or 8320

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Great write up. Bought all the new parts required. However, The ac is blowing out the defrost vent and not the front vents. Any suggestions. FYI, I have used many of your write ups to keep my 1991 560 sec running great. Love the car and your write ups. Thank you

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    You have a vacuum diverter pod that is not working. You need to test all of the pods for vacuum at the "christmas tree" when you take the passenger airbag out, on the left side. That should identify the culprit. It's all in the HOW-TO, and you can see the christmas tree in some of the photos.

    The most common pods that fail are the ones behind the passenger side airbag -- there is a pair of them, and they are easy to get to/replace.

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    Thank you for the quick response - that will be tomorrow's project. I will keep you posted. One last question what is the part number ?

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    Re: HOW-TO: Replacing C126/W126 ACC Vacuum Pods

    The information is shown for the pods in this thread:

    https://www.500eboard.com/forums/showthread.php?t=11749

    Christmas tree info: https://www.500eboard.com/forums/sho...l=1#post149029

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