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Thread: Evaporator Replacement

  1. #1
    Senior Member jaymanek's Avatar
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    Evaporator Replacement

    Hi All,

    Unfortunately the 500TE doesnt want to hold its A/C gas.
    It would lose its gas in 2-3 days.

    I have tried some Wurth A/C sealer and it is currently working.. But its bugging the hell out of me. I dont like these temporary fixes.

    Yesterday, in extreme (well for the UK) heat, the A/C was struggling.. Cool but not as cool as my SEC.
    So im thinking its lost some gas.

    I want it right so going to have to just get on with it.

    I have watched the time lapsed video of a very professional japanese man doing the job, seems a very lenghty job but doable.
    Also read some threads on here.

    I am going to try and get through the next couple of months and then tackle it when I have more time.

    Im getting all the parts together.

    1) Evaporator A1248300758
    2) Valve Unit A1408300484
    3) O Rings A1409970745 & 0845
    4) Vac Pods A1248003075, A1248002975, A1248000375, (A1248002675, A1248000275, A1248000975 NLA FROM MB. EDIT: BUT NOW SOURCED ON EBAY)

    Any other parts I need?

    Any other tips or advice?
    Last edited by jaymanek; 3 Weeks Ago at 03:59 AM.

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  3. #2
    E500E Guru JC220's Avatar
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    Re: Evaporator Replacement

    Has dye been added to the system and a UV torch used to make sure there are no leaks in other (more accessible) areas? Also look up at the drains above the trans tunnel to see if any dye is visible there. I would sure like to know all other areas were fully checked for leaks before delving into taking the dash out
    1987 w124 200 - 3.6 AMG build | 1990 w124 300E-24 | 1992 w124 500E

    1994 320CE Sportline | 1997 w140 S280 | 2007 w211 E220CDI

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  5. #3
    Senior Member jaymanek's Avatar
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    Re: Evaporator Replacement

    Hi,

    Yes im pretty sure all other areas are leak free. I can actually smell gas inside the car...actually i could before the sealant was added.

    We have an A/C sniffer here at work, that goes ballistic when its near the bulkhead area.
    At first I thought it was the seal to the two pipes out of the bulkhead, as these pipes were renewed when I built the engine... But I think the issue is older.. Im guessing the A/C hasnt worked for a while.
    I wouldnt have noticed when I picked up the car as it was fairly cool in late September.

    I may also change the condensor if I can find a genuine one.. Just for completeness. I think 500E condensors are NLA?

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  7. #4
    E500E Guru nocfn's Avatar
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    Re: Evaporator Replacement

    When My evaporator went, the R134 smelled like a box of band-aids and the green fluid came out of the drains. Also, it will leave an oily residue in two circles on the ground if it doesn't have green dye in it after the condensate goes away.

    As for the dash, take your time get lots of zip lock bags and a marker to label and keep track of every part. It is time consuming and tedious, but not a difficult task. I have done it twice on the C126. A tip, if doing this indoors open your windows, perhaps even your sunroof (my hope is you can cover the with the appropriate car cover) and finally push your seats all the way back on bring the steering wheel all the way out to the end of the telescopic length. Then pull the battery cable. If you have not replaced your ignition switch ever, or replaced the vacuum pods, now is the time for such easy access endeavors.
    1994 E500
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  9. #5
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    Re: Evaporator Replacement

    Your opening up the system for some time to Remove and replace a evaporator.

    You'll need a RD (reciever drier), o-rings. Some replace the 2 pressure sensors on the drier. The factory oil is PAG 46, you will need some replacement oil. Ideally, you want to flush the oil from the condenser since the oil is hydrophilic(sp). Remove the compressor and drain into a clean container. Then you can replace the oil. I would read the FSM closely. Last 124 I did is still going strong... been nearly 10 years and 75,000 miles.

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  11. #6
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    Re: Evaporator Replacement

    Big job labor wise..

    Have you done A/C work before? Honestly, I've seen good stop leak work for many years.

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  13. #7
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    Re: Evaporator Replacement

    Any time an A/C system is opened up (i.e. evap replaced; compressor replaced; lines opened up,, etc.), it should have all refrigerant + oil evacuated ("recovered") through the proper machine/procedure. When you put the system back together, you ideally need to start from "zero" so that you can add the appropriate amounts of refrigerant and oil.

    Most home mechanics don't have a refrigerant recovery machine, so it's probably best to have this evacuation work done by a competent shop. It's generally not too expensive to have the refrigerant and oil removed. You don't want to vent refrigerant to the open air.

    Do you have a set of A/C pressure/vacuum gauges? And appropriate lines and fittings?

    Once the system is repaired and everything installed, then it's best to have a vacuum pump to pull vacuum in the system for a full hour; this will remove all moisture and air from the system (this is important). The vacuum procedure will also tell you, before you add refrigerant and oil to the system, whether the system is tight and holding vacuum. If the system is holding vacuum, then you can re-add the specified amount of refrigerant and PAG oil (note that R-134a systems use PAG oil as samiam44 says; R-12 systems use mineral oil ... and the two types of oils are NOT compatible).

    A/C work isn't rocket science, but it can be a PITA to do it right, and it requires some specialized equipment -- some of which is out of reach of the home mechanic. Here in the US, it's $400+ just to purchase a refrigerant recovery machine. A/C gauges and vacuum pump will start at $150-250 and up.

    Pulling the dash on a 124 isn't as horrible as some make it out to be, but definitely give yourself the time you need. I reckon that pulling the dash and replacing the evaporator and putting things back together again is a full weekend's work, as long as you are not rushing yourself. Other work like replacing the condenser is additional.

    More info on 124 dash pull + pod replacement is here (though evap removal/replacement is not covered): https://www.500eboard.com/forums/showthread.php?t=1370

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  15. #8
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    Re: Evaporator Replacement

    If you are doing the evaporator... I'd seriously consider going all out with new everything. New Denso compressors are cheap insurance. The manifold hose might be expensive, but if it's original, I'd think about that as well (either new, or have an AC shop replace the hoses). AC work is miserable, it's one of those things to do right the first time, so you don't have to touch it for another 20 years.

    That said, if you are losing an ENTIRE charge in 2-3 days, and it's not an O-ring (which are all in the engine compartment)... the leak may be too large for chemical sealants. If you are only losing a partial charge in 2-3 days (still pressure in system, but weak cooling air out the vents) it's probably borderline. I think CryoSeal or Cliplight websites / instructions specify the acceptable leak rates for their products to work. I'd be awfully tempted to try Cliplight Super Seal Total Auto (976KIT) as you wouldn't have much to lose. Note it can be a PITA to get the sealant products to enter a fully charged system, you may need to apply moderate heat to the can.

    Best solution of course is a new evaporator, all new vac pods, the whole enchilada... but ugh, the labor time. Pulling the dash isn't too bad to replace the pods, 8-10 hours for a first timer, by the fourth time I got it under 5 hours start to finish. The evaporator is a whooooole 'nuther world, I've never done it, but from what I hear as first-time DIY plan on 40 hours and throw a party if it goes quicker.


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  17. #9

    Re: Evaporator Replacement



    Conversation opened. 1 read message.
    Jaymanek: When I contemplated R & R my evaporator I found this very detailed 'how-to' write up with lots of photos. You may find it helpful. Sorry--but I don't know how to post a direct link. In my case I pulled the dash, center console, cowling water drains etc. but decided the evap. was beyond my abilities so had the car towed to a shop and had it done. Towed the car home and re-installed everything.
    You may want to replace the heater core at this time. Its only a fraction of the cost of an evap.

    Regards,

    Peter Weissman

    ADMIN EDIT: Added link to PeachParts thread with detailed evaporator replacement instructions:
    http://www.peachparts.com/shopforum/...lacements.html

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  19. #10
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    Re: Evaporator Replacement

    Quote Originally Posted by geraniumtr View Post
    Jaymanek: When I contemplated R & R my evaporator I found this very detailed 'how-to' write up with lots of photos. You may find it helpful.

    http://www.peachparts.com/shopforum/...lacements.html
    Thanks for the link, Peter! Note that in post #38, it turns out the OP likely did not have a leaking evaporator - ouch.

    Post #43 shows what a really bad evaporator looks like - photo attached below.
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  21. #11
    Senior Member jaymanek's Avatar
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    Re: Evaporator Replacement

    Thanks all.

    I have A/C equipment here at work.

    It already had as many new components as I could get hold of.. So drier, pressure sensors, various pipes and hoses. Original A/C pump as this looked fairly new and I couldnt get a new MB condensor so reused.
    No signs of leak at condensor.

    I have completely vac'd and refilled the system many times now.. It holds vac and our machine does a pressure test before letting gas in... so it passes all these phases which indicated the leak is very small.
    This is why i tried the Wurth sealant.
    But its bugging me, I want it right!

    I will tackle this job, just not at this moment. I am getting all the parts together for now.

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  23. #12
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    Re: Evaporator Replacement

    If the Würth sealant does not operate under the same principles as Cryoseal or Cliplight... if it's not the same, and won't be effective in fixing an evaporator leak. Cryoseal and Cliplight are specifically designed to fix evaporator leaks.

    Got a link to the Würth product you tried? If it was this stuff... pretty sure it's not the same type. I can't find the instructions for it though, or even a close-up photo of whatever it says on the Würth can.


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  25. #13
    Senior Member jaymanek's Avatar
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    Re: Evaporator Replacement

    Thats the stuff.. Im sure it said it will fix any small leak... The cryoseal seemed to be difficult to get into the UK.

    Its working so far, after about 3/4 weeks, I still have cool air... just not sure its as cool as it should be.

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  27. #14
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    Re: Evaporator Replacement

    First time I did the dash pull and evap it took about 16 hours with no assistant(an extra set of hands will make it a lot easier). Really not that terrible, I was actually surprised at how easy the dash and center console removal was comparatively to BMWs of the same era

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    Re: Evaporator Replacement

    Quote Originally Posted by S70/2 View Post
    First time I did the dash pull and evap it took about 16 hours with no assistant(an extra set of hands will make it a lot easier). Really not that terrible, I was actually surprised at how easy the dash and center console removal was comparatively to BMWs of the same era
    Yes, but we're pretty certain you are an alien with superpowers, based on the mean green Uberwagen build. Scheduling double your time for mere mortals is probably the safe thing to do...


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  31. #16
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    Re: Evaporator Replacement

    Some photos to let you know what lies beneath, last one is a picture of what real summer heat is

    I can't recall the exact size but I think it was 7/8" heater hose I used for the drains since the foam tubes disintegrated into dust
    Attached Images Attached Images

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  33. #17
    Senior Member jaymanek's Avatar
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    Re: Evaporator Replacement

    Thanks!

    Guess what, today it is ice cold again!

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  35. #18
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    Re: Evaporator Replacement

    The manifold hose is the expensive item- you can buy it new( I think), but I bet you can find someone in your local area to rebuild it for a minimal cost.

    The MB condensor(Behr) was a smaller diameter tube- fin/tube design. Perform fairly well. Used are plentiful here state side if you run into problems with yours. ND-8 is the correct oil for your compressor. As Gerry noted, you can recover oil+ freon, but that doesn't get all the oil out of the system.

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  37. #19
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    Re: Evaporator Replacement

    If you think it might be just charge relate- pay to have someone suck out the R134a and then recharge the system with 1kg.

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