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Thread: HOW-TO: Replace W124 Blower Motor & Regulator

  1. #1
    Senior Member makemann's Avatar
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    HOW-TO: Replace W124 Blower Motor & Regulator

    My 500E is a 1992. Your newer E500 may be slightly different, but I hope this helps.

    There are great instructions on how to remove the blower motor (000-830-82-08) that Gerry posted here, but my photo instructions are more for removing and replacing the Blower Regulator (124-820-27-10).

    I bought this stuff...



    I would recommend the OEM regulator if you can afford the $551. This KAE part was $182. I just had to replace the ETA and tapped into the expendable fund once too many this month.


    Here's the regulator.


    No smart comments on the yellowed expansion tank and, yes, I need to buy a longer hose to the tank and re-route it along the passenger side.

    Okay, now that we got that out of the way. Follow the linked instructions above to remove these items...


    Remove rubber molding and within five seconds you will do this on the hidden clips...


    In removing some of the parts, I've noticed that there were various fasteners missing. For example:



    If you know the part number, please shoot it my way!



    That one was there.


    That one was not there.


    Again, if you have a part number for this, lemme know!


    All parts removed to expose the blower motor cover. Unclip 8 clamps and remove cover.


    Cover removed. Pay attention to how the wires are routed. Remove the two screw and unclip the clamp holding the motor in place. Remove blower motor.


    With blower motor out of the way, unscrew the two screws holding in the blower regulator.


    Unplug the blower regulator. The plug is located on the driver-side firewall. After this step, the real fun begins.

    The blower regulator is held in place by two screws on the top, adhesive foam tape along the edge that adheres to the blower motor housing, and finally by a locating pin on the bottom of the part. Shown here on the new part.


    After removing the two top screws and breaking the last of the 25-year old crumbling, disintegrated foam tape, you need to pull straight up on the regulator and push the top of it toward the driver-side. This allows the locating pin to pull out of its hole in the bottom of the blower motor housing.

    You need to be extremely careful not to push the old part into the fins of the evaporator. The concave blower motor housing has little to no flex, so it takes a lot of pulling power to dislodge the part.

    I felt like Miles Davis at his most creative with the new and varied combinations of scat that flowed out of my mouth.


    Once the locating pin is dislodged, just fish out the part.


    I'm going to mount this above the fireplace.


    Interestingly, I did not bend the porcupine quills on the old one. As much as I wanted to, they were in this condition in situ. Perhaps it was Hans who did it 25 years ago! Poor fellah.


    Reuse the rubber pin locating piece and install the new part. Install was the exact reverse. Again, be careful not to hit the evaporator fins.


    There was disintegrated foam on the top cover of the blower motor housing. It keeps it snug to the top of the blower motor. I removed the old foam and installed new.




    I tested the HVAC system before buttoning it all up. Blowing COLD and QUIET! Success!

    I used Simple Green to clean all the parts and protected them with 303 before reinstalling. Voila, it all went back together smoothly.

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  3. #2
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    Re: HOW-TO: Replace Blower Motor & Regulator

    Awesome write-up! Thanks for posting this. Glad you were able to fix the problem!

    Dave M.
    1997 E420 (Bugeyes)
    1994 E420 (Blondie)
    1994 E500 (Q-ship)
    1992 500E (Mach 5)
    1987 300D (Sportline Stage 2)
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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    Very good. You will be glad you did the regulator too.
    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: Replace W124 Blower Motor & Regulator

    I have also found that those black "flower" plastic screws at the inner firewall, and the metal clips, are often missing. When I did my E320 wagon top-end job a few years back, I scrounged at wrecking yards for new flower screws and clips, and I replaced (a part specific to the M104) a plastic retainer for the upper wiring harness that fastens it to the inner firewall, and replaced the center firewall section with a used one in much better condition.

    As I remember it, I could not find the "flower" screws in the EPC, either. Fortunately they are common in the wrecking yards. I'll try to remember to snag a few next time I find some late 124s in the yards.

    These could also be a huge money-maker for the Stevester, in addition to his increasingly lucrative M119 cam oiler tube business.

    Cheers,
    Gerry

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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    Mak,

    Another job well done.

    I'm sure everybody here is greatful and felt your pain with the Doc-U-Pics.

    Congrats on your success!!
    Terry

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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    It's a PITA to document all of the steps, and then repost everything here and relive the process as you post the photos. However, it is invaluable to others in the future when we have to do these jobs. Not to mention adding a lot of time while you're having to both photograph things and work at the same time.

    Thank you for taking the time and effort to document this job. I know this HOW-TO will become one of the more "popular" ones in the future.

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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    I know you can appreciate the amount of time that goes into these How-To posts. Glad I could finally contribute something of value. I've gained way more than I've given.


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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    The concave blower motor housing has little to no flex, so it takes a lot of pulling power to dislodge the part.

    I felt like Miles Davis at his most creative with the new and varied combinations of scat that flowed out of my mouth.
    Just curious... was I exaggerating about how fun it is to R&R the porcupine? You didn't comment much about the installation of the new one, that was where I had the most trouble. The new, thick foam was hard to compress while lining up the screw holes, trying not to cross-thread...


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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    Dave, while I've only worked on later (facelift) W124 blowers, and can't speak for Makemeister with his pre-facelift car, I don't recall the blower motor and regulator replacement (particularly regulator) being all that big of a deal, nor particularly tough to do.

    What I do remember from the job are all of the [easily lost] small metal clips for the blower motor box, and doing a bit of finessing to ensure that the regulator wires are routed correctly as the originals, and fitting the regulator and new blower motor into place taking a bit of jiggering. IIRC I had to remove the blower motor bracket (that it rests on/into) to get at the regulator. But it all seemed to come together OK. I would put this job at about a 3 on the 1-10 difficulty scale. It's more tedium than anything else.

    It must be a common issue (blower and/or regulator failure), because I see the blower motor boxes torn open and the motor+regulators removed on at least 50% of the W124s I see in the wrecking yards here in Houston.

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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    You were by no means exaggerating on how difficult it was to remove and install [the regulator and heat sink].

    I'm normally a patient, happy, smiling man; the photo of me holding the dead porcupine says it all. I wanted to drive over it repeatedly.

    Just glad it's finished.


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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    Quote Originally Posted by gerryvz View Post
    Dave, while I've only worked on later (facelift) W124 blowers, and can't speak for Makemeister with his pre-facelift car, I don't recall the blower motor and regulator replacement (particularly regulator) being all that big of a deal, nor particularly tough to do.
    The 94-95 models with dust filter have a COMPLETELY different design for the heat sink. You don't even need to remove the 94-95 heat sink, the small regulator sits on top and can be unscrewed easily while the heat sink remains in the car. 100x easier than the early cars. I would not even bother removing the heat sink on a 94-95, just clean the surfaces and apply fresh thermal compound. More photos at this link.


    Quote Originally Posted by gerryvz View Post
    What I do remember from the job are all of the [easily lost] small metal clips for the blower motor box, and doing a bit of finessing to ensure that the regulator wires are routed correctly as the originals, and fitting the regulator and new blower motor into place taking a bit of jiggering. IIRC I had to remove the blower motor bracket (that it rests on/into) to get at the regulator. But it all seemed to come together OK. I would put this job at about a 3 on the 1-10 difficulty scale. It's more tedium than anything else.
    All correct for the 94-95 models.


    Quote Originally Posted by gerryvz View Post
    It must be a common issue (blower and/or regulator failure), because I see the blower motor boxes torn open and the motor+regulators removed on at least 50% of the W124s I see in the wrecking yards here in Houston.
    It is a pretty common failure. Supposedly new blower motors can kill old regulators which is why many shops insist on replacing both at the same time, to avoid customers coming back a few months later with the "new motor not working".

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  21. #12

    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    Hey Guys: I think I posted the plastic screw part number previously for someone but happy to do it again: 124 821 00 73. List is $7.75, discount price $5.81.

    Regards,

    Peter Weissman

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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    Quote Originally Posted by geraniumtr View Post
    Hey Guys: I think I posted the plastic screw part number previously for someone but happy to do it again: 124 821 00 73. List is $7.75, discount price $5.81.

    Regards,

    Peter Weissman
    Looks like you got the "flower screw" indeed! EPC diagram attached. Thanks for the update !!
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  25. #14
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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    Quote Originally Posted by geraniumtr View Post
    Hey Guys: I think I posted the plastic screw part number previously for someone but happy to do it again: 124 821 00 73. List is $7.75, discount price $5.81.

    Regards,

    Peter Weissman
    Thank you! I'll include one in my next parts order from Naperville. Although I can't imagine what could possibly be replaced on my car at this point.


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    Re: HOW-TO: Replace W124 Blower Motor & Regulator

    Quote Originally Posted by makemann View Post
    Thank you! I'll include one in my next parts order from Naperville. Although I can't imagine what could possibly be replaced on my car at this point.
    Get two of them (there are two required) and replace BOTH of them. Any 25-year-old plastic that is remaining around the rear of the engine & in the engine compartment, is going to be thoroughly heat-soaked and brittle as hell. This is a cheap part.

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