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Thread: W124 Blower not Working

  1. #1

    W124 Blower not Working

    Folks: Blower stopped working this AM. Here's what I know: Blower motor is about 6 years old, regulator ( factory part) about 3 years old. The strip fuse is new as I had one on the shelf and installed it. The PBU is likely the original.
    I had one episode last week when blower stopped but started working again within a few minutes. Otherwise no problems at all. FWIW I do hear the flaps moving as I push the various air flow buttons.
    Any help appreciated.

    Regards,

    Peter W.

  2. #2
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    Re: W124 Blower not Working

    Sounds to me like a bad regulator. Re-check your fuse before anything, though.

  3. #3
    Senior Member Allgonquin's Avatar
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    Re: W124 Blower not Working

    Just double check the strip fuse. They can look perfect but have failed.
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    Re: W124 Blower not Working

    +3 on the fuse, you need to remove the fuse to inspect - visual isn't enough. Another long shot is wiggling the ignition key, turning it slightly back towards off (without actually turning off the engine).

    Since the regulator AND fan are both relatively new, and very unlikely to have died, this will require more advanced troubleshooting techniques. How handy are you with a VOM?

    Also - when the blower motor stops, is it completely off, zero speed?


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    E500E Guru nocfn's Avatar
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    Re: W124 Blower not Working

    voltage off the PBU on firewall (pita behind the check valves). I also agree on "possible" worn ignition switch as a source of gremlins....
    1994 E500
    249/275 - 8F19 or 8F32 or 8320

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

  6. #6

    Re: W124 Blower not Working

    Thanks for the suggestions. Update: HVAC system worked normally on the way home last night but this morning it did not work. Yes Dave , when blower quits -- it's completely off. I will try wiggling the key and report back.
    I do have a multi- meter but am challenged in this area.

    Peter W.

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  8. #7

    Re: W124 Blower not Working

    Folks: The strip fuse shows continuity. I did the wiggle the key test but the blower remained off. Frustrating for me as the car has been running great and it's my DD.

    Regards,

    Peter W.

  9. #8
    E500E Guru nocfn's Avatar
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    Re: W124 Blower not Working

    How many volts coming off the firewall wires with fan on high?
    1994 E500
    249/275 - 8F19 or 8F32 or 8320

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

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    W124 Blower not Working

    Regulator or the pushbutton unit would be the only things controlling voltage to the fan if the fuse is OK. Unlikely the PBU would fail. My guess is the regulator.

    If you have a pre facelift cR you can get a Behr (OEM) unit for $150 which is much less than MB charges for same. Facelift cars ... it’s MB or KAE, questionable quality aftermarket.


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  11. #10
    E500E Guru nocfn's Avatar
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    Re: W124 Blower not Working

    Having replaced my regulator, all the voltages were normal at the firewall and at the Strip fuse. GVZ most likely right - new regulator.
    1994 E500
    249/275 - 8F19 or 8F32 or 8320

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

  12. #11

    Re: W124 Blower not Working

    Thanks again for the help. I ordered a new regulator this morning from my local foreign parts store. Picking it up tomorrow. My car is a face lift E320. A little under $200 for a Kaehler (KAE) which I specified. The factory part is quite a bit more even with the discount I normally get from the dealer.
    Will I need to add some additional thermal paste ?

    Regards,

    Peter W.

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    Re: W124 Blower not Working

    Peter, the good news is, for a facelift car you can unbolt the regulator from the heat sink to swap it out... no need to wrestle the entire heat sink in & out which is a real pain. A dab a fresh thermal grease would be nice but if not available, scrape from the old one if you need a bit more during installation. Don't forget to test the blower before re-assembling everything - if it still is dead, remove the wires and connect +12v directly to the motor, to confirm the motor is good (I'm sure it is).


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  15. #13

    Re: W124 Blower not Working

    Dave, Gerry, Nocfn: Well I'm back in business... installed new regulator this evening and blower is working as it should. Thanks for your assistance. I've changed dust filters numerous times and had the wiper out so it was easy for me to get to the blower case. After that it was a learning experience. Yes Dave the old Bosch regulator that was in there unscrews from the heat sink... but the new K.A.E. does not! I was afraid the plastic housing would break but it didn't and I wrestled it in.
    I also checked the blower using the battery and some leads. As you suspected it worked fine.
    Thanks again guys.


    Regards,

    Peter W.

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    gsxr (02-09-2018)

  17. #14
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    Re: W124 Blower not Working

    Glad to hear it's fixed, Peter! But... the old regulator was an OE/dealer part and it failed in 3 years?


  18. #15

    Re: W124 Blower not Working

    That's correct Dave. I have to pull the invoice but definitely not older than 3 years and I had the dealer install it. One thing I noticed was some water sitting in the blower case and the dust filters were wet. A year or so ago I replaced the one piece weather stripping along the bottom of the windshield because it wouldn't stay put. The new one is better but the sealing around the wiper head has been a problem. Water must be dripping onto the filters and getting in the case ?
    My windshield was replaced with factory about 5 years ago---I just don't think the plastic track that mates to the weather stripping is very good. I'm thinking about using some trim adhesive. What do you think?

    Regards,

    Peter W.

  19. #16
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    Re: W124 Blower not Working

    Quote Originally Posted by geraniumtr View Post
    That's correct Dave. I have to pull the invoice but definitely not older than 3 years and I had the dealer install it.
    That is seriously disappointing. The original lasts 23 years and the replacement dies in 3?


    Quote Originally Posted by geraniumtr View Post
    One thing I noticed was some water sitting in the blower case and the dust filters were wet. A year or so ago I replaced the one piece weather stripping along the bottom of the windshield because it wouldn't stay put. The new one is better but the sealing around the wiper head has been a problem. Water must be dripping onto the filters and getting in the case ?
    The filters should never be wet... sounds like something isn't seated properly around the center portion, under the wiper gearhead. Water is supposed to get into the case via the air inlet grilles, and drain out via the 2 foam tubes which drop the water on to the transmission. But when everything is working properly, the filters remain dry.


    Quote Originally Posted by geraniumtr View Post
    My windshield was replaced with factory about 5 years ago---I just don't think the plastic track that mates to the weather stripping is very good. I'm thinking about using some trim adhesive. What do you think?
    The plastic channel on the bottom of the windshield tends to spread apart and not retain the rubber gasket very well. A brand new one should be fine, and if yours is only 5 years old it should still be good. However, it's tricky to get the rubber gasket fully seated across the base of the glass. If it's seating at first and then popping out, and the channel & rubber both appear intact, you could try using some urethane adhesive along the upper lip to "glue" it to the glass. I think a lot of cheapo windshield installers do this on facelift cars when they order the wrong glass (without the channel) and have no other way to make the rubbers stay in place.


  20. #17
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    Re: W124 Blower not Working

    Indeed, even the aftermarket KAE regulators for the facelift cars generally last more than three years. Glad to hear you found the issue. Generally if it’s not the fuse, and things are getting no power, then it’s the regulator. Much rarer for the PBU and the electric squirrel cage motor to go out.


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  21. #18
    E500E Guru nocfn's Avatar
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    Re: W124 Blower not Working

    Good news, and getting that mb heatnsink was hard for me, the. The kae didnt bolt into it either. But, satisfied both of those are now done
    1994 E500
    249/275 - 8F19 or 8F32 or 8320

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

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