Auxiliary fans W202 C43AMG

Discussion in 'Engine' started by DRBC43AMG, Jul 2, 2015.

  1. DRBC43AMG

    DRBC43AMG Hardcore MB Enthusiast

    Messages:
    1,079
    Joined:
    Mar 15, 2010
    Location:
    Switzerland, Sion (VS), the canton of mountains, w
    Car:
    99' C43 AMG "T Rex", 00' Renault Twingo1, Ultima Sports Can-Am
    Not sure is this is the right place for the query, but here goes anyway.

    Now that we have started a big heat wave which should continue over the next days, I noticed that only one auxiliary fan up front is in operation with the A/C engaged (necessary these summer days). The A/C was topped up a couple of weeks ago and the system blows nice cold air inside.

    When does the second fan kick in? Is it for the A/C or as an extra fan should the engine get very hot (not my problem) even with the viscous fan engaged?
     
  2. hotrodder

    hotrodder Hardcore MB Enthusiast

    Messages:
    845
    Joined:
    Sep 28, 2008
    Location:
    south east
    Car:
    '93 320te
    Unless MB changed things (i'm more familiar with the 124) both fans should run at the same time. They're variable speed and switched according to both A/C pressure & coolant temp, switching points here... http://www.w124performance.com/service/w124CD1/Program/Engine/104/20-0020.pdf

    The fan that wasn't running... does it turn freely & smoothly by hand? One of them is semi dead on s124 in that it only comes to life if given a helping hand by flicking the hub in direction of rotation
     
  3. andy27168

    andy27168 Hardcore MB Enthusiast

    Messages:
    4,364
    Joined:
    Nov 27, 2004
    Location:
    Southampton
    Car:
    1997 C230K, 1999 C43/55 AMG
    As above both the Aux fans in front of the radiator should run at the same time, their speed varies according to the pressure/temp of the refrigerant. The fan speed is controlled by a control unit fitted inside the front of the passenger side wheel arch, these variable speed controllers can go as well, though I don't believe this unit failing would stop one of the fans from working. It is more likely the fan seized or just kaput.
    They plug into the loom under the bonnet on the right hand side (looking at the car from the front) of the radiator assembly I would put 12V directly on the duff fan just to confirm it is U/S, and not a wiring issue.
    They are quite expensive from MB but I believe you can get replacement fans on Amazon, there is a German company on their that do them, a guy on the other forum recently had to replace one on his 202 and he reckoned it was a direct replacement and the price was substantially cheaper than MB.
     
    Last edited: Jul 2, 2015
  4. OP
    OP
    DRBC43AMG

    DRBC43AMG Hardcore MB Enthusiast

    Messages:
    1,079
    Joined:
    Mar 15, 2010
    Location:
    Switzerland, Sion (VS), the canton of mountains, w
    Car:
    99' C43 AMG "T Rex", 00' Renault Twingo1, Ultima Sports Can-Am
    Thanks for the input. The duff fan is not seized and I'll try to connect direct to 12v and see what happens.
    I was reading 39c in the shade on my terrace this afternoon and the forecast is for higher temps over the next days. I guess having all fans working will be good practice in order to avoid heat problems...
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.