Auxiliary fans W202 C43AMG

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DRBC43AMG

MB Enthusiast
Joined
Mar 15, 2010
Messages
1,118
Location
Switzerland, Locarno (TI)
Car
2013 C63 AMG coupe "T-Rex", 1999 C43 AMG saloon "Grandma" (sold), Ultima Sports Can-Am (sold)
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?
 
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
 
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.
 
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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...
 

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