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Discussion Starter #1
400e fan always on even when ignition is off, anyone know where the sensor and relay is? Thanks!
 

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W124 Moderator
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Might help if:

You filled out your profile.
HVAC fan?
Aux electric fans in front of the radiator?

There is no electric fan inside the control module "coffin" box.

Jayare
 

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Discussion Starter #3
It is a small ventilation fan for the computers and is directly behind it. It pulls cool air around the computers to prevent them overheating, it is about 4 inches tall and 3 in diameter.
 

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The fan for the "coffin" box or computer is the blower motor itself, thats what jayare is getting at. So we are pretty sure its not that.

Good Luck.
 

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Cole

Mercedes didn't put a cooling fan on the back side of the coffin box to draw air around all the control modules. There are a total of 4 electric fans on a 400E. Under the passenger side dash is a "sampler motor" used to draw air from the interior to control the auto fan speed for the HVAC system. There is the HVAC fan that is under the hood, dead center under the wiper assembly. Obviously blows air from the HVAC vents. Two electric aux fans just behind your grill.

Any other fans installed were done by some previous owner.

Jayare
 

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Discussion Starter #6
If you look directly behind your box by te heater valve it is right next to it, I have 2 400e cars and they both have it, same part same mercedes logo on it, could you look at your car and double check for me? Thank you very kindly. Cole.
 

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W124 Moderator
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EPC does not show any fans. I don't have my 400E with me at the moment, so I'm not able to check it. What is the part # on the fan you are concerned about? Just recently, I replaced my lower engine harness and obviously was all in behind the coffin box. No fans.

Maybe this is something that is in non-US cars. Where are you located?

Jayare

Edit - I must apologise. The part in question is PN 124 830 0908 and is called a module box ventilation blower. Found it on EPC located in the heat/ventilation section. I'll see what I can find on the electrical diagrams.
 

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Discussion Starter #9
Thank you so much for finding that, it looks like we both learned something new, I learned the diagrams and now you know that you have a fifth fan :D Thanks!
 
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