Radiator fan on continually!

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therogg

New Member
Joined
Apr 10, 2012
Messages
17
Car
c220 cdi coupe sport
I have just had the swirl flaps removed from my clk 270 cdi year 2004 , now the rad fan is in contually, there’s is no kick down , fault shows ams , which is new , egr problem and boost sensor , the garage still cannot dint the fault , I am begging to think the ecu is at fault . I had a full diagnostic before the swirl flap mod , the engine only done 105 k miles and it’s in great condition , now apart from this . HELP please .
 
Check the battery, had the fan running all the time on my sons car and it was the battery, not enough power to operate the relays properly.
 
Not sure of the temperature setup on you car. Sometimes the fan is on a separate temp sensor to the ECU and in-dash display. The temperature sensor that controls the fans might be duff. Alternatively, the control electronics that are often around the back of the fan hub might have go damaged, wet, and this could be causing the fan to run.

If you interrogate the coolant temperature sensors using fault diagnostic software to read live data, you should be able to see if one of the sensors is playing up (it will give a silly reading I would guess if it is the sensor, otherwise if they look normal then look elsewhere for the fault).

Do you have any STAR errors listed when it is scanned for errors?
 
On some models, the Radiator fan controller has a CAN-bus connection to the Engine management system.
If that connection is lost, the Radiator fan operates at its maximum speed in order to protect the engine.

I guess that if the temperature sensor is shorted (or open) the same thing could happen.

Check all connections for corrosion, loose elements etc. And if no obvious fault is found, have the car
scanned by Xentry.
 

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