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2010 Mercedes c300 Radiator fan problem

Radiator fan starts running 5 seconds after the car is started
It doesn't matter if the engine is hot or cold the same thing happens, AC is off.
the coolant temperature sensor shows proper temperature of the engine.
AC is charged to the proper value.
there are no errors in the car.
can anyone guide me in the right direction as to fix this problem?
Thanks given by:
check and compare actual value temp on ecu and ac
Thanks given by: koziolek
You have a problem with the engine control module. It needs to be replaced or repaired.
Thanks given by: leminhautotek , koziolek
Do do you know what need to be replace in ECM?

I just checked refrigerant pressure when engine cold in a morning 12.9bar
when start engine 14.8 to 15.4 bar on ruining AC and engine temperature at that pressure was 41C
Thanks given by:
No. I have never repaired one.... only replaced them.
Thanks given by:
If disconnect sensor fan works full speed
and pressure shows some high number like 699

at this moment engine is off
coolant temp-42c
refrigerant pressure 14 bar
one value does not look ok for me
N70b1 Interior temperature sensor with integrated fan shows steady 98.99C
this does not change
but is this can be my problem?
Thanks given by:
Isn't there a bulletin about differences in outside temp/intake air temp to coolant temp will cause this.. update engine control unit software fixes it... if I remember correctly...

Remember the THANKS and + buttons if this helps you... It just makes me feel good
Thanks given by: koziolek
I had the same issue on a 2012 C250 CGi..

The car had been in a front smash before and was repaired poorly..

Long story short, the A/C pressure sensor was missing. bought one (same on BMW) and plugged it in. Also outside temp sensor was missing and a replacement had to be fitted.

Still didnt fix the problem.

But in StarDAS/Xentry there is an option in control unit adaptions for the ECU. There you will find the option to code the temperature at which the fan should kick in. Do that coding!

Once we did that , the fan is went back to working like normal..

(P.S. we did not even re-gas the AC yet, its completely empty)

Hope this helps. all the best!
Thanks given by:

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