[joseph alison]

I just want to share my experience with the issue i had with the the Fan motor with integrated control module (attached picture). This fan is installed on the cooling  system of a Mercedes C250 , 2013 Engine c ode 651-911.
The Fan's motor is connected through 4 wires: Two heavy gauges wires, the positive and the negative (the positive directly from the battery through a 100 amps fuse and the negative to the chassis). Another wire connected to a fused  (22 amps) from the front SAM and the command wire connected directly to the ECU.

Symptoms:
-Engine running cold and A/C turned on: the fan starts.
-Engine running cold then removing the connector on the Coolant Temperature sensor (CTS), the engine starts with 100% duty (fail safe situation).

-Engine standstill then activating the Fan through жеитяу or Vёdїамо, the fan starts and responds to the duty cycle percentage.

-Engine hot (90 DegC) and turning the A/C on, the fan does not starts.
-Engine hot then removing the connector from the CTS, the fan does not start.
-Engine hot then trying to activate the fan through жеитяу or Vёdїамо, the fan does not start.
-Engine hot and measuring the signal on the command wire revealed that the ECU was attempting to wake up the fan motor (7.5 V for one second then wait 10 seconds and repeat the cycle).
The fuses are OK. Wires continuity and resi5тдnce are OK. The engine ECU was re-flashed. The integrated control module in the Fan motor was reset through Vёdїамо.
When the engine was left to coll down, the Fan motor answers all commands.

Conclusion: it was apparent that the issue was heat related  and i strongly suspected an issue with the Integrated control module on the Fan's motor.
I removed the fan assembly, removed the motor from the fan assembly,  removed the plastic cover on top of the module to uncover the electronics for inspection: I discovered a cold solder joint on one leg of the power Mosfet or triac. Cleaned the area and soldered the defective area using good quality solder and flux. I then put back the plastic cover on top of the electronics for waterproofing using high temperature silicone. re-installed the fan assembly and did a test drive, the fan is not working as it should engine hot or cold. This saved me  a lot of money.
So, just in case you experience something similar, don't hesitate to inspect the electronics on the integrated control module of you cooling water fan.