I would like to thank to both, MB STARS and BENZMAC, for their help. You were both correct, my fuse on the fan relay was blown.
I have replaced it with new one of 15 Amps for now, but I will put a 20 Amps ASAP.
One more time many thanks for saving me a lot of time and money. The MB dealer was going to charge me around $ 70 , just to talk to me.
They woul not tell me anything unles I took it to them for diagnosys. THANK YOU !!!
Keep up the good work!