Loud fan when turning car on w205 C class c250d

[Mohammed919]

I need help guys

When i start my car after a few seconds the fan kicks in but it is very loud. When i drive and come to a start/stop the loud fam noise shuts off. Also the fan always comes on loud whenever i turn my AC on.

Any idea what the problem could be ? Not sure if its normal as i did not have this problem before

 

[Kurda]

Your car might have started DPF registration process, if it is, doing around a 40 mile run and keeping the speed around 70mph should let the process complete.
It is normal for your fan to come on when you switch on the air conditioner (cooling) as this makes the engine work harder and add another heat source for the system to cool down.