"Annoying Sound in a 1997 Mercedes Benz C class C230"

1997 Mercedes Benz C class C230

This is a 1997 C230 Mercedes Benz C-class (not compressor). The generator is the sound each time the engine. Just do it once a day, morning (when the engine is cold). The last note at least one minute at a time. Can someone tell me why the generator does that sound? And if you change the alternator, the sound will stop?

Answer: The alternator shouldn’t be making any sound at all, are you sure it isn’t the belt?
If it’s not the belt, then you’ve got a bearing going out in the alternator and it’s time to replace it.
One way to tell for sure if it is the alternator is to get a long screwdriver, with the motor running, when it’s making the noise, be careful not to get near the belt, put the tip of the screwdriver on the alternator and put your ear to the other end of the screwdriver. It acts like a stethoscope. you can pin point better where the sound is coming from. Also, don’t touch the screwdriver to any of the terminals on the back of the alternator. Be very careful when doing this, but it could help you better find where the problem is.