Vibrations Issue: Troubleshooting Near 2000 RPM.

Hello, I'm having the following problem with my ALH:
Strong vibrations between 1900 RPM and 2000 RPM.
I initially suspected the problem was related to the belt drive, so today I removed the belt from the pulley.
If the belt comes off, the power steering pump, air conditioning compressor, alternator, tensioner pulley, and idler pulley will all stop working. That's it!
If I put the belt back on and only remove the one that goes to the alternator (meaning everything except the alternator and tensioner pulley is still driven), the noise returns, but the vibrations are less intense.
In my opinion, the cause is likely either the power steering pump, the air conditioning compressor, or the tensioner pulley.
Nowhere on these parts did I notice anything unusual.
Komme jetzt nicht weiter. Was würdet ihr machen ? Does anyone have any ideas?
Thank you!

I've continued experimenting.
I can only imagine that it's the air conditioning compressor.
I never use the air conditioning anyway. Does anyone have any ideas on how I can modify it so that my alternator works even without that stupid compressor? How does the alternator work in Golf IV models that don't have air conditioning?

Okay, another step forward.
Okay, so here's the thing: Removing the V-ribbed belt does indeed reduce (almost completely) the vibrations, but it apparently doesn't fix the underlying cause.
I still have a mechanical grinding noise that occurs precisely at 1850 RPM – you can sometimes hear it at other speeds as well, but much quieter.
I suspect the origin is on the belt side, but there isn't much left to see.
I removed the timing belt cover, but I can't see anything unusual. Could it be that a bearing in one of the pulleys is defective? However, wouldn't a ribbed belt transfer vibrations to the entire engine if a pulley bearing was bad?
Could it be the pulley? Probably not, right? Why would it make noise if the belt is off...? Where else could the problem be? Could it be the crankshaft? Again, probably not. I've already driven 400 km without any problems with this issue. Please help me!

What kind of car do you actually have?
Check if the alternator's clutch is stuck! If your car has one.
When defective, it produces loud belt noises. It starts to make a noticeable fluttering sound.