Strange noise

[TomRS]

@TomRS - hope so you are right...but the noise is getting louder when I turn on the A/C :/

There's more strain on the system with A/C compressor engaged as its now turning a compressor rather than just spinning the idler pulley... A/C pumps arent known for going bad but doesnt mean it isnt that.
Needs checking throughly

[Audi-RS6-R]

Yeah - I see...it has to be checked part on part

[Quattro_RS6]

If you want to be sure, just take your car to the workshop and dismantle the alternator belt, then you are able to turn all pulleys, alternator and AC compressor by hand and listen for bad bearings. I think you can reach the alternator from the underside of the engine, if not you need to dismantle the front end and pull it out in "service position".

General note:

AC compressor - can be dismantled without removing engine, but it's easily 15-20 hours of labour.
Alternator - same as above, but is easier to dismantle
PS pump - gearbox needs to be dismantled because the bolts holding the pump is located inside the bellhousing. Oilpump also needs to be removed to get access, as the PS pump sits above the oilpump.
Oilpump - can be removed from underside of car, without removing AC compressor, but is a 20h job. (Have just recently done this myself)

[Audi-RS6-R]

Thank you Quattro_RS6 for all this information - I will keep it in mind...

[TomRS]

If you want to be sure, just take your car to the workshop and dismantle the alternator belt, then you are able to turn all pulleys, alternator and AC compressor by hand and listen for bad bearings. I think you can reach the alternator from the underside of the engine, if not you need to dismantle the front end and pull it out in "service position".

General note:

AC compressor - can be dismantled without removing engine, but it's easily 15-20 hours of labour.
Alternator - same as above, but is easier to dismantle
PS pump - gearbox needs to be dismantled because the bolts holding the pump is located inside the bellhousing. Oilpump also needs to be removed to get access, as the PS pump sits above the oilpump.
Oilpump - can be removed from underside of car, without removing AC compressor, but is a 20h job. (Have just recently done this myself)

Brutal... P/S pump can stay whining there's no way i'll be changing that any time soon!