Hey guys I have had a bit of a search and don't think anyone has had this problem. I put my climate control on and no worries, I press the AC button (compressor) and works fine until I turn left in the car and the rattling or rubbing sound starts and doesn't stopped until I turn off the AC compressor.

My car is a A4 1997 1.8?

Also today for some reason some strange dust came out the vents when I turned on the AC?

Any thoughts

 

I would guess that the plastic fan is loose and is rubbing against the housing. I would guess that the dust may be little pices of plastic dust as the two wear against each other.

If it is the fan, then it would continue if you turn the heat on (ie the fan is running, but the AC is off). Double check if the noise stops when the AC is turned off but you turn the heat up.

Otherwise it would likely be the AC compressor and I have no good explaination for the dust. My car puts out dust if I haven't changed the the airflow direction for a long time. I suspect it is dust settling in the system and when the internal air direction valves are changed, some gets blown out.