can anyone help please, this noise is doing my head in. I have so many people trying to diagnose the problem. I have an X reg Xantia and the noise cuts in when the engine warms up and is on all the time over the engine sound. I have had the Air con re gassed and checked. I have taken it to many Citroen garages but either it does not happen when they have the car or they haven't got a clue. HELP