Hello, hope someone has had this problem, as it could get expensive otherwise! My wifes A3 has been sitting on the drive for about six weeks now, as it is for sale and there has been no interest. I started it yesterday and there was a loud 'clicking' noise every couple of seconds, which was coming from the air con compressor clutch cutting in and out, (on for about half a second, off for about two seconds). It does this continuously unless I turn the air con off. I had the gas checked and it is spot on, but the chap told me that you can't run a diagnostic on the climate control, and that it could be 'anything'. As it is for sale I don't want to start spending a fortune, but it would be good to sort it out as the car will be worth next to nothing with such an annoying fault on it. The Climate control still provides cold air, by the way. Hope someone can point me in the right direction, cheers, John.