First, as far as I know, there is no fan that pressurizes the brake system. If your pressure reservoir for your ABS is bad, that's totally different. BUT from the sounds of what your dealer told you, there's also nothing in the ABS with bearings that go bad. SO I think you're "being taken" or they aren't completely describing and therefore you are understandably misunderstanding them.

The secondary air pump is an emissions part and runs at the times you are describing. It can be removed and you'll need to add in an 'oxygen sensor simulator' to fool the computer to think that the pump is blowing air through there. You can do a search for that on your favorite search engine. I used a $7 one off of ebay but there are very nice ones sold for about $40. It's basically a resistor that makes the rear sensor appear to be reading a leaner mixture than the front sensor.

Also, the pump is a DIY job if you wanted to tackle it. Pumps from Audi, VW and BMW will fit and can be found for about $150 or less. I didn't want to replace mine for a few reasons (cost was the main one), but many will encourage you to replace yours even though it runs for only a minute or two each day.

Anyway, if you want more info on eliminating it, you can contact me directly or do some searches on the VW sites about removing this pump. FYI, I left my valve in, just took the hose off. You'll understand this once you do your own. Have fun!

Mike