My son's 2000 A6 4.2 auxiliary fan stopped working and I had someone look at he fuses and they said there were none blown. The car doesn't run hot the temp. gauge goes past to the next line just past the half way mark. We also did some sort of bypass to see if the fan did work and it does. We also replaced a switch that connected to the bottom of the radiator and it still didn't work. An if that isn't bad enough the AC wont charge nor does the compressor switch on all of this came about around the same time. Please help me find a resolution to this problem
Frank Binns

 

Its probably a bad A/C high pressure switch or something along those lines. It gets power from this switch. You need to buy the vag com software and a cable to diagnose the A/C system www.ross-tech.com. It will most likely have a fault code in the A/C electronics pointing you in the right direction.