My A6 le mans has a problem with the ac. For the second time it wont go cold. The first time it happened the car had been standing for a month. This time it stopped working after i pulled all of the fuses out and replaced them looking for a light fuse. I think it may be a computer problem as all the ac control lights are now on permanently. It blows hot air but not cold.

 

I had the same issue, but the ac economy button would stay on and the compressor was turning. I replace the module and the used module was bad. I took it to a repair shop who said the clutch was bad. He didn't even test my system. I wasn't buying it and found another mechanic that works on Audi. He did a AC eval and found my high pressure switch was bad and I had no freon. So he replace the switch and put dye in my system and told me to bring it back once it goes hot. He told me the ac lights will stay on if there is some type of problem with the ac. I have a 2002 audi a6, He also said that the audi will have small leaks that they can never find. And that every couple of years you might need to recharge the systems. So far ac is holding up after a month.