On my 99 s3 I have had a weird fault with my air con!
When i put it on the air con on it does not always work. I can drive home from work and nothing (cold) i open bonnet no fans and compressor does not kick in and out when i press the button on the unit.
I can leave the car a while go out start it turn on air can hey presto the fans come on and the compressor kicks in all fine!?? And perfect cold air!??
I had it cleaned and re gassed last year and it didn't help as it did not come on after i had had it gassed
drove a short while and it came on.
Is there anything worth checking and cleaning etc wires, fuses relays fan swithches....... Head doer.com