justanothernoob

on my 2004 B6 Audi S4 Avant I've noticed that my aircon stops working in the dark.

This happens whether I have the aircon set to auto or even if I've manually set the fan speed and temperature.

Some examples:

1. at night the aircon will not come on - unless I hit the ECON button which will then blow some air through but it doesn't feel like it's aircon
2. if I drive into a tunnel the aircon will stop blowing but will start again as soon as I come out of the tunnel
3. similarly if I drive into a covered carpark
4. even if I drive under a flyover / bridge the aircon will stop blowing for the split second it takes me to pass under the bridge

It's almost as if there's a UV or light sensor somewhere?

(Incidentally - there IS a little box attached to the top of the windscreen by the rear-view mirror. Anyone know what that is?)

Any thoughts?

justanothernoob

WOW - nobody has any ideas? Really? I thought you were all-knowing wizards with pointy hats, cauldrons and mantras! Surely someone has a few ideas up their bellowing wizardy-cloak-sleeves?