Strange alarm fault

I have a strange alarm fault developed on my audi a4 (2001).

Once the outside air temperature gets down to 45 degrees F (generally in the
middle of the night) the audible alarm goes off (the lights do not flash).
This continues for a couple of minutes and then generally re-occurs about an
hour later.

I have checked all other aspects of the general alarm system (motion and tow
away) and everything functions correctly - ie sound and flashing lights. I
am assuming that my problem may be with a faulty frost sensor.

Has anyone on the NG had a similar problem and can anyone tell me where the
frost sensor is located.

Mike

I have a similar problem as Mike (13 Nov 04)developed on my Audi A4 (2001).
At night with similar air temperature my alarm goes off but the lights also
flash. It is then difficult to unlock the car with the key fob and usually
I have to resort to using the physical key to turn it off and on. After
this the locks continue to click for a few minutes. Does anybody know how
to resolve this?
Thanks, Pete