wierd noise

my 99 disco s2 makes a rather strange, quiet noise while running.  i only hear it when i pull up to stop and it sounds as if there is some sort of electrial motor that comes on for a quick 3 seconds or so, then it is quiet again. the noise is not very noticeable, but i am always listening for anything unusual. any info would help... oh and btw, it sounds like it is behind my glove box, or by it. if i open my glove box i can hear it better.

This is just a guess, seeing as how I've got a Range, not a disco, but it could be the load leveler if Discos are so equipped.  It won't kick in while moving, but at the stop it might attempt to level itself.  Could be a height sensor going bad causing it to randomly start to 'level'.

yea, that sounds like it could be it. do you know where those hieght sensors are located and where the load leveler is located? is it something i need to be worried about? thanks for the response! much appreciated...

That is most likely your secondary air pump if you have secondary air, as an emission device.