I was in line at an idle at the outside bank teller window for too long
today and I heard this loud fan come on.  I looked at my temperature gauge
and it was up a little bit over where it usually is but not up to the line
that I guess indicates that "you in deep doo-doo now".  Anyway, the fan
came on for about 10 seconds or so then shut off and did this again about 2
minutes apart about 3 more times.  I left there and drove about 1/2 mile to
a store, spent about 10 minutes in the store and when I came out the was a
pretty steady stream of antifreeze  coming out of my engine area.  I opened
the license plate hatch and checked the bottle and couldn't make out where
the level was so I opened it.  The antifreeze was almost up to the top of
the bottle (or tank).  After waiting a minute or so, the leaking stopped
and the level in the bottle went back down to the line where it should be. 
I drove home from there (about 4 miles) and watched the gauge all the way. 
It was in the normal area and the van ran fine.  Do I need to worry about
this?  Does this fan just come on when the engine is overheating?  How do
you keep from loosing the coolant? Why have I never heard this fan
before????
Thanks for wisdom in advance
Wendy

'85 Westy,   "S-CAPE"