I am not a ferret expert by any means, but I do have five years of
experience of living and traveling in Central America with my two
ferrets.
 
First of all, Shelley, don't wait until this happens again before you
take action against the heat.  Heat can be deadly to ferrets, and, if
they are already panting, you have a life threatening situation.
 
A fan by itself probably doesn't do a whole lot of good because it
doesn't significantly alter the temperature of the air.  Fans cool us
because we can perspire, but ferrets can't do that.  If you combine a
damp towel over part of the cage (not where it can drip on the ferrets)
with the fan aimed toward the towel, not the ferrets, you can lower the
temperature a bit.  You can also put frozen water bottles in a sock and
put them in the ferret cage.  There are other similar ways, but they all
depend upon someone being in the vicinity every couple of hours to make
changes if needed.
 
It might also be a good idea to buy a portable thermometer to put near
the cage or wherever they hang out on hot days.  That way you don't have
to guess whether or not the heat is creeping up.  My ferrets have done
fine as long as I don't let the air temperature get above 80 degrees.
Perhaps someone more knowledgeable than me can speak to this point with
a little more authority.
 
I live in a house similar to yours where it can get very hot in the
summer.  I bought a window air conditioner from Sears for $100.  It
cools the room to a temperature where I feel very comfortable leaving the
fuzzies on their own for a number of hours.  Actually, one of these hot
nights, I might just camp out in their room!
 
Good luck with your fuzzies,
Shirley
[Posted in FML issue 4176]