5k Alternator (Was 5k Battery)

["KEN" <kkaregeannes@hayes.com>]

Went and had my battery and alternator checked by AutoZone after I was having
problems with the battery draining to the point the car wouldn't start. The
battery is an 84 mo. that is only about 18 months old. This after everyone
that replied to my "5k Battery" query seemed to agree that 5k's don't eat
batterys regularly.

Both checked out okay. They have this neat device that attached to the battery
posts and checked both alt and battery at the same time. An interesting phenom
showed up and I'd like to get some input observations on it.
The alt showed 12.5 volts at idle (no auxiliary electrics turned on.) Then I 
switched on the A/C blower. Wow! Voltage dropped to 8.5 volts, then recovered
but fluctuated between 10.5 and 12.5 volts. The AutoZone guy said my alternator was
okay, but it wasn't able to charge the battery when I was doing alot of stop
and go driving. I find this hard to believe since I never had this problem
when I lived in Tucson AZ and had to deal with serious heat. 

My guess is the alternator is not up to the task anymore and needs a rebuild
or to be replaced. Or else the battery is just shot and can't hold a charge
Since I can't find a rebuilder to do it for less than $100+ I'm hoping its the
battery. Since I've now discovered my steering rack is leaking, I'd love to
be able to solve this cheaply. Oh yeah, I didn't drive the car for about 10 days
and when I went to start it, it would barely turnover. Could this indicate a
short?

Any insight/advice will be greatly appreciated.

-ken-