So you'll be pleased to know that the bleach solution worked for the air conditioner. Turns out it was sludge and algae in the pipes after all, and no $10,000 system was needed.
It's been running all day...no water AT ALL ANYWHERE, and the air is toasty cold and smells like a freshly cleaned bathroom!
YAY!!!
The Husband's new name is Mr. Fixthings. Although he attributes his success to my lightning-quick googling, which of course is thanks to my library education.
THANKS MASTERS DEGREE!!!