This wasn't happening before the mechanic in St. Louis took a look. We told him about the horrible AC noise, he found a chewed-up AC belt, and said "Aha, that's the problem". Only replaced the belt.

Well, the car still made the noise, and I didn't get it until after hours on Friday (we had to leave Saturday). Obviously the REAL problem is what is chewing up the belt.

So, my question is, in that mechanic's poking around, could he have crossed some wires or done something that causes the rear blower motor to stay on?