Solution?
I took my TB to a local garage, and the guy replaced the blower motor, which he said didn't fix the issue, and the control module. He said he talked to a GM dealer who told him that when the motor goes, it may short out the module. I'm a little skeptical, but am probably stuck at this point. Also, I realized the tech wasn't aware of the delay that occurs (3-4 minutes on my vehicle - typical?) before the rear a/c kicks on. System is now working properly.