Buick LeSabre AC blower motor not working - causes and diagnosis

This 2004 Buick Lesabre is in because the customer plans a drive to Louisiana and needs an overall check to ensure it's roadworthy. He also stated the vehicle had been losing oil pretty quickly. Like most older vehicles, I generally expect them to have leaks, as seals don't generally survive the test of time. Once we got it in the air, I discovered that this was the cleanest Buick I'd ever seen, with not a single leak or seep to be found. The customer is serious about his maintenance, and it sho