Dan, the compressor for the lumbar/love handles on BOTH seats is located under the passenger seat. Select a seat, and push an inflate function. Does the compressor vibrate? (you can see it under there).
If it doesn't, disconnect the harness from it and check for 12V when you select an inflate seat function. If you have 12V, replace the compressor. You can read the 8-digit GM part number off it with a flashlight and small mirror. Run the number through www.gmpartsdirect.com
or get it from a wrecker.
If you don't get 12V at the compressor, pull your seat switch panel out, disconnect the 3 wiring harnesses, and carefully remove the screws on the back. Get any dust or crud out of there, and make sure the electrical contacts are clean.
My gut tells me the compressor is bad.