We are having the same problem. We have a 2016 Chevrolet Suburban LTZ. We've had two Diagnostics on the heated seats at two separate dealerships. Both have said that the heated seats are operating. But nothing happens when you turn them on. It takes maybe 20 to 30 minutes to get somewhere near lukewarm. Completely unacceptable. Could I get some help from GM customer care? Is there a solution for this?