I have a 2008 MKZ. The seat heater/cooler failed late last winter and I finally got around to looking at it. Both driver and passenger seat heat/cool were non-functional. Pressing the heat or cool buttons on the dash did nothing. Looking at the control connector under the passenger seat, one of the wires was burnt. Other solutions found online called for replacing the control module and the wire harness to the control module which will cost a few hundred. On inspecting the control module, I could not see any issues. Usually there is a burn mark on the board or a popped capacitor, but this board looked clean. I drilled the burnt connector out of the wire harness and replaced that wire end with a copper connector. All the connectors on the harness and control board appear to be aluminium which may have oxidised contributing to the burnt connector, hence using a copper connector as a replacement. This solved my issue. Been working OK for the past 2 months.