Its only on the left.  The big rear window has a defroster, it is hooked up with wire lugs (not a plastic connector) on black and yellow wires.   The same wire connectors on blk & yel are hanging out at the ceiling where they would connect to the side windows, but those windows don't have the defrosters.   I wonder if that is not "normal"?   Maybe I can ask my wife to find my DVM and bring the tractor closer to the house and I could see if/when it is energized.  It would be fun just to sit in it.   Brand new (to me) and I can't do anything, so frustrating.