FMB, in my 8-year-old (Whirlpool-made) KitchenAid, I found the wiring diagram, along with some diagnostic info, folded up and wedged in a slot on the back of the kick-plate that's below the door(s).

You'll want to remove that anyway to clean the condenser (if your coils, like mine, are under the unit). That was a major part of my own problem.

For other makes/models the diagrams are on the back panel, or under the unit. And there's also the $15-or-so Whirlpool-published do-it-yourself fridge repair manual, which I just purchased from this site. (It arrives next week.)

G'luck!