rear window defroster gets it’s operational juice via wires that are connected to tabs at both sides of the window heating element. On our project car, a C5 convertible, the passenger-side tab broke off, thus rendering the rear window defroster non-functional. If you have the tab that came off, replacing the tab isn’t hard, but there are some precautions that have to be considered – mainly, not using too much heat when re-attaching the tab or attaching a newly-fabricated one, as we did here.