I believe that it is listed in the manual as a rear window defogger, and it really only melts moderate ice in weather like this.

If the relay is working, it's working. How is the car's voltage? The voltage is notoriously low on these cars when idling with accessories on, which at this temp usually includes the rear-defog, mirror de-ice, washer nozzle heat, heater blower, lights, radio, ... will de-ice better when running at high enough RPM to develop the proper system voltage.

The relay IIRC is in the large "cube" in the middle of the relay array aft of the fusebox, called the convenience-control I believe.

__________________

Gone to the dark side

- Jeff