A rear slider window assembly for a vehicle includes a fixed window panel, a frame portion and a movable window panel that is movable along the frame between a closed position and an opened position relative to an opening of the fixed window panel. A first heater grid is disposed at the first panel portion, a second heater grid is disposed at the second panel portion, and a third heater grid is disposed at the movable window panel. A first busbar is disposed at the fixed window panel and extends at least partially across an upper or lower panel portion of the fixed window panel. The rear slider window assembly includes an electrical connector for electrically conductively connecting the third heater grid to one of (i) the first heater grid, (ii) the second heater grid and (iii) the first busbar.