The rear window defogger lets you see out through the rear view mirror in cold weather. It also melts snow and ice from the rear window. In the Sentra, the defogger breaks down in a limited number of ways, easily fixable in 30 minutes or less.
Locate the fuse box to the left of the steering column. On models after 1999, the fuse box is behind the coin box (2000-2006) or the sunglasses holder (after 2006), but still in the same spot, low to the left of the steering column. Remove the defogger fuse from the fuse box with the tool provided. Hold the fuse up to the light to check if it is broken and if so, replace.
Use an ohmmeter to make sure current reaches the back window. If the ohmmeter registers current on one side of the defroster tab on the rear window and not the other, the tab may be broken. Tabs are easily knocked off and need to be reattached with an adhesive that conducts electricity. Repair kits are readily available in any car supply store.
Test the window side of the defroster tab with the ohmmeter to make sure current is conveyed to the grid filament area. If current reaches the window but the system will not work, the window filament has a break in it somewhere.
Examine the grid filament on the back window because any breaks cause the entire system to fail. From the inside of the car, start from the defroster tab and visually examine the filament for breaks. Some people like to follow the line with their finger, much like finding your way through a maze.
Mask the broken section with masking tape. Paint with silver conductive paint to repair.
Check for a current on either side of the repair after waiting 10 minutes. Cure with a heat gun for 20 minutes.
