My Honda Civic 1997 Hatchback DX/ Rear window defogger isn't working properly only the top half is working and the bottom half isn't working at all any ideas on how to fix with out replacing the whole window?

 

inspect for the grid on the glass, there is probably a broken strip on the grid, it can be refill with low temp solder, put tape to control the flow... a bit tricky...
a bunch of low temp solder

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Identify the Broken Line and Clean It

To identify the broken line, you can watch your defroster in the morning to see which section is failing to properly work or you can check each line with a voltage tester. Once you find the broken defroster line, make sure you turn off your defroster. Turning it off before you begin cleaning and repairing it is important for many safety purposes.

Once have turned off your defroster, you can clean the area around it. Remove debris or dirt and clean the area with the isopropyl alcohol and a soft cloth.

Prepare the Line

With your masking tape, tape the upper and lower ends of your line to keep it straight, hold a broken part together, and protect the glass around the line. You’ll paint over this line, and you don’t want to get any extra conductive paint on the glass that surrounds line.

Apply Conductive Paint

Before applying, thoroughly shake the conductive paint. Using the brush that comes with the paint, apply a thin line across the damaged line. Wait 5 minutes then add a second coat of conductive paint onto the line. Wait another 5 minutes, remove the masking tape, and turn on your defroster to make sure it works.

The conductive paint will rejuvenate a faulty defroster grid line. When your defroster grid line is scratched or damaged, the electrical current is broken, so the conductive paint repairs the overall electrical current. The right type of conductive paint can be found at any automotive repair store.

Or pop mechanics

https://www.popularmechanics.com/car...a2073/4221212/