If it has replace it and test the heater again.
Car back window heater not working.
There is a chance that you are missing terminal edges on your window heat grid.
Examine the fuse to see if it has blown.
Jumping the car or replacing the battery can solve this problem.
The heating and defrosting system rely on an electric blower motor to move the hot air into the cabin of the car and through the defroster vents.
If the new fuse.
Issues can range from a blown fuse to a bad blower speed controller.
Trace the current path from the fuse to the switch to the timer and on back to the window.
One possible cause for the heater not to work is a break in an element.
Wipe up interior moisture and water droplets with.
Make sure the rear defroster switch and the ignition key are turned on.
As it goes back and forth across the window everything comes on and shuts off.
But the defroster became standard issue for rear windows and the world was a better place.
Heater windows radio wipers all work in the acc key position.
It was widely accepted in the car business that a car more than 5 years old would likely have an inoperative rear.
The battery could be the problem if you find that other aspects of the car are not working in addition to the defroster.
Start the car and it all shuts off.
Turn your windshield wipers on when you get in the car.
Disconnect both wires from either side of the defroster grid and touch one end of your tester to each wire.
However turn on the rear wiper and everything works as long as the wiper is not in the home position.
Then the system stopped working.
If this happens to be the case you can use a soldering gun to reattach them.
How to defrost a car window without a heater step 1.
Use an ice scraper to scrape the windows both inside and out.
Repairing heater element with conductive paint.
If the light comes on you have power.
If the blower motor is malfunctioning the defroster will not work.
Fixing a heated rear window fuse check.
That is until something put a little nick or scratch in one of those delicate lines across the glass.