subject: Fixing Your Car's Window Defroster [print this page] Replacing your defroster grid entirely can be an expensive repair. For smaller cars it can be several hundred dollars, while bigger sports utility vehicles can cost upwards of one thousand dollars.
To prevent having to replace the grid entirely, be careful. The grid is only painted on, so it can very easily be chipped or scratched off.
Make sure you do not put anything in your car that will rub up against the inside of your rear window and potentially damage your defroster grid. Also let children know that they should not touch the back window.
You might be wondering how the grids even work if they are merely painted onto the glass. The grids create a continuous flow of energy going across the glass.
This energy creates heat, and the heat melts the ice. The heat comes from a fuse that is typically located in a very small box near the back window.
That fuse is connected to the battery of your car, which powers the defroster. If your defroster is not working properly, refer to your owner's manual on how to repair it.
Not every car manufacturer gives the same procedure to fix the defroster. To ensure that you do a job that is correct and specific to your vehicle, follow the directions and guidelines in your manual.
Sometimes if your back window is not melting the ice adequately, it is a problem with the fuse. If a fuse is only drawing a low current, it will not have enough energy to send heat circulating around the back window.
Check the fuse with a test light or voltmeter to see if it is drawing enough of a current. Replacing the fuse can be a very inexpensive and easy do-it-yourself fix.
If the fuse is working properly, check the wiring. Sometimes the terminals, which are located on the left and right sides of the glass, fall off.
If this is the case, you can glue them back onto the glass. Before you try anything with the terminal, however, you should disconnect the wiring from the defroster grid.
Failure to do so could cause irreversible damage to the grid and / or electrocution. Remember that liquid and electricity do not go well together.
Make sure you clean the glass with alcohol before gluing as well. Make sure you glue the terminal to its original location so that flow of the current is smooth.
If the problem is not with the wiring or the fuse, it could be with the rear window defroster switch. To fix this problem, remove the switch from its location.
You then use the wiring diagram found in the owner's manual to determine which wires go to the switch and which ones go to the actual grid. Sometimes there will only be two wires so this will be easy to determine, but other cars have many more that do other things and attach to other outlets.
After finding the correct two wires, jump them and see if the grid starts working. If it does than you have a faulty switch.
If there is simply no power there at the switch, then there may be a break in the wire between the fuse box and the switch. Another problem may be that there is a delay in the timer to the switch.
If this is the case, you change the two relays that are to your rear window. This is one located on both sides of the glass; one is to activate the switch, while the other provides the electrical connection to the defroster.
You can buy new ones at your local auto shop for a fairly inexpensive price. Messing with wires can be very tricky though.
Make sure you know what you are doing and are taking safety precautions like shutting of the power keeping open fuses away from liquids. If you are not sure what you are doing, take your vehicle to an auto repair shop and have it done by a professional.
