Defroster Repair and Troubleshooting Guide
Frost Fighter kits are
Planned Products LLC
Interactive Repair Tool - Click the damaged part
Click the defroster part for a repair solution - Click the buss bar for tab bonding
Rear window defroster,
defogger or demister not working? Here is how to repair rear defrosters
Rear Window Defrosters
These grids are connected to a high amperage circuit to provide rapid heating. The average defroster grid heats to approximately 85°+ F (29° C) and are very effective in clearing rear windows in difficult winter conditions.
Defrosters are critical to safe winter driving so when damaged it can mean expensive glass replacement but fortunately repairing a defroster is easy and this can mean big savings.
Grid Lines or Elements
Why Defrosters Fail
In this case check the power tabs on the side of the defroster. Use the 2000 Frost Fighter Tab Kit to conductively re-bond the power tab.
Over the years with sun, cleaning or scratching some of these conductive silver particles can come off the glass creating more and more electrical resistance until the defroster stops working all together. If the grid is scratched you can use the Defroster Repair Grid Kit to fix the areas that have the small breaks.
If the grid is generally shot then you might think about a Clear View defroster replacement kit that can replace the entire grid. See the Clear View Defroster Guide.
Defrosters and WINDOW TINT
If the break is not obvious after close visual inspection, use a volt meter or 12 volt lamp to help locate the damage. Turn on the defroster and touch one meter lead to each of the wide vertical bars along the sides of the defroster. The reading should be between 12 and 14 volts. If the volt meter shows a negative reading, reverse the leads. A good tip is to use tin foil on the leads to protect the grids from further damage.
Now take readings at various places along the horizontal lines of the grid to isolate the break. When you pass over the break, the reading will change sharply. If you do not have a volt meter you can use the Frost Fighter Test Lamp. A really good way to identify broken or "worn out" lines is to switch on the defroster in cold/damp or humid weather to identify which lines are working and which are broken or damaged.
Once a break or breaks in the defroster grid has been located, it’s time to consider how to repair the problem. The Frost Fighter Grid Repair Kit is designed to repair grid damage.
Use the grid kit to precisely mask off the damaged area of the defroster. There may be more than one break in the grid so locate all the damage before proceeding.
After the damaged areas have been located and masked, apply the repair material using the small cap brush supplied. Frost Fighter grid repair kits use a highly conductive silver polymer repair compound. This polymer bonds aggressively to glass and provides maximum electrical conductivity.
The material dries to the touch in 10 minutes and is usable in thirty minutes. The conductor is color matched to the reddish brown colors used in automotive defrosters for nearly invisible repairs. Repairs of up of 3-5 inches are common with the Frost Fighter kit.
Removing the masking tape before the polymer dries leaves a uniform highly conductive defroster repair. It is important that repairs be done at normal room temperatures (or hotter) and that the conductor be allowed to fully cure before activating the defroster.
Repairs can be completed even more quickly by applying heat to the repair. A lamp or hair dryer can be used to speed curing. Care must be used not to damage the glass or any tinting that may be on the window.
Begin trouble shooting a total grid failure by carefully inspecting the thick vertical side bars of the defroster. A break or scratch in one of these bars could cause the defroster to fail completely.
Use the Frost Fighter Defroster Grid Kit to repair any small breaks or scratches in these critical side bars.
The more likely cause of a total defroster grid failure is a separated main power clip/tab. These critical tabs connect the defroster grid with the vehicle’s high amperage defroster circuit and are located on each of the defroster grid’s vertical side bars. These all important tabs can be knocked off of the defroster causing total defroster failure. Look for dangling wires near the sides of the defroster as a sure indication of this problem.
Reattaching Rear Defroster
To reattach these separated tabs, pull the metal clip out of its connector and use the Frost Fighter Defroster Tab Repair Kit to repair the problem. The kit uses a fast curing, two part conductive silver adhesive to reattach the main power tabs to the vertical defroster bars. Frost Fighter silver adhesive comes in two syringes for precise dispensing and is mixed at a simple 1:1 ratio. It is important to mix the silver adhesive for at least 30 seconds.
After mixing, dip the base of the tab into the adhesive to coat the area to be re-bonded to the defroster. Replace the separated tab over the area were it was originally separated from the defroster and rock gently to seat the tab base. Make sure the sliver adhesive overlaps onto the surface of the defroster to ensure the best electrical connection.
The simple Frost Fighter tab repair system is safe for all defroster tabs and will not cause additional damage to the defroster as soldering or other methods of tab repair can do. Frost Fighter tab bonding adhesive cures quickly and bonds aggressively forming both the electrical and structural connection in one simple operation. Repairs are stable in 10 minutes but need 24 hours at 75° F.
Tab repairs can be made in 30 minutes when heated. Use a hair dryer, heat gun or electric heater, heat lamp or other heat source to keep the bonding area warm during the repair and cure period. Heat to between 100 and 130 F (warm to hand) for at least thirty minutes for the best results.
Tab causes lots of damage
to defroster, missing sections - Easy fix
If the tab is broken and the base is still on the window there are several excellent repair options. See our Technical Bulletin 110 - Removing Defrosters Tabs from Window
Once the tab is off and the bonding site is clean, mask off an area around the damage using masking tape, apply the Frost Fighter tab bonding adhesive to the defroster inside the masked off area.
Squeegee flat the material with a mixing pad and place the new tab back in place on the adhesive pad. Wait five minutes for the bond to start the cure then use the hair dryer, lamp or other means to cure the bonding site (100-120F 30 minutes) and your back on the road.
Tab/Clips and Connectors
Replace lost of damaged defroster
Clear View Defroster Kits
These kits match the look and performance of factory installed defrosters, melting snow, ice and clearing mist in minutes for safe winter driving. Available in hundreds of sizes, each Frost Fighter Clear View kit includes strong self-adhesive heating elements on pre-spaced rolls for easy and accurate installation. These grid lines bond directly to the rear window and are color matched for that factory look with an unobstructed view.
Controls and Timing Relays
Clear View kits include the little extras like an automatic timing switch which turns the defroster off after 10 minutes of operation for factory performance and appearance. Clear View kits are the ultimate in after market defroster performance and durability but do require some understanding of 12 volt systems to install.
Other Defroster Problems
If you hear the system’s relay click and the monitoring lamp is on, you know you have current at least to the switch. Now test the voltage at the defroster power clips/tabs (on the defroster) using a volt meter or test lamp with one lead to each of the tabs. If you see 12-14 volts or the test light is on then you have a good circuit and the problem is likely with the grid itself. Think separated tabs, scratches or old age.
Defroster Switch or Fuse?
Warning: NEVER BYPASS THE TIMER OR RELAY PERMANENTLY AS YOU CAN OVER HEAT THE CIRCUIT AND POSSIBLY DESTROY YOUR GRID OR EVEN VEHICLE!
By using these tips and through careful troubleshooting, damaged rear window defrosters can be easily and economically repaired, saving hundreds of dollars in the process.
Our customer service staff tacks the most commonly asked customer questions and posts the answers in our FAQ (Frequently Asked Questions) department. Go to Frequently Asked Questions...
Of course our very own Dr. Defroster is standing (ok, more likely sleeping on the couch in the garage or looking for a second cup of coffee) by to help.
Email your defroster questions to the Doc and he will
be back to you with answers.