If, after turning on the electric heating, the glass surface remains uncleaned, check with a test lamp or voltmeter whether there is supply voltage at the terminals of the glass heating element. To do this, a test lamp (or voltmeter) connect to output «+» electric heater and «mass» body. If there is no supply voltage, check the wiring of the cell power circuit and repair the problem.
If the power circuit of the heating element is OK, check the serviceability of its conductive strips.
The check is carried out with the engine running and the electric heating turned on. Using a voltmeter, measure the voltage on all strips one by one, connecting one lead of the voltmeter to «mass» body, and the other in series to the conductive strips. If the voltage measured by the voltmeter at the beginning and end of the strips is the same and approximately equal to the battery voltage, check the reliability of the contact «mass» heating element wires with car body.
The voltage on the strip should decrease as the voltmeter connection is removed from the positive polarity bus of the element. The voltage must be measured at least in two places at the same distance from the axis of symmetry in order to exclude the possibility of missing a damaged area. If you find a discrepancy in the readings on one of the strips, move the voltmeter wire lead along this strip until the voltage becomes zero. A sharp decrease in voltage indicates a strip break at this point. Mark the rupture on the outer surface of the glass with chalk or a glass grapher for subsequent repair of the damaged area.
To repair the heating element, you can use one of the commercially available special kits. Despite the fact that the kits are made by different manufacturers, their composition is approximately the same and they all come with instructions for use. The following is a typical workflow for these sets.
1. Remove a 6 mm strip from each side of the damaged area.
2. Wipe the damaged area with a clean cloth dampened with alcohol.
3. Stick repair adhesive tape or two pieces of ordinary adhesive tape on the glass at the point of damage to the strip at the top and bottom of the repaired area, and the distance between the pieces of adhesive tape should correspond to the width of the conductive strip on the glass.
4. Thoroughly mix hardener with silver base compound. If the hardener has thickened, place the package with it in hot water and wait until the hardener becomes liquid.
5. Apply the composition to the area to be repaired with a wooden spatula and remove the adhesive tape.
6. Install the heater at a distance of 25 mm from the damaged area and heat the composition for 1-2 minutes. The minimum heating temperature is 149°C.
Note. In some kits, the composition does not need to be heated: it polymerizes at room temperature.
7. If after drying the strip has become discolored, apply a tinting iodine composition on it with a brush - the color of the strip will be restored. After the iodine compound has dried for 30 seconds, wipe off any excess with a clean, lint-free cloth. During the polymerization of the repair composition, which lasts 24 hours, exclude any mechanical impact on the repaired section of the strip.
8. Turn on and check the operation of the rear window heating element.
If the wire has come off the bus, solder it with solder containing 3% silver and rosin paste as a flux in the following order.
1. Clean the solder area on the busbar and the wire strand.
2. With a brush, apply a little rosin paste to the connected places of the wires and tires.
3. Apply a thin layer of solder to the wire strand.
4. Solder the wire to the bus, avoiding overheating of the connected parts.
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