How to protect your windshield ?
It is a risk factor that too few motorists take sufficiently into account: the weather and climatic conditions in general, in their most extreme variations, from freezing temperatures in winter to extreme heat waves in summer, potentially affect the condition of the windshield. The problem is not so much the level of external temperatures, but the thermal shock caused by the sudden and artificial heating or cooling of the ambient air inside the vehicle by the radiator or air conditioning.
How to protect your windshield from the sun ?
At the height of summer, when the sun's rays are at their peak, the heat absorbed by the windshield remains trapped and accumulates inside the passenger compartment, to the point of raising the temperature to almost unbearable levels.
This effect is particularly noticeable when the vehicle is immobilised for a long time, and without protection, in the face of the ultra-violet and infra-red light emitted by the sun in a straight line. The temperature felt on the dashboard climbs very quickly and can reach 38°C in just ten minutes (compared with 26°C outside), then 44°C in twenty minutes (according to data provided by LaChaineMétéo). The first reflex of motorists to combat this heat is to turn on the air conditioning, without knowing that sudden cooling subjects the glass surfaces to significant internal pressures.
Glass exposed to very high temperatures tends to expand beforehand. A thermal shock that is too violent can therefore encourage the appearance of cracks and even cause breakage in the long term.
What precautions should be taken to avoid this risk ?
It is advisable to park in the shade, to start up the ventilation very gradually before getting back on the road and, if possible, to ventilate the interior of a vehicle that has been parked for a long time in the sun (by leaving a window ajar). In order to limit the infiltration of radiation, some motorists install solar films or sunshades on their windshields (specialists offer accordion-shaped models, roller blinds or integral curtains). It should be remembered that there are athermal windscreens with reflective properties that can reduce the heatting effect.
How to protect your windshield from the cold ?
Same causes, same effects in winter. When the weather is icy and the temperature in the vehicle drops, it is tempting to turn on the heater in the early hours of the morning to get it running at maximum. This should not be done: the cold weather causes the glass surfaces to shrink and they are particularly susceptible to the consequences of thermal shock created by a sudden rise in the temperature in the passenger compartment.
To reduce the risk of cracks caused by these strong temperature variations, it is advisable to protect the windshield from frost with a tarp or pieces of cardboard, which can be placed firmly against the glass by wedging them under the wiper blades.
Among the things you should not do: Use boiling water to thaw the window quickly, use the heating system without moderation and set to its full power. It is better to start the car gently, if possible by idling the engine until the temperature rises a little. Of course, the snow brush, the scraper or the anti-freeze spray remain indispensable tools for a windshield offering the best guarantees of visibility.