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How Do I Keep My Interior Windshield Glass From Getting Foggy?

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Does it seem like your windshield is always foggy on the inside?  You’re not alone.  Here’s how the pros deal with it.

A reader wrote us this week and asked BestRide why her interior windshield glass is always foggy.  No matter what she does to clean it, it seems like the glass is foggy a day or two later.  We know just what she means.  We auto-reviewers are frequently in new test vehicles and indeed, the windshield, and other glass is always foggy.  Being car nuts, we hate this.  Here is what causes it and how we deal with it.

recirc button

First things first.  If the windows are foggy be sure that your car is not putting on the climate control “Recirculate” button in your car.  New cars do this because it is more efficient to cool the inside air, rather than cool air being pulled into the vehicle.  The universal symbol for the recirculate function is a car with a looped arrow inside.  To turn it back to fresh air either tap it once and watch the light above it go out, or there may be a separate button with an arrow showing fresh air flowing through to tap.  Recirculated air gets moist from your breath and that of your passengers and from water on your shoes and clothes.  The film you see is condensation.

air freshnerFilms like this can also come from contamination you bring into the car.  Those little air fresheners that hang from the mirror or go into the vents are the biggest offenders.  Ditch them.  If your car stinks, you should find out why and deal with that.  Cleaners made to coat vinyl and plastic also off-gas and coat windshields.  Stop using them.  They are not doing what they promise anyway, and the best cleaner for the interior parts of a new car is a damp cloth.  Those plastic “preservatives” that make your dash look shiny just leave a coating behind that ends up on your glass.  However, the recirc button, the air freshener, and the plastics chemicals you add may not be the only problems.

New cars off-gas volatile organic compounds (VOCs).  These compounds are gasses that come from the newer plastics, fabrics and leather of your newer vehicle.  Overnight and whenever the vehicle is not having fresh air brought in, the gasses cool and condense on the glass and leave a film that makes the glass look cloudy.  It is worse in summer when the sun and high temperatures bake out the chemicals.  We car-testers have this problem constantly since we are lucky enough to be in new cars a lot.  After a few years, the heat bakes out all these solvents and other VOCs and the windshield will be easier to keep clean.  You do your part too, breathing them in you big human filter you.  In the meantime, we have some ideas that will help.

armor all glass

To deal with the problem, you need to get the glass clean – really clean – first.  We like non-ammonia cleaners.  One that has worked well for us is Armor All glass cleaner.  Be darn sure you don’t confuse this great stuff with the vinyl and plastic shine-up stuff sold by Armor all (see above).  There are gimmick products on the market that promise to clean your glass, but the best method we know if is to soak the inside of the glass and wipe it down well with clean, dry high-quality paper towels.  They are not all the same.  We like Bounty.  Then do it all over again.  Two times is the trick.

So now your glass is clean, but how do you keep it clean?  Whenever you can, park with a pair of windows down or at least cracked to let the gasses out and fresh air in.  If you park in your garage, put the front windows down.  If you are in a parking lot leave the second-row glass cracked an inch.  Obviously if it is going to rain, you have no choice but windows up.  One pleasant side effect you will notice is that clean glass resists fogging from your breath better than dirty glass.

There are some products on the market as well as some home remedies that claim to keep your interior glass form fogging.  We can’t endorse any, but you can try them.  Our guess is that most of what they do is clean your glass.

Make yourself a window cleaning kit and keep it near the car.  5 minutes a week and good habits will have you looking through clean glass going forward.



John Goreham

John Goreham