Cleaning Windshield


My 2020 Audi S5 has an issue with the interior windshield fogging up. I can use the windshield blower to clear it, but the fog returns pretty quickly. I’ve adjusted interior temp. No real help. I’ve cleaned the windshield interior. Better for a drive or two but the fog/haze/film returns. Is there a product anyone can recommend for cleaning windshield and perhaps deterring the fogging? Thanks!

Do you run the climate control all the time? If not, it might just be that general humidity is fogging the windows. If you do run the climate control frequently, you should take it to a dealer if you haven’t already. I doubt that you exceeded the mileage part of your warranty, and certainly are covered by time.

The best glass cleaner that I have used is Hope’s Perfect Glass, which can be found at Lowe’s, Home Depot, and some supermarkets. If that doesn’t work, then you might try using rubbing alcohol, but you need to be careful that you don’t get any alcohol on the dashboard’s vinyl cover.

If none of that helps, then the only possibility that I can think of is that the heater core might be leaking. On a 1 year old vehicle, that’s not likely, but I suppose that it is possible. Have you checked the coolant level?


IPA won’t damage the dashboard if it’s cleaned off immediately. Still,I’d spray it on the wiper outside the car and then wipe the windows. BTW, IPA doesn’t work well on the window deposits from the dashboard.

I have no ideas about how to clean the windshield but if this been happening since the car was new I would say the fogging is being caused by off gassing from the plastics and other materials the interior is made from.


The fogging you are describing is a combination of humidity and outgassing from interior materials. You can just run your defroster all the time, that will keep the humidity low enough to keep water vapor from condensing on your windshield.

Cleaning the windshield will do the most good, but those deposits from outgassing are very difficult to remove. I don’t know of any product that will remove them without a lot of added elbow grease.

A bucket of hot water with dishwashing detergent will cut through the haze about as well as anything but it can be messy and still needs a lot of scrubbing. If you are sure that there are no plastic films such as a tint film or glare film on the inside of your windshield, the fine steel wool will reduce the workload, don’t apply a lot of pressure to the steel wool though.

Be careful with ammonia based window cleaners because they will remove any applied films. If you are uncomfortable with steel wool, then a blue or white nylon pad will work but it will take more effort. A single edge razor blade will also cut through the film, and anything else applied to the glass. It is about the fastest way to get down to the glass though.

Rinse and dry will good micro-fiber cloths. You will see clearly for awhile. Also rain-x the outside of the windshield for better visibility.

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This work!

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Ammonia based cleaners work well. The spray foam types not so good. White vinegar and isopropel alcohol in distilled water works. Scouring powder…non scratching types… on the tougher films.

Rain X No Fog on the inside helps keep the window from fogging up.

When was window glass invented? 1600’s? You’d think by 2021 the tech wizards would have figured out how to prevent it from fogging up. But apparently not … lol … Good ideas above, esp about using the AC to dry-out the passenger compartment air.

I had one car that would do that, for whatever reason ac blowing through the vents by the windshield would cause fogging. I think changing the airflow to feet solved it, but but not sure, so long ago.

I think this is just Outgassing from dash and other parts. Some vehicles have it more than others and it will stop . It could be weeks or months .

Speaking for my self I am not taking Steel Wool to a new car windsheild not matter how fine it is.

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Agree I woul not do it to an old windshield let alone a new one.

Make a DIY cleaner

  • Mix a bowl of warm water with a teaspoon of dishwashing liquid and add in just a few drops of vinegar (whatever you have in the kitchen should do the trick).
  • Have two microfiber towels ready to go. …
  • Twist the excess water out of the soaked microfiber cloth and wipe the interior of the car windshield.

I add a splash of ammonia instead of vinegrar and alcohol to just to get it to dry faster. .

A vinegar solution such as the above works pretty good on the outside of the window too , especially if the windows have water spots, which applies to my cars b/c I rinse them off with hose water without later wiping the surface dry. For the windows I use about 10% white vinegar (the standard concentration, used for cooking) and 90% water, and nothing else. Works pretty good if used consistently.

I had a couple cans of no name window cleaner from the guys that installed a couple new windshields some years ago. I used them last time I cleaned the cars and wow did it do a good job. Don’t know what it is but labeled “professional window cleaner” or something. Spray it on, scrub a little, and polish with a micro fiber. Never been as clean. When I run out I’m going down to the shop to see if I can buy some more.

Being as I’m an older American we still get a newspaper. A full piece of newspaper or plain white drawing paper that looks and feels like newspaper, crumpled up into a ball, and rubbed dry on the inside of the window works just fine, no soap, no miracle cleanser, no nothing else. If you have access to free weekly tabloids they work too. Try to avoid paper with color photos as it seems to smear more.

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Wonder if rainx would work

7 Best Anti-fog Windshield Treatments & Anti Fog Glasses Cleaner –

If you’re using Armor All or a similar product, stop.

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SAAB at one time came out with a bulletin about out gassing and recommended wiping the dash down with some water diluted with a little vinegar.

In the event this problem is not out gassing I would think that the air compressor in the DEF position should clear it up. The assumption I make is that the A/C is functioning properly.