Windshield hazing... but doesn't appear to be from interior outgassing

Factual Questions
1

I bought my Subaru Impreza new in February 2008. For the first 2 months or so I had to constantly clean a haze film off the glass (got so bad I needed to keep a rag with me for occasional cleaning while driving).

I understand that the plastic in modern cars is usually the culprit due to outgassing. But, here’s the weird part.

Warm weather arrived and it seemed to become less frequent, or got to be so intermittent as not noticed between normal cleanings.

Flash forward to this past December when a rock strikes the windshield, necessitating replacement…

New windshield, and again that oh so frequent hazing! And again, it’s winter and cold out.

I thought outgassing was worse in hot weather?

BUT, how can it be outgassing if the problem went away nearly 2 years, only to return thanks to a new windshield?

A few facts: I do not smoke. Ventilation always set to windshield and feet, which I believe automatically activates the a/c for defogging (not the reason I set it that way… cold feet and better ventilation is all).

2

Is the A/C button pushed and the light on?

I have found that even in the winter, with the heat on, if I don’t turn on the A/C button, that the inside windshield will begin to fog up from the occupants breath.

3

I have this problem regardless of weather, though it does seem slightly worse in the summer. Alcohol does better than anything else at clearing it up.

4

If the substance is difficult to clean, mostly smears when you wipe it, it could be a leaking heater core. When small amounts of coolant leak out of the core the antifreeze gets blown onto the windshield.

Your car is too new to where this would be expected, but a manufacturing fault is a possibility.

5

My first guess would be the fresh/recirc button…make sure it is on fresh air.

As a teen we’d ride in a friends car who left the setting on recirculate with the intention being to keep the warmed air inside the car. He’d have to roll down a window after a few minutes to let out the humidity. We discovered that setting it to fresh air would allow that humidity to escape and the windows were again able to be seen through clearly. These days, if any of the windows start to fog over, I’ll open the rear windows a crack to draw out moist air.

I think you can also get anti-fog treatments that are intended for the inside of the windshield. I haven’t had any experience with them though.

6

Throw air at the window when it’s needed. Why run the ventilation setting so that it’s always blowing on the windshield? Even with the blower/fan off, air incoming just from vehicle motion bounces off the windshield. Who knows what sort of pollutants are in your area? Whatever they happen to be, their first chance to deposit themselves once invited into you car is the windshield.

I’d opt for vent settings that blew air everywhere but the windshield, and would direct it towards the windshield when needed. Benefit: your A/C compressor will last longer (they ain’t cheap) and without the a/c compressor running constantly, you will get more power to the wheels and better fuel fuel economy.

7

If it’s on the windshiled/defrost setting, then by default it will be on fresh air. I don’t think I’ve seen a car made in the last 15 years that lets you “override” the system and have the defrost and recirc on at the sametime.

8

Interesting answers, but I was hoping for a reason that centered on the fact that the hazing disappeared for nearly 2 years, only to return when I had the new windshield installed.

So, happened when car was new = new windshield, but also winter.

Returned with newly replaced windshield, also in winter.

Maybe I need to apply something to the glass?

Whatever it is, it’s driving me crazy.

9

You first need to find out if it is just water condensation or something else. If it’s water, most likely the new windshield has not been properly installed and moist air is getting in around the edge somewhere. If it’s not water, then zwede’s post above is the likely answer.

10

Just a week or two ago, I was on a road trip and had this same problem. I was running the heat, having it blow at the feet and dashboard (because I don’t like it blowing in my face), and the windows were getting so fogged that I had to turn on the AC just to dry the air out a bit and keep the windows from fogging.

Finally I figured out that, as cantara guessed, I had it on recirc; once I switched it to fresh air, I turned off the AC and blew hot air straight onto the windshield, with no fogging.

My car is a 2008 Mini Cooper, and it let me do exactly that.