We just received our first real day of winter here in southern Alberta, Canada, and I used the windshield defroster button for the first time yesterday. A short while into the trip I heard a "pop" type sound, but didn't think too much of it (no other vehicles in front or beside me at the time). Soon after, I noticed a line across the bottom of the windshield directly above the defroster vents. This line turned out to be a crack and it begins and ends at the edges of these vents.

I have read that heating a window too rapidly can cause it to crack. Could this be the cause? I'm not sure how to even cotnrol the intensity of the defrost setting as it seems to take over at a preset fan speed, etc. whenever the button is pressed. I have checked the crack thoroughly, and have not been able to find any evidence of a pit where the crack could have started. If the defroster did indeed cause this crack, would it be covered under warranty? Any thoughts or comments from similar experiences are appreciated. Thanks.

 

My guess is that there was either a previous hit there that weakened the glass or the glass had a defect in it. Tough to prove, but I would make an attempt to take it to Acura first and explain.

I've had this happen to my rear windshield on an 89 BMW 325i, but that was a floating piece of glass and was known to bind and brake with extreme cold. Our front windshield is adhered, so I'm certain the simple fact of heating it was not the cause.

 

You can control the intensity of the temp and fan by turning the temp and fan speed down. Never heard of this happending but I guess it could. I think it would be covered under the warranty.

 

I had this happen before but it was because a rock had hit the windshield. As soon as that first cold day came and I put the defroster on it, I got to watch the crack form on my drive in to work that morning.

 

I never defrost my windshied unless it's necessary. Just imagine what happen next:

1. 30C temperature difference between two layers of windshield (-20C ambient temp and 10C window interior temp)
2. 80km/h wind resistance on windshield (Let's assume no wind and you drive 80km/h)
3. A rock hit the windshield.

My 04 TSX is non-navi, when I turn on the heat it always show "Auto" and the system always blow the air to the windshield. I don't think this setup is suitable for a cold climate location. What I do now is turn it as "Auto" first when I first start up the car in the morning, the wind will not be blown instantly since it's smart enough to wait the temperature rise before blowing. When you hear the sound of blowing, turn it to "Face/Below" setting. If the windshield need to defrost, defrost it and turn it off immediately if it's not required. I did that for last two winters and I don't have any crack on my windshield. Touchwood....