I posted a thread about my windshield developing a crack. I did some research and discovered MANY PEOPLE have had this happen. Get in Jeep, turn on defroster, watch crack appear. Not even at freezing temps. Anyone else seen this happen? It happened to me this morning.
This may need posting to stock forum, sorry if thsts so.

 

Mine did it- but after a rock hit it at the very top - it made a pit but didn't crack until I went up to the mountains and came back down.
Now I have a perfect crack straight down the middle.
...Sh*t happens.

If your crack is not because of a rock- My advise is that you take it to the dealer and see what they say.
I would think they would replace it.

 

im not sold on the defroster causes it. it takes A LOT of heat to cause glass to crack, esp at the thickness of a windshield. There has to be a weak point, either a glass defect or chip for it to start

 

Yeah, the defrost is not the cause. it just may have had an effect on the weak point. I looked real close, and if it was road debri, there should have been a mark of SOME type on the paint. It is right on the edge of the windshield.

 

there is a TSB for this I think..

It instructs the tech's to run a ballpoint pen along the crack to see if there is a chip in the glass caused by impact.

I suppose that means that if there is not, then it is warranty.

 

There is a TSB on this. I have not taken my Jk in to have it looked at yet, but am trying to get it in there. My windsheild crack started from the bottom and furthered the damage as I used the defroster. Im not saying the defroster is the culprit, simply stating the glass had damage before. Im positive no rock impacts and have done the pen test. Hopefully I get it replaced under warranty. Keep you posted!!

 

Could this be the reason why when you set your heater to just use inside air, you cannot blow hot air on your windshield? Makes sense now.

 

You use the recirculate for heat? Don't your windows get foggy inside?

Thought that was only beneficial to air conditioning...

 

I have a defect in my windsheild I'm waiting to get fixed I'm getting some stuff from the dealer on January 21, 2008.
It's a black spot "inside" the glass itself, I've not seen this before.
I picked my JK up on December 31, 2007, I didn't notice it at first.

Check your warranty on the glass I think it's 30 days.

If this is the mold they use to form the glass before grinding and polishing, it would cause a defect in every windsheild made with that mold. If it's the glass itself it would be the compounds used to make the glass.

I'll post what I find out.

This happened to my Dad in a 1969 Pontiac Grand Prix back in 1971, it
was subzero, he had warmed the car up for about 20mn with the heat off.
He turned the defrost on full blast and the windsheild cracked.
In Minnesota it gets cold, last February at the Gunflint Lodge on the Gunflint Trail it went to -30F over night, the dog got an extra Milk Bone for going out to do his work ;-) The previous 2 nights it was -20F and -18F. a great romantic weekend.

Because the windsheild is a support to the roof of a "car" insurance covers it.
I don't know about a JK because of the roll cage and you can lower the windshield.

I didn't call a JK a ... I was refering to a car ;-)

 

Two winters here, my heat is almost always on floor/defrost. Temperature ranges from nearly 100 in the summer to well below zero (ambient) last winter (less than that by far wind chill) up along the Saint Lawrence. No issues, no cracks.

Yet.