[TwigMonster]

This morning was brutally cold. below zero wind chill. After briefly warming up my car, including rear window defrost, I heard a "pop" at the rear window as I pulled out of my driveway. At first I thought the window had cracked. it would rattle, creek when I hit bumps. After making it to work, I inspected and didn't see any cracks. This afternoon it warmed into the 20's. Heading home from work... nothing, perfectly normal.

Anyone have a similar issue? I'm gonna get it checked if it happens again. But I'm wondering if others have had a similar issue.

2017 Ruby Red GT premium, 6sp. manual.

 

[Travis98146]

To my knowledge, windshields and rear windows shouldn't make any kind of noise (unless it's on a convertible top). If you're getting a rattle/creak/pop, then it's loose in the frame/seal (hopefully, it's still under warranty).

 

[Beechkid]

IMHO, I'm assuming you are using an electric (hot wire/glass integrated) why in the world are you using an electric rear window defroster in freezing conditions...….. I lived in snow country myself and NOBODY does this without expecting expensive damage.....


just not the best decision IMHO.....

 

[JBert]

. . . why in the world are you using an electric rear window defroster in freezing conditions...…..

When else would you use it?

Now that you mention it, hot wires on extremely cold glass could cause some expansion issues, but I've been parking my cars outdoors and using the defroster to melt the ice off for as long as they have been available, and never had a problem.

If I remember correctly, the thermal expansion coefficient of glass is much lower than steel, meaning the window will expand and contract less than the steel body around it. So you probably have some interference issues with a hole that is too small for the window, until it warms up a bit; and the popping noise was something giving somewhere, hopefully it did not do permanent damage.

 

[Beechkid]

When else would you use it?

Now that you mention it, hot wires on extremely cold glass could cause some expansion issues, but I've been parking my cars outdoors and using the defroster to melt the ice off for as long as they have been available, and never had a problem.

If I remember correctly, the thermal expansion coefficient of glass is much lower than steel, meaning the window will expand and contract less than the steel body around it. So you probably have some interference issues with a hole that is too small for the window, until it warms up a bit; and the popping noise was something giving somewhere, hopefully it did not do permanent damage.

Now i'm showing my age a bit here, but I lived in snow country for about 10 years and worked in a (yes) old fashioned gas station at a ski resort area...….. the regional safetylite (spelling) rep use to leave us a case of "safety type brochures' to hand out to the "flatlanders" who would drive up for skiing..... it explained why you should not use an electric rear window defroster when snow or ice (even light surface ice/heavy frost) has formed on the window..... many a shattered back window (even in the gas station on more than one occaison)...the brochure had a toll free number to call for replacement …. and yes, the gas station owner kept a stack of cardboard boxes and duct tape for covering up the broken out window…..and in true resort fashion...… we sold the cardboard and duct tape for the DIY for $2, if we did it...it was $5.


Perhaps the modern cars the hot wire heats up slower or at a lower temp or both, but IMHO, seeing so many "shatter" of a 10 year period (in the late 70's through early 80's), IMHO, I would just use the old hand removal method to initially clear things up.

 

[Dana W]

At the rate my wire defogs my rear window, the car heater beats it to the draw every time.

When I used to live up north I melted tons of ice off my rear window with the wire and never had a problem in all kinds of cars. In fact i've never experienced a broken or cracked rear window.

Now, I did have a neighbor who poured a teapot full of hot water over his windows. Nothing broke until he hit the second window then the windshield and drivers window pebbled all up nearly simultaneously.

 

[Dana W]

The popping noise was probably the hard frozen black glass adhesive RIPPING some paint off the inside of the window recess.

 

[TwigMonster]

IMHO, I'm assuming you are using an electric (hot wire/glass integrated) why in the world are you using an electric rear window defroster in freezing conditions...….. I lived in snow country myself and NOBODY does this without expecting expensive damage.....


just not the best decision IMHO.....

i understand the point you are making and it makes sense. but like others, i’ve never had any problems with any other cars i’ve had. including a 2006 mustang gt. i actually considered not turning the back defrost on, but if you switch on high defrost it automatically switches the rear defrost (wires) on. that’s what happened.

thanks everyone for your replies.

its under warranty. i will schedule visit to the dealer soon.

 

[Cobra2572]

Just as a point of clarification the heated grid is silver based ceramic paint that is silk screened on the glass and then “baked”into the glass during the tempering process. The screening process takes place in a climate controlled room. The silver paste is mixed with oil to a measured viscosity then some test lites are sent through the furnace and measured for a specified ohm reading to ensure the proper mixture has been achieved before starting production. The heated backlight should not carry enough amperage to shatter the glass. I’m not trying to be a know it all here but I spent half my life in a tempered glass facility in north central Ohio and never heard of this being a problem. Now you know everything that I know. Windshields are not tempered for obvious reasons and are much more fragile, as I’m sure we all know. Thanks for tolerating what is meant to be a helpful comment.

 

[07redstang]

The only time I've ever seen a rear window break due to the defroster is when the timer didn't turn it off. In normal operation it should not happen.

 

[JBert]

Now i'm showing my age a bit here, but . . . .

LOL, I can more-or-less remember those days too . . . I guess we could file this under "back in the day stories"

"back in the day sonny, before we had safety glass . . . "

. . . . I lived in snow country for about 10 years . . . I walked 2 miles to and from work, uphill both ways . . . rep use to leave us a case of "safety type brochures' to hand out to the "flatlanders" who (had) ..... many a shattered back window …. and yes, the gas station owner kept a stack of cardboard boxes and duct tape for covering up the broken out window…..we sold the cardboard and duct tape for the DIY for $2, if we did it...it was $5..

:grin: > :surprise: :heha:

 

[ONEZ ST]

Never had glass break for crack using a rear defroster but I have heard many pops in freezing weather when moisture froze the parking break pad to the rotor and it it broke free when the car moved.

Is it possibl the ubercoId rear shock/strut is making the noise which is transmitted near the rear window area?

 

[Dana W]

I don't have anything important to contribute, so I'll do it anyway. snowman.giffreeze2.gifsnowman.gif

Our Subaru Outback (The unofficial skiers' car) has defrosters in the front windshield with really wide heat grid stripes, made to break the wipers loose from ice, and the rear defroster also has a radio antenna in it, and they share a common ground, which is not uncommon.

It's not how hot you heat glass, it's how fast you create a temperature difference in the glass.

By the way, Pyrex measuring cups and gas fireplace screens are not glass, they are ceramic.

Did you know that some people say that glass is actually a fluid, but it isn't. it's an amorphous solid with some properties of a fluid, and some of a solid.

Originally posted by beechkid (I think),

". . . I walked 2 miles to and from work, uphill both ways . . ."

Yeah but, I hadda do it ...barefoot, in the snow, after kindergarten class, uphill both ways...:grin:

I only care about this stuff a total of about 3 mornings a year since I live in Florida, :surprise:and this coming morning is going to be one of the three.:surprise:

 

[JBert]

Originally posted by beechkid (I think), . . .

ha, no I have to confess that was me taking liberties with my quote of his post, but it still makes a funny story

 

[Howelldaddy]

When I lived up north, I always used my rear defroster with never any problems. I did this for 50 years.