Is using hi setting for defrost in snow and ice really bad? (Buffalo: live)

[sabre364]

Alright, this is my first post here but figured I'd get some answers.

Now I happened to be looking around in the Wyoming forum on here (dont ask) and I was reading a thread about automobiles and dealing with cleaning them in the snow.

These were the tips in order of importance
1. dont pour hot water on the windshield - it will crack
2. dont turn your defrost on high, too much heat - it will crack
3. something about a windshield blanket or some such mess
4. bad conditions you gotta use deicer stuff that costs a lot or make your own sort vinegar/water, etc

Now 1 and 4 makes sense to me. Though we don't experience those kinds of wind they do out west, nor do we get -20 deg temps regularly. We do get a lot more snow, but there it is all drifts and VERY windy. THe only time I've used hot water is one or two times when its been solid ice at ~32F and used lukewarm water on the wiper blades very carefully.

3 i have no idea what the hell they are talking about, I guess it makes sense if its that remote or something and cold

My question is about 2. Both my dad and I have always turned on the car, cranked the defrost to hi, heat to hi, and started cleaning. My dad had remote start back when we didnt have a garage and would turn on the defrost before he turned it off for the night so when you remote started it turned on immediately. I got remote start for the first time for this upcoming winter. Would this ever actually crack the windshield? We've always done this and had no problems. I guess theoretically it could but...



I am still trying to puzzle out some of the WY folks suggestions though. They all recommend snow chains and generally a 4x4 if you are doing long journeys out in the middle of nowhere WY in the winter. Massive drifts all over seem to be common, the oldtimers all talk about getting stuck. Cities don't get as much snow + plowing so they figure reg cars should be fine there. But none of them recommend snow tires, good all seasons is fine by them. They also all hate studs, etc.

[CAugust]

i turn mine on high and never had it crack - they must have some hot heaters out there in their cars lol........

[BuffaloTransplant]

The heat may be from people who have special engine block heaters. My cousin lives in rural MN and he has one in his car. It gets quite toasty.(I have no idea how the thing actually works) I would assume if it heats up the engine ( and snow or ice off it??) that that heat would go to the windshield, just like the defroster gets heat in our cars from the engine itself?

If something heats the air hotter on a much colder day, I guess cracking is possible.

[sabre364]

Originally Posted by BuffaloTransplant

The heat may be from people who have special engine block heaters. My cousin lives in rural MN and he has one in his car. It gets quite toasty.(I have no idea how the thing actually works) I would assume if it heats up the engine ( and snow or ice off it??) that that heat would go to the windshield, just like the defroster gets heat in our cars from the engine itself?

If something heats the air hotter on a much colder day, I guess cracking is possible.

maybe this does have something to do with it...they plug in the heaters when its real cold (almost a neccessity for most diesel trucks - newer german diesels found in mercs and the grand cherokee have fancy glow plugs, they fire up just fine even at 10 below) to the wall outlet. It keeps the engine block warm, so it simply turns over more easily. Now that wouldn't affect the heater core too much, but I guess maybe since the engine is up and running quickly, it could be pumping out hot air that much faster. :dunno:

[UpstaterInBklyn]

Seems like an urban legend to me.

I'm no physicist, but I don't see how even a fully warmed up car defroster could change the temperature of the glass rapidly enough to cause thermal shock (cracking).