Why at 39 degree?

MonsterTDI09

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Why does the temperature warning ding at 39 degree?
 

dzcad90

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You'll also note the snowflake icon pop up on the cluster.

This is an indicator that the conditions are right for there to be icy roads.
 

All of Us

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Because that's the temperature that VW programmed it to ding at. I'm sure they had 3 research studies that showed that was the optimum temp to use, as well as statements from the VW legal department indicating that that temp represented a reasonable risk for liability exposure from that particular indicator. I'm sure if they left it solely up to the lawyers it would probably go off at around 80° F.;)

Dan
 

#2isgreen

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my heart usually jumps just a little bit when i hear it come on after an hr of driving as i go into a valley near a big river. always worried i"ll look down and see something bad flashing at me.
 

tdiatlast

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Because that's the temperature that VW programmed it to ding at. I'm sure they had 3 research studies that showed that was the optimum temp to use, as well as statements from the VW legal department indicating that that temp represented a reasonable risk for liability exposure from that particular indicator. I'm sure if they left it solely up to the lawyers it would probably go off at around 80° F.;)

Dan
I don't believe this is some sort of arbitrary choice. I think any time you're below 40f, there is a risk of ice formation on overpasses. Of course, there needs to be sufficient moisture present, but I'll bet it's a bit more complicated to combine a moisture sensor and a temp sensor together.

I'm always very happy to have the warning, and when driving a car in the winter w/o the temp sensor/warning, I find myself a little anxious about the road surface.

Just my 2-cents...
 

smketrny

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I want a "There's a deer in the woods beside the road ahead" light on the dash.
LOL. A friend of mine got 3 deer, 2 with the gun and one with his 2009 Ford F150. Pushed the right front end close to the firewall. Was a 10 pointer he hit, and then someone took the deer after he went back for it.

A safe and Happy Thanksgiving to all.
 

TDIFred

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LOL. A friend of mine got 3 deer, 2 with the gun and one with his 2009 Ford F150. Pushed the right front end close to the firewall. Was a 10 pointer he hit, and then someone took the deer after he went back for it.

A safe and Happy Thanksgiving to all.
that's called 'getting even'.

Happy Thanksgiving to all my fellows TDI drivers (we had our turkey last month!)


and don't forget to go shopping on Friday, either buy something for your car or nothing at all!
 

MonsterTDI09

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A deer waring wood be cool.The ding drives my wife nuts I guess there is no way to turn off.
 

tdiatlast

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Did someone say dear? My 87-year-old dad and very recently deceased uncle were reminiscing recently. They confessed to an incident in their early years (both were avid hunters, west of Denver).
Early one hunting morning, they encountered a dear standing in the middle of the road they were traveling. They looked at each other, shrugged, and gunned the engine, taking out the dear (and a headlight and fender). As they got out to snag it, a second vehicle came up behind them, spooking one of them into the bushes, the other driving on with the car.
Well, the second vehicle stopped, 2 hunters got out to check out the freshly killed dear, threw it into the back of their truck, and took off!

Happy Thanksgiving everybody!
 

TDIFred

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salt water below that, and the German engineers use the metric system to confuse things further...
 

TDIFred

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and furthermore, instead of a BING, it would be a little old lady's voice (Betty White's maybe!) saying "Oh dear, it's a deer"!
 

All of Us

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Volks:

I was reading through the OBD scanner forums and found this discussion

http://forums.tdiclub.com/showthread.php?t=300644

On about the 10th post Frugality says that he was able to use VCDS to disable, among other things, the ding that sounds when the snowflake pops up at 39° fahrenheit. Just wanted to throw this in here in case anyone wants to follow up. The 11th post states that he tried and his seatbelt warning is gone but the 39° ding still sounds

Dan
 
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El Dobro

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I thought the ding was just to keep you in practice of listening for warnings about something else breaking on the car.
 
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MostroDiesel

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Just a reminder, at 39 degrees, if you include wind chill into the equation, it's possible for ice to form, especially on exposed surfaces like bridges and overpasses.

I can see that without the ding, a happy, toasty driver might never notice the temperature warning, even if it's a bright yellow flashing light. Personally I like it because on those drives from CT to ME, the temperature and conditions can change and it's nice to be alerted.
 

All of Us

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Personally, I don't mind the ding. That it reminds me that the weather is getting colder and Winter approaching I don't particularly care for, but the reminder about possible road icing is a good thing. Some people were expressing their interest in killing the ding though. Certain times of the year I am looking for that warning, however, the first time the windshield washer fluid warning ever went off, I could feel my heart rate jump.

Dan
 

ZiggyTheHamster

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FWIW, I can never hear any ding due to my music being turned up above "whisper" :)

Seriously though.. the dings really could be louder on this thing.
 

tdiatlast

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FWIW, I can never hear any ding due to my music being turned up above "whisper" :)

Seriously though.. the dings really could be louder on this thing.
yeah...especially the turn signals. I don't mind being reminded when I take a gentle off-ramp sweeper that doesn't engage the automatic turn-signal deactivater, or whatever it's called...
 

steelmb

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Just a reminder, at 39 degrees, if you include wind chill into the equation, it's possible for ice to form, especially on exposed surfaces like bridges and overpasses.

I can see that without the ding, a happy, toasty driver might never notice the temperature warning, even if it's a bright yellow flashing light. Personally I like it because on those drives from CT to ME, the temperature and conditions can change and it's nice to be alerted.
Wind chill does not affect anything that is already down to ambient temperature. If something is down to 39 degrees there is no way to make it colder with wind. If there is moisture present and evaporation is taking place, the wind may accelerate the evaporation and its cooling effect but that is not wind chill that is evaporation. Besides that wind chill temps are only reported below 32 degrees. Reporting wind chill as a temperature is totally bogus and that is why they do not report it above 32 degrees. The effect is still there above freezing but since once you are down close to freezing you can't actually make something freeze with wind chill, reporting a temperature below freezing would be lame and confusing so they don't report it. Wind chill should be reported as watts/square meter or whatever the imperial equivalent is. It is mainly the function of the temperature difference between 2 objects and wind speed. No wind equals no wind chill. No temperature difference also equals no wind chill. To a small degree humidity and other properties of the air may also have a slight effect.
 

MostroDiesel

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Wind chill does not affect anything that is already down to ambient temperature. If something is down to 39 degrees there is no way to make it colder with wind.
I stand corrected. Wind chill is actually only applied to the effect of wind on the temperature detected by the human skin.

Perhaps, then, it's the evaporative factor that makes 39 degrees the dingable figure? Growing up in New Hampshire, I do know that we were always cautioned that ice can form on bridges, etc., above 32 degrees, so SOMETHING must be influencing the ice formation.
 

steelmb

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I think that 39 degrees is probably getting to the range where there could be localized freezing in dips and valleys or whatnot. My friend lives in a valley and their garden always freezes before ours in the fall. Even here our sensor for the outside temp here is about 8 ft off the ground and it can show a few degrees above freeing when there is frost on the ground. You need to have the ding early enough so as that you have a fair warning. There is no use in having it ding when you enter the skid. :D
 

TDIFTW

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fort worth
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IIRC..... going back to my chemstry notes.....

water will freeze at a higher temp because of altitude, so some where in the mountains with a 5000+ foot elevation will cause the water to freeze at a higher temp and boil at a lower temp. i believe that it has something to do with barometric pressure, the lower the pressure the higher the freezing point and the lower the boiling point.

found this on the interwebz:

Freezing Point Depression


A solution will solidfy (freeze) at a lower temperature than the pure solvent. This is the colligative property called freezing point depression.
The more solute dissolved, the greater the effect. An equation has been developed for this behavior. It is:
ΔT = i Kf m
The temperature change from the pure to the solution is equal to two constants times the molality of the solution. The constant Kf is actually derived from several other constants and its derivation is covered in textbooks of introductory thermodynamics. Its technical name is the cryoscopic constant. The Greek prefix cryo- means "cold" or "freezing." In a more generic way, it is called the "molal freezing point depression constant."
These are some sample cryoscopic constants:
Substance Kf benzene 5.12 camphor 40. carbon tetrachloride 30. ethyl ether 1.79 water 1.86​
The units discussion pertaining to Kb applies to Kf also.
 
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