Where are most car thermometers located? Rear bumper?
Are they accurate?
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In the door mirrors on my last car.
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My Corsas was in the front bumper but well away from the radiator. Not sure where the Fiestas is and my Panda dosn't have one as it is poverty spec.
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Anyone know where they are in an Astra H?
I never knew I needed one until I got this car!
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>> Anyone know where they are in an Astra H?
Vauxhall used to put the sensor on the lower corner of the nearside bumper, by the front wheelarch
but from the Omega and Vectra-B onwards they put them just below and behind the front numberplate in the bumper. That's where yours will be.
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Thanks, VxFan. It seems pretty accurate - or, at least, it always seems to match the thermometer on my back fence!
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My car has two ambient temperature sensors, one for the climate control system and one for the dashboard display. they are both located behind the grille, in front of the radiator and aircon condenser. The dash display matches the thermometer in my garage, so I assume it is accurate.
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My Alfa has its sensor on passenger side wing mirror. Mine seems to be accurate
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I haven't a clue where mine is. It suffers from heat soak when the car is parked but reverts to its true reading quite quickly.
It's 3 degrees outside now and raining a bit. Alhamdulillah!
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3 Degrees you mean +3 OMactualG where ?
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His car is a derived Yank tank, its 3 degrees Fahrenheit.
Or the ones without Diana Ross.
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>> 3 degrees Fahrenheit.
No, it was Celsius. You can get the readout in Fahrenheit if you want.
The thaw is still on now.
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It's warmed up here, only -5C at the moment with freezing fog.
Last edited by: Old Navy on Mon 20 Dec 10 at 21:12
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plus..yes plus....1 degree in the New Forest, still bloomin' slippy out there though; slight sideways moment in SWMBO's Zafira coming back from Morissons..whoops.
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In the Golf IV it's located behind the front bumper on the nearside. I've had various cars which have had their sensors on the door mirror, and these are badly affected by the interior temperature / heater output.
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"I've had various cars which have had their sensors on the door mirror, and these are badly affected by the interior temperature"
Even more badly affected when some dickless adolescent nicks the mirrors.
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>> slight sideways moment in SWMBO's Zafira coming back from Morissons..whoops.
Careful spamcan. Old Navy will think you can't drive if your car wriggles a bit on ice.
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It is around -1 here now, the thaw started to the extent that the snow slid off the FocuST's bonnet though it is now stopped.
The FocuST and 120i seem quite accurate as was the Mondeo, its tenure overlapped with the FocuST and their read-outs were aligned, however the Clio has always read about 1 or 2 deg lower than the other cars and therefore I reckon about 1 or 2 degrees below ambient.
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Had fresh snow tonight, about an inch, the wet stuff. 0.5c outside now
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I've not checked the temperature here but it was -7 deg C at 5pm. Expected to go down to -8 soon and then end up at -8 at 9am too. If the BBC is to be believed. If they are then it might only get as high as -5 deg C here tomorrow.
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>>The FocuST and 120i seem quite accurate as was the Mondeo..>>
My last VW and the current Jetta's temperature readings match those of a friend's fairly new Mondeo; we compare them occasionally out of curiosity, but it's of far more interest at present (-8.5 degrees C around 11am today, Monday).
Last edited by: Stuartli on Tue 21 Dec 10 at 00:00
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We are all very impressed by the accuracy of these thermometers with cars attached.
'Just slip this Lexus under your tongue Mr X. Or if that's uncomfortable, given that you are in a straitjacket which renders your armpits unusable for the purpose, we can... er... Nurse! Turn the patient over and hand me that tub of Vaseline...'
Last edited by: Armel Coussine on Tue 21 Dec 10 at 00:07
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Buy a thermometer and we'll throw in a Perodua Kelisa free....
Buy two thermometers and we'll throw in three Perodua Kelisas free....
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>> Where are most car thermometers located? Rear bumper?
>> Are they accurate?
Does it matter? They're of academic interest only.
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>> Does it matter? They're of academic interest only.
Of course it matters. You wouldn't want the doctor shoving it in the wrong way round.
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>> >> Does it matter? They're of academic interest only.
>>
>> Of course it matters. You wouldn't want the doctor shoving it in the wrong way
>> round.
We have one for the dog, that goes in one end - and one for the humans that goes in the other.
I sincerely hope mix-ups have never happened,
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>> >> Where are most car thermometers located? Rear bumper?
>> >> Are they accurate?
>>
>> Does it matter? They're of academic interest only.
>>
You've just answered your own question FT.
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Mrs VW very acurate, the C5 less so. It reads well at low temps, but when it starts to warm up it tends to read a fair bit over. I susspect its mounted somewhere where the colour of the car could influence it such as the wing mirror.
We did have a picasso and you could feel the temp guage sticking out of the bottom of the mirror. On a cold day if you put your finger over the sensor you could watch the numbers tic up on the dash
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>> We did have a picasso and you could feel the temp guage sticking out of
>> the bottom of the mirror. On a cold day if you put your finger over
>> the sensor you could watch the numbers tic up on the dash
>>
my old Laguna had the same set up, did the same thing.
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Nope. I've re-read that, and I'm not getting you. You will have to explain.
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Just realised my obvious mistake....I mean the temp sensor sticks out of the wing mirror
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My 2010 KIA Cerato doesn't have an external temperature display, and it's one feature I miss. Needless to say the 2011 model now has it as standard... Very useful indicator on those damp autumnal nights and early mornings, when you're not sure whether ice might be starting to form on the road.
As an aside, I once saw 54 degrees C posted on the dashboard of my XC90 after I'd parked it for an hour in a dusty car park in the desert outside Dubai... And it was pretty accurate I reckon!
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My mate had just got his brand new Megane back from the dealers as all the dash bulbs had gone, he was giving us a tour round his home town, one darkest december.
I pointed out to him that there is no way, in the middle of december that its 32c outside, "what" came the reply and sure enough when it was actually just above freezing, the car was indicating it was the middle of summer.
"oh no" im going to have to take it back to the dealers again! was the reply.
Last edited by: Redviper on Thu 23 Dec 10 at 09:07
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>>My mate had just got his brand new Megane back from the dealers as all the dash bulbs had gone<<
Why doesn't that surprise me.
:)
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>> Why doesn't that surprise me.
>>
>> :)
>>
too true :-)
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>> I pointed out to him that there is no way, in the middle of december
>> that its 32c outside, >>
The car was probably displaying 32 deg F, i.e. 0 deg C.
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i thought that but it displayed 32c (the symbol for celsius)
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>> external temperature display... Very useful indicator on those damp autumnal
>> nights and early mornings, when you're not sure whether ice might
>> be starting to form on the road.
If you use a thermometer for that, by the time you find out, it'll be too late.
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My friend and I did end up in a ditch (he was driving) in an early Saab 9000. We were sat there congratulating ourselves on being unharmed and wondering how it happened, when just at that moment the external temp thing displayed a warning.
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BMW have a similar sense of humour - once you've dug it out of a foot of snow, cleared a foot of snow from the roof then slid to the frozen door as soon as you press start it helpfully chimes a snow warning.....
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>>My mate had just got his brand new Megane back from the dealers
Just proves you can fool some of the people all of the time...
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Can't tell the temp' yet as I've only just got out of bed!!
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In my car, at 4 °C a light on the fascia comes on and there's an audible warning. There's another audible warning at 0 °C. The light remains on until the temperature exceeds 4 °C.
I've found it very useful during this cold spell. I know that when the light is lit I need to be extra careful and to moderate my speed.
Last edited by: L'escargot on Thu 23 Dec 10 at 11:53
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Depending where exactly the sensor is mounted, I reckon wind-chill must have an effect on the reading as when I drove back along a road which 4 minutes earlier was showing -4°, was now showing -1°
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>>I reckon wind-chill must have an effect on the reading
That's a shame - this thread was doing well in avoiding that particular tedious error until now.
Whatever is happening, it's not "wind chill", it can't be. Much more likely that you were actually driving through an area where the air was actually cooler.
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...this thread was doing well in avoiding that particular tedious error until now...
That reminds me, I must up the anti-freeze concentration in my washer bottle.
The non-existent wind chill caused some very existent ice to form on the windscreen - but only at speed.
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It kinda makes sense to me.
If you were tootling about town, your warm engine would heat up everything else in the engine compartment -- even things out of the way like the water bottle would probably benefit from heating by convection.
Then if you hit the motorway, your warm engine is still warm obviously but there's no way it could heat the air around it -- the air's constantly changing. Also even radiation to the other parts in line of sight wouldn't be as effective, the radiation effect would be fighting the cool air passing through the engine bay cooling it all down again.
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...It kinda makes sense to me...
I agree with all you say, Skoda.
But I reckon the windscreen getting colder at speed - however that happens - plays a part.
If I blow hot air from a hair dryer onto, say, a drinking glass placed on my kitchen bench, the glass gets warmer.
If I glued the glass to the bonnet of the CC3 and set off down the road in this weather, it would get colder.
I'm convinced the glass would get colder faster in moving air. than it would if I just left it outside.
Last edited by: Iffy on Thu 23 Dec 10 at 12:39
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>>But I reckon the windscreen
Firstly, wind chill is the effect as felt by a human, so, using the term for an inanimate object is, from a purely pedantic point of view incorrect.
The point about a windscreen freezing up at speed is that exposure to the wind will cool an object which has been heated down to the ambient temperature more quickly - yes!, this is simply heat transfer via convection, nothing more, nothing less, and definitely not "wind chill"
In the screenwash thread, the only person who clearly understands was RichardW - his post summed up the effects perfectly.
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..yes!, this is simply heat transfer via convection,...
Fair enough.
Because the windscreen washer fluid doesn't freeze on the screen when the car is at a standstill, there is a temptation to think the screen is colder at speed.
Presumably, the washer fluid would freeze on the screen at standstill were there no other factors, such as engine heat, involved.
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>>Because the windscreen washer fluid doesn't freeze on the screen when the car is at a standstill, there is a temptation to think the screen is colder at speed.
It probably is colder at speed, but, the windscreen is being heated by the air coming out of your heater ducts. At standstill, the amount of heat going into the windscreen versus the amount leaving via conduction, convection and radiation means that the windscreen will reach an equilibrium temperature where the screenwash doesn't freeze.
When you get going at speed, the now forced convection from the wind removes heat from the screen more aggressively, bringing the equilibrium temperature of the screen down, particularly those parts of the screen further away from the heater ducts.
As the screen does have a source of heat from the heater which plays a similar role to the blood supply in a human being's flesh and skin, the cooling mechanism described is similar to that by which we feel "wind chill", but, as the screen is inanimate, it's not "wind chill".
In the case of your windscreen, iffy, the mechanism is quite close, and the use of the term "wind chill" for what you describe is almost acceptable, but, for those items which aren't heated, particularly items like temperature sensors, then "wind chill" really is inappropriate, as there is no similar mechanism in play.
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There's more to it than that, since the screen, when "washed", is wet with various stuff.
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...the cooling mechanism described is similar to that by which we feel "wind chill", but, as the screen is inanimate, it's not "wind chill"...
Thanks NC, that makes sense.
I'm not hung-up on using the term 'wind chill' for windscreens and will restrict its use to animate objects in future.
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>> In the screenwash thread, the only person who clearly understands was RichardW - .............
I thought I did pretty well in the Washer Jets Frozen thread.
"Windchill only applies to living things. en.wikipedia.org/wiki/Wind_chill When it's windy the moving air takes heat from your body because the air temperature is lower than your skin temperature. Once their temperature has stabilised, inanimate objects can't be any colder than the surrounding air. Heat transfer only takes place when there is a temperature difference between the object and the air ~ it's a law of physics."
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>>Windchill only applies to living things
Tip top!
Sorry L'es
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>>Whatever is happening, it's not "wind chill", it can't be<<
We'll have to conduct a double blind Scientific test N/C, as I was in the same position on the same road, but going in the opposite direction at the time.
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And ... There's more - I was heading East when the thermo was reading -4°, i.e. into the Easterly wind.
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My temperature sensor is in the airflow behind the grille, road speed has no effect on the displayed temperature. Probably because it is not a warm blooded device. :-)
Last edited by: Old Navy on Thu 23 Dec 10 at 12:56
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>> road speed has no effect
>> on the displayed temperature. Probably because it is not a warm blooded device. :-)
Wind can have an effect on the temperature of a non-living device though, so why couldn't it affect the temperature detected?
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>>Probably because it is not a warm blooded device. :-)<<
Bit like Zero then ;-D
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>> My temperature sensor is in the airflow behind the grille, road speed has no effect
>> on the displayed temperature. Probably because it is not a warm blooded device. :-)
It must be broken then. Because it IS colder around the sensor when your car is moving.
Wind chill. What is it?
It is the effect whereby it can *feel* colder than the immediate ambient temperature.
Note *feel* colder, not actually colder than ambient.
Now when you car is moving various parts of it (washer jets for example) will be cooled to local ambient. If ambient if freezing they will freeze.
If you stop the heat from the engine will radiate and unfreeze them. The washer jets wil be higher than ambient.
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>> It is the effect whereby it can *feel* colder than the immediate ambient temperature.
>> Note *feel* colder, not actually colder than ambient.
>>
Complete and utter cobblers, inanimate objects don't "feel" anything.
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I didnt say it applied to inanimate objects as you say they have no feelings. It was meant to refer to animate objects
I though that would have been pretty clear. Do keep up ON.
Last edited by: Zero on Thu 23 Dec 10 at 13:39
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So how does my temperature sensor "feel", or respond to, airflow?
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It doesent feel
Do I really have to spell this out to you?
Your car engine is HOT. Heat radiates from your car engine outwards towards your temperature sensor. The air around your temperature sensor is HOTTER than the air further away.
With me so far? Good.
Now when you car is going along, COLDER air (ie the air thats not affected by the heat radiating from your engine) is forced round your sensor, if as you say its mounted in your grille.
Therefore your sensor should be reading actual changes in temperature around itself.
Ok?
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Ah, glad you agree with me. So my sensor does not sense speed changes or airflow, only when I am stopped and heat radiates forwards.
Last edited by: Old Navy on Thu 23 Dec 10 at 14:13
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"My temperature sensor is in the airflow behind the grille, road speed has no effect on the displayed temperature"
Age is a dreadful thing.
or the water in Scotland has detrimental effects on the mind.
Last edited by: Zero on Thu 23 Dec 10 at 14:27
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>> Ah, glad you agree with me. So my sensor does not sense speed changes or
>> airflow, only when I am stopped and heat radiates forwards.
I don't know whether I am agreeing with you here or not ON, but the faster airflow will have a cooling effect on the sensor's "probe" which could lead to a lower temperature reading.
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>>but the faster airflow will have a cooling effect on the sensor's "probe" which could lead to a lower temperature reading.
Generally, no, that's not the case.
If the probe is badly sited, and picks up heat soak from the engine when stationary, yes, when that effect is removed by motion, the displayed temperature will drop. The probe has no heat source within it, and will simply tend to record the ambient temperature.
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>> >>but the faster airflow will have a cooling effect on the sensor's "probe" which could
>> lead to a lower temperature reading.
>>
>> Generally, no, that's not the case.
>>
>> If the probe is badly sited, and picks up heat soak from the engine when
>> stationary, yes, when that effect is removed by motion, the displayed temperature will drop. The
>> probe has no heat source within it, and will simply tend to record the ambient
>> temperature.
How come Number Cruncher? Unless the sensor is at absolute zero it has thermal energy, which will be transferred to the air molecules that hit it. More molecules hitting it, more potential transfer of energy, greater cooling.
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>>How come Number Cruncher?
There isn't any source of extra energy in the probe - the probe isn't heated (for such would surely be a mockery of a device aiming to measure temperature!). The probe, therefore, assumes ambient temperature. In this case, the equilibrium temperatre reached by the probe isn't significantly affected by the wind speed.
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>> ........... the
>> faster airflow will have a cooling effect on the sensor's "probe" which could lead to
>> a lower temperature reading.
Heat transfer between inanimate things/objects only takes place when there is a temperature difference between the things. When the temperature of the probe has reached the temperature of the air then no further heat transfer is possible and the reading stabilises, regardless of the air speed.
See en.wikipedia.org/wiki/Heat_transfer
"When an object is at a different temperature from another body or its surroundings, heat flows so that the body and the surroundings reach the same temperature at thermal equilibrium. Such spontaneous heat transfer always occurs from a region of high temperature to another region of lower temperature, as required by the second law of thermodynamics."
en.wikipedia.org/wiki/Second_law_of_thermodynamics
I'm not just giving you my opinion, I'm quoting reliable sources of authoratitive information.
Last edited by: L'escargot on Thu 23 Dec 10 at 15:24
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"I'm not just giving you my opinion, I'm quoting reliable sources of authoratitive information"
I've never thought of Wikipedia as 'reliable' or 'authoratitive'.
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Yeah that makes sense. I've not had a chance to look through the links yet, but I get the general gist of what you are saying, that even if air molecules are hitting the surface faster, they can't cool the object to a lower thermal energy than they have (because if it was cooler there would actually be a net movement of thermal energy from the air to the object).
So they can cool it faster but not to a lower temperature.
So you could, in theory, see the temperature drop due to moving air, but it would actually just be getting down to the ambient temperature faster.
I can also see where NC was coming from now, with regards to a heat source.
Last edited by: SteelSpark on Thu 23 Dec 10 at 21:18
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Would friction have an effect ?
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>> Would friction have an effect ?
>>
Stirrer! :-)
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Not meant to - but the RAF discovered that the external thermometers on their Bomber fleet consistently gave inaccurate readings in very cold air !
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>> Not meant to - but the RAF>>
Typical MOD procurement, the seat back displays in airliners work OK. :-)
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>> This was WW2 !
>>
Now you tell me. :-)
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I remember a passage in Enemy Coast Ahead or Paul Brikhill's Dambusters that covered it.
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I need to tread very carefully here PU - considering the difficulties we've had with "wind chill"
At very high speeds, yes, you can get a heating effect from friction, however, for cars, it's not an issue.
There is also a heating effect obtained by bringing airflow to a halt - the so called stagnation temperature.
Although the wikipedia isn't a trustable source, and I'm loathe to quote it, there's a page here which describes the effect;
en.wikipedia.org/wiki/Stagnation_temperature
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>> So they can cool it faster but not to a lower temperature.
>>
>> So you could, in theory, see the temperature drop due to moving air, but it
>> would actually just be getting down to the ambient temperature faster.
Exactly.
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...Do keep up ON...
Yes, quite right.
What do you think this is?
An informal forum where you can relax and chat to your online buddies?
Well I've got news for you, it's nothing of the sort.
It's war, that's what it is, war.
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>> It's war, that's what it is, war.
>>
>>
Feel free to join in iffy. :-)
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...Feel free to join in iffy. :-)...
I've got a few battle scars already, as you know. :)
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>> An informal forum where you can relax and chat to your online buddies?
You forgot abuse...relax, chat to and abuse your online buddies...
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Can we have have photos of this alleged abuse so we can have a larf?
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In-car thermometers - BiggerBadderDave
