I have always wondered this (I should find my interesting things to think about really)...
How can the external air temperature sensor be accurate?
Surely the heat from the engine and wind chill make it inaccurate. Also where is the sensor typically placed?
It was very cold this morning, but I'm not convinced it was -2c like my car said!
|
Also where is the sensor typically placed?
Underside of a door mirror is one place.
I used to wonder if the thermometer on my Skoda Octavia was fibbing, never seemed to be quite as cold as it suggested.
|
>> Underside of a door mirror is one place.
Never thought it would have been placed there!
|
I had a 206 that fibbed about the temp as well
Its automatic lights sensor was on the wing mirror also (I think) as when the sun shone in a certain direction the lights would come on... in July... midday
My old Octavia seemed quite accurate right down to minus 17 up in the highlands one night
|
|
|
|
Renault and Alfas like to place them under the mirror in a little bulb. No idea how they compensate for wind chill.
Others place them behind the front bumper (vauxhall & ford i think)
My HIre Focus said it was -3 at 07:00 this morning, and given the depth of the frost I have no reason to douts its accuracy.
The Focus ice warning works very well.
A single beep and a solid big yellow warning star when it falls to +4c, a beep and a big red warning star when it falls to 0c
--
RF - currently 1 Renault short of a family
|
The Focus ice warning works very well. A single beep and a solid big yellow warning star when it falls to +4c, a beep and a big red warning star when it falls to 0c
My Mondeo has the same system. I like it.
When it first activated, this season, a couple of days ago it was also a wake up call.....
A/C now auto switched off...Ah! so thats why things are steaming up.
|
|
|
|
Also where is the sensor typically placed? >> Underside of a door mirror is one place.
Front bumper, just below the numberplate on my car.
|
|
|
|
On the Xantia (and Pug 406) it's on the underside of the passenger door mirror so well out of the way of engine heat. In other cars it's on the front air dam to measure the temp near the road surface. Mine tends to rise a degree or so as the car warms; probably stray cabin heat. Completely flummoxed by direct sunlight. In 40 degree temps in France we kept experiencing odd drops of 3-4 degrees, eventually twigged that stray screenwash creates a drop in the measured temp as it cools the bulb by evaporation.
Windchill factor is a measure of comfort and how much more quickly body heat is removed in wind. It has no effect on an inanimate sensor.
|
|
Wind chill does not affect inannimate objects.
|
|
|
"Windchill factor is a measure of comfort and how much more quickly body heat is removed in wind. It has no effect on an inanimate sensor"
I shall prove or disprove that theory by swinging a thermometer around on the end of some string!
--
RF - currently 1 Renault short of a family
|
|
What about the centrifugal force on the mercury?!
|
An electronic digital thermometer then.
--
RF - currently 1 Renault short of a family
|
Wind chill factor relates to the amount of heat loss; for our small inanimate sensor that doesn't have it's own heat source this is irrelevant, whereas for a warm human being burning resources to try and maintain a constant temperature it is very relevant.
For info, read how to calculate both wind chill factor and wind chill temperature, here: ggweather.com/glossary.htm
|
|
|
|
RF - make sure the battery cover is firmly fixed, or you might take someone's eye out.
|
|
|
|
|
|
My 2003 V70 has an external temperature sensor mounted under each door mirror with the displayed value being the average of both. I suspect that this approach is far from unique.
|
I think the sensor on my Galant is under the bonnet or maybe even mounted on the exhaust. It seems to read several degrees higher than what I'd expect it to say, particularly in the summer.
----
Life is complex; it has real and imaginary parts.
|
|
On the Omega it's inside the front bumper above the fog light. Minus 6 on the way to work this morning, bit nippy for southern softies like me...
|
Around Baslow, Derbyshire it was ~-6C this morning ; always a frost pocket.
Passat sensor always sees to give consistent readings so I guess it is in a cool shady location.
--
I wasna fu but just had plenty.
|
My first car with one of these was a 1996 Holden Barina (Vauxhall Corsa in the UK), mounted behind the bumper and seemed to be very accurate when moving but less so when stationary for a long time. It had a very good range, I managed to check it down to -10C and up to +50C. It always agreed with a shade temperature and not a full sun temperature.
On combining multiple sensors, it is very easy to combine 4 sensors, ignore the highest and average the remainder so the sensor in the sun gets ignored.
StarGazer
|
I think on my A4 it is behind the lover front grille in front of the intercooler and radiator.
I have no reason to believ it isnt fairly accurate, and shouldn't be influenced by the engine temp.
|
|
Mine was reporting -2 this morning. Sounded a bit OTT (Or UTT, I guess), but the car was frozen so the general temp must've been below 0...
|
|
|
|
|
When the temperature really really drops the LCD displays in my car slow down and eventually stop
|
Don't know where it is on my Accord (on the Cavalier is was under the bumper), but what I do know is that when it drops to 3°C, the display on the dashboard flashes several times to let you know of potential black ice.
Andy
|
<< but what I do know isthat when it drops to 3°C, the display on the dashboard flashes several times to let you know of potential black ice.
Mine's even better ~ the display lights up and it emits a beep.
--
L\'escargot.
|
|
Don't know where it is on my 2001 Corsa, but I always find it really handy and I like the little snowflake that appears when its lower than +3 degrees.
|
|
LIkewise I find the one on my Renault very useful. It's very accurate as well.
|
Like most other Vauxhalls, the Astra's sensor is under the front bumper.
I would have thought that under the door mirror would give inaccurate readings as hot air from the air-con and/or coolant radiator comes out just behind the front wheels, on most cars.
|
Behind the bumper on my Range Rover.
--
\"Nothing less than 8 cylinders will do\"
|
|
|
|
|
