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bclark
Date registered: Dec 1899
Location:
Vehicle(s):
| Outside temp reading query
Is the outside temp reading influenced by pavement and/or engine temp?
Does the outside temp reading influence cabin climate control?
Background:
Coming home from work in rush hour traffic on a Chicago
"expressway" at 6pm, with the air temp per weather report approx
60 F, my outside temp reading on the dash was 83 F. My heat
was set at 76 F in the cabin but was blowing cool air. As I
exited the expressway onto residential streets, the reading
fell to 72 F. Later in the evening, around 9 pm with the weather
report stating 53 F, my dash read 63 F.
Thanks |
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Ynot
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Outside temp reading query
bclark - 5/18/2006 9:22 PM Is the outside temp reading influenced by pavement and/or engine temp? Does the outside temp reading influence cabin climate control? Background: Coming home from work in rush hour traffic on a Chicago "expressway" at 6pm, with the air temp per weather report approx 60 F, my outside temp reading on the dash was 83 F. My heat was set at 76 F in the cabin but was blowing cool air. As I exited the expressway onto residential streets, the reading fell to 72 F. Later in the evening, around 9 pm with the weather report stating 53 F, my dash read 63 F. Thanks PM Shinigami, somebody else had the same problem and their temp sensor located somewhere in the front bumper IIRC dismounted from it's location and closed to the engine causing high temps, sounds like your problem. Shini could tell you where to look. |
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bclark
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Outside temp reading query
Thanks, I'll do that. |
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bloflin
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Outside temp reading query
Even when properly mounted, it can be influenced by the environment. Parking car on black asphalt in hot weather, it will register high until you drive for a few minutes, to allow the parts surrounded it to get back to ambient, for example. Conversely, spraying with water (as in washing your car) will lower temp for a few minutes.
Net: if you are driving (i.e. moving) for a few minutes (say 3 to 5) then it should register close to true ambient. If not, then it may have come lose and is too close or touching a part of the engine. |
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bclark
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Outside temp reading query
bloflin - 5/22/2006 2:06 PM
Even when properly mounted, it can be influenced by the environment. Parking car on black asphalt in hot weather, it will register high until you drive for a few minutes, to allow the parts surrounded it to get back to ambient, for example. Conversely, spraying with water (as in washing your car) will lower temp for a few minutes.
Net: if you are driving (i.e. moving) for a few minutes (say 3 to 5) then it should register close to true ambient. If not, then it may have come lose and is too close or touching a part of the engine.
That's what got my attention; even after 20 minutes on the road at 6 pm (road surface was not middle of the day
hot), it read 20 degrees hotter than the ambient temp. I'm having it checked this week while I get
a new engine dropped in. Thanks |
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bclark
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Outside temp reading query
Service guy says my sensor tests fine.
Humm. . . |
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Zut
Date registered: Dec 1899
Location:
Vehicle(s):
| RE: Outside temp reading query
I haven't tested the electronic thermometer while driving on hot downtown asphalt. On the motorway, however, I get extremely precise readings. Today, I went on a 300km ride and the temp displayed was 28,5ºC (on the radio, they said the temperature was between 28ºC and 29ºC). Last winter, I drove in freezing temperatures and the readings were still on the dot. There was no chill factor or engine heat interference. So far, I am very impressed with the quality of the instruments in this car.  |
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etyu
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Outside temp reading query
Is there anything near the outside temp. sensor that may be relecting heat to it? |
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bclark
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Outside temp reading query
etyu - 5/28/2006 8:22 PM
Is there anything near the outside temp. sensor that may be relecting heat to it?
Good question, etyu; nothing aftermarket. Today, Chicago hit 92 degrees F and my sensor
read 99 in residential, non stop-and-go traffic. The difference might be from reflected
asphalt heat (Zut, are streets concrete Montreal, which would reflect moreso than absorb
and radiate heat, in contrast to asphalt). The readings today made more sense than the
20 degree F difference last week. Somewhere I heard that temp sensors on performance
cars purposely reflect road conditions. Where is JULIEN when we need him?
Memorial Day weekend here has thusfar made for awesome SLK top down riding. Hope
all are enjoying and safely enjoying  |
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Zut
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Outside temp reading query
etyu - 5/28/2006 8:22 PM
Zut, are streets concrete Montreal, which would reflect moreso than absorb
and radiate heat, in contrast to asphalt.
I don't really know about that. There is asphalt everywhere but it may cover concrete in some places. The real acid test will be this summer when it is over 35ºC and the sun hits freshly rolled asphalt. The temperature at the street level can reach close to 50ºC in these conditions. Maybe then the reading will be a little off but so far, I had very satisfying results (on the motorway) in extreme cold weather and moderately hot temperatures (28,5ºC). I keep an eye on the temp display all the time and it always matches the official temperature ±1ºC. |
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SLK280DS
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Outside temp reading query
Word of warning. While checking my sensor I pushed on it just a little and it fell out of the socket that holds it. It's a pain to get back in the socket. You have to work blind thru the left wheel well opening. Unless you can get the car up on a lift and drop the lower engine panel to get to it. |
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bclark
Date registered: Dec 1899
Location:
Vehicle(s):
| Re: Outside temp reading query
SLK280DS - 5/29/2006 10:06 AM
Word of warning. While checking my sensor I pushed on it just a little and it fell out of the socket that holds it. It's a pain to get back in the socket. You have to work blind thru the left wheel well opening. Unless you can get the car up on a lift and drop the lower engine panel to get to it.
Thanks! |
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