Eli5: How does a thermometer on a car work?

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I can’t think of a location within the bodywork of a car that would provide accurate data considering wind-chill when it’s moving, excessive heat from either the engine, or stationary in the sun.

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26 Answers

Anonymous 0 Comments

Generally, its located at the front, near the bottom. It can be influenced by the hear radiated from the road itself, so they are not super accurate and can run a few degrees higher than the actual temp

Anonymous 0 Comments

-Depends on the make, model and age. E46 BMW’s (1999-2005/6) get that info from the MAF (mass air flow) sensor that tells the ECU how much air, and what temperature it is, is going into the engine-

Disregard above, i am a dumbass

Anonymous 0 Comments

To be clear, windchill only factors in when something is warmer than the surrounding air, such as a human. Because a thermometer wants to end up at the surrounding air’s temperature, windchill enables the thermometer be more accurate.

So chances are that they’ll stick it wherever it gets consistent access to moving fresh air, so usually it’s in the front bumper before anything that heats the air up.

Anonymous 0 Comments

I’ve never seen an ambient car thermometer that is accurate. Here in Florida it gets hot, but usually never over 100. Yet most vehicles will say it’s over 100.

Anonymous 0 Comments

Wind just means something will reach the temperature of the air more quickly. One of the better places for it would be in front of the radiator, inside the grill.

The reason air movement helps people cool off even when the air is hotter than us is because we sweat.

Anonymous 0 Comments

Fwiw, cars don’t use thermometers they use thermistors. A thermometer works by mercury expanding or contracting due to temperature rising or falling respectively. A thermistor works by changing resistance in a wire based on temperature. As u/albigatin said, it is usually in the front and near the bottom, both of which shield it from ambient engine heat and with the idea that moving air will keep engine air away from it. This also keeps it out of direct sunlight. The problem is exactly what he said as well, asphalt roads especially trap heat and can be 40-50 degrees F hotter than air temperatures. Even in a moving car with the thermistor a foot higher than the road, the temperature will be a few degrees higher because of this. If your car is stopped, the temperature displayed will be even more skewed.

Anonymous 0 Comments

It’s called the thermostat. It’s a piece of metal that when heated to a certain temperature(boiling point essentially) a spring contracts, or expands I can’t remember, and acts as a valve essentially, allowing water to flow through the engine, with the assistance of a water pump driven by a belt, through the radiator and the rest of the engine creating a circulatory system of water that helps cool the engine. Combined with air flow over the radiator which water circulates through, especially with the radiator fan pulling air through when the car is not moving. This keeps the engine from overheating by allowing water to pass by and remove excess heat from the engine block.

Anonymous 0 Comments

Wind-chill is a strictly fake number designed to represent how cold the air feels because the wind is blowing. It’s not actually colder, but wind moving air, especially wet air, will “feel” cold because it rips the heat from your body faster than just the standing air would. It’s really no different than how you might have noticed 70 degree(F) air is comfortable/warm but 70 degree water can feel downright cold, it’s just that one is better at ripping the heat off of you.

So in that sense, wind-chill just means any thermometer subject to moving airflow will be more accurate faster, but would likely feel colder(or warmer) to human skin because human skin doesn’t really feel temperature but instead how fast it gains or loses heat.

Anonymous 0 Comments

Thermometers aren’t affected by windchill. Windchiil is a phenomenon where we ***feel*** temperature differently than what it really is, because what we feel is a sudden inrush or outrush of heat from our body, or the inability of our body to shed excess heat… not the temperature itself.

For example, when you touch a seatbelt buckle in a car that has been sitting out in the sun, it feels searing hot, but it’s really only around 140°F, and if you could use a good temperature measuring device like a thermocouple to try to measure its temperature, you would indeed get around 140°F. It just feels searing hot because metal is very good at conducting heat.

Anonymous 0 Comments

Its not mega accurate doesnt have to be, wind chill isnt temperature its just wind. It Will probably be placed somewhere Away from hot parts that gets Airflow likely in the front. On my car its in the front left brake cooling duct between the Wheel well and the front bumper.