# Outside themometer inacurate?



## SilverCruzer (Nov 30, 2010)

Not a deal breaker by any means, but has anyone else noticed the outside themometer being off? From what I noticed, it seems off by about 3-5 degrees.
I am aware of the service bulletin regarding the time delay of udate after frist starting the car, but I noticed its still off when driving for some time. For example, on my way home from work it stated 33 degrees as I pulled into the driveway. My house oustide digital themometer (in the shade) stated 28 degrees.
Again, not that big of a deal, but my previous older cars were more accuarate, and when the season (now) is quite often right around the freezing point, a few degrees says a lot.


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## Inline4_driver (Jul 23, 2010)

There's a lot of factor that could be affecting this. All my cars that had outside temp sensors would always be off by a couple degrees. Depending on where they positioned the engine heat could be affecting it. Also the head wind could be affecting it too. I wouldn't trust any one of them to be accurate plus all you need to do to properly gauge the temp is open the window and check very quickly with your hand.


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## Sour Kruat's 951 (Nov 9, 2010)

I also had this problem with mine. 

I installed the foglights so I had to disconnect the battery. After the battery was re-connected and everything was reprogrammed in the car it started the outside temp, among other things, started to work much better. This is a YMMV since I have not heard of anyone else doing a battery reset yet. 

The service manual did not mention this, but it does mention several of the items that need to be reprogrammed after a battery disconnect. Like the auto windows and such. 

Nothing directly pointed to the temp reading but this was my experience.


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## racer114 (Nov 7, 2010)

I have four of these thermometers in my vehicles and they are all off. The worst is the Chrysler product, it is off typically by 5-8 degrees. The Fords are close, +/- 1 degree and the Cruze is 3-4 degrees optimistically high.


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## cruze-control (Jul 23, 2010)

70AARCUDA said:


> ...with the "funky" way they (Chevy) have the computer read & display the thermometer sensor values (speed dependant?...WTF?), I, too, doubt the accuracy of what I see.
> 
> ...however, since I do have a couple spare remote TEMP / HUMIDITY sensors in the garage for our home weather station. I think that I can tape one adjacent to the car's thermistor sensor and record the results. Since this remote sensor is calibrated at ±1°F, I should be able to get a meaningful answer.


wow! i didnt know it was speed dependent. why would they do that though? to compensate for the wind chill factor??


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## SilverCruzer (Nov 30, 2010)

cruze-control said:


> wow! i didnt know it was speed dependent. why would they do that though? to compensate for the wind chill factor??


I believe the reason for this is the faster you drive, the quicker the air gets displaced around the sensor. Say for example, your car has been sitting in a 45 degree garage. You then pull out and drive around your 'hood at 15 mph, the outside colder air is going to take a while to "flush" the warmer garage air away from the sensor. If you jump right on the interstate however, faster air will flush the warmer air away faster.
It's my best guess.


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## cruze-control (Jul 23, 2010)

both explanations sound good to me. lol. one of my cars doesnt have that feature. when im parked indoors and drive outside it will display around 25-30 degrees celsius for the first few minutes then it will slowly go down to the proper temp which is around 1-5 degrees celsius.


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## ALiCE (Jan 15, 2011)

*EUROPEAN CRUZE*
In my user manual it states:
"Temperature drop is indicated instantly and the rise of the temperature is indicated with a *SHORT* delay".

The problem with the temperature display began after a software update to address another problem, the "transport mode".

Now, here comes my opinion, the above were certain facts:
Anyway, because they couldn't solve it after a year (!!!!!!) they issued the update about how the temperature is updated - trying to transform it into "it's not a bug, it's a feature".

Now, the temperature display is not such a big problem BUT the automatic climate control depends on that too, among other things. So an inaccurate display of the outside temperature translates into an inaccurate setting of the in-car temperature.

Because I pursued them to fix the temperature display, they did it to my car! They changed the BCM, did a software update and (at least for now) the temperature is shown corectly.


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## ALiCE (Jan 15, 2011)

It may be a way of solving it, if it really doesn't work as it should.
If the outside temperature drops during a trip, but the temp displayed doesn't (check with a termomether), then yes, it is defective.


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## montgom626 (Jan 16, 2011)

ALiCE said:


> *EUROPEAN CRUZE*
> 
> 
> Now, the temperature display is not such a big problem BUT the automatic climate control depends on that too, among other things. So an inaccurate display of the outside temperature translates into an inaccurate setting of the in-car temperature.


My AUDI A8L is off by 2-3 degrees. Who cares? Why care? If you need the temp gauge to tell you if you are "comfortable" in your car, then you have bigger issues that the gauge. If 75 makes you happy, select 75. If 79 makes you happy then select 79.


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## ALiCE (Jan 15, 2011)

I PAID for a WORKING AUTOMATIC climate control.
Normaly, I should set it to about 23 degrees and forget it.

It's not about a constant difference 2 or 3 degrees.
If outside were 30+ C and the display showed 14C, with the temperature set to 21C, i were sweating!


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## montgom626 (Jan 16, 2011)

ALiCE said:


> It's not about a constant difference 2 or 3 degrees.
> If outside were 30+ C and the display showed 14C, with the temperature set to 21C, i were sweating!


I am not so sure that the outside temp controls the inside temp 
I always imagined the outside thermometer measured the outside and did not influence the temp control for the interior. 

I have never done it, but can't I set the temp to 85 F for the interior when the exterior is 30 F and also when the exterior if 100F?

How does the thermometer for the exterior influence the setting for the interior and/or the output of the heater or A/C?

Anyone know the answer?


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## ALiCE (Jan 15, 2011)

If you set the interior temp for 85F, when the outside is 30F, it should blow *hot* air inside.
If you set the interior temp for 85F, when the outside is *100F*, it should blow *cold* air inside.

BUT if you set the interior temp for 85F, when the outside is *100F*, and the read temperature (displayed on the dashboard) is *30F*, it will be messed up and it may blow *hot* air inside.


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## montgom626 (Jan 16, 2011)

ALiCE said:


> If you set the interior temp for 85F, when the outside is 30F, it should blow *hot* air inside.
> If you set the interior temp for 85F, when the outside is *100F*, it should blow *cold* air inside.
> 
> .


You are right. My 2LT allows me to turn off the A/C . If it is 80F outside and I set my temp to 85F I will get 85F from my heater (call me crazy). Now, if I set my interior temp (no A/C) at 55F, I will get a warm 80F blowing into my face and sweaty armpits 

My question is, does anyone know if the external temp gauge has any influence on what my interior car thermostat does????? I can't see how it does or why it would even try. I always assume that the interior temp gauge controls my interior temperature. And that the exterior temp gauge just passively reports the exterior temperature to some digital gauge on the dash. If I set my interior temp to 70F, and it is 10F outside and 10F inside the car (before the car starts) then my heater will pump out heat until it hits 70F in the inside of the car raising the interior temp from 10F to 70F (up 60F) and then slow down, only providing heat to the interior when the interior temp drops below 70F. The car heater does not "know" and does not "care" what the outside temp is. It only responds to the interior temperature. The exterior temp gauge doe not report the exterior temp to the interior temp control at all. Why would it?

HELP


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## TSURacing (Jan 1, 2011)

It may use it to determine when to use recirculate and when to blow outside air in.. No data on that, just a guess.


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## wolfpack86 (Jan 26, 2011)

Here is my guess. 

There is no sensor on the car specific to the outside temperature. Instead they use the reading from the MAF, as this would be free. The MAF is located directly above your engine which means it can become "heat soaked". Therefore the vehicle has no way of knowing the actual temperature until the vehicle is moving and air can flow throw the intake and cool the MAF to the ambient temp. The only way to fix the issue would be to install a temp sensor far away from the engine, and lets face it for a <$20,000 car no car company is going to do that.


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## ChevyMgr (Oct 27, 2010)

*Here's how it really works.*

In automatic operation, the HVAC control module maintains the comfort level inside of the vehicle by controlling the A/C compressor clutch, the blower motor, the air temperature actuators, mode actuator and recirculation actuator.


To put the HVAC system in automatic mode, the following is required:
The auto switch must be activated.
The air temperature switch must be in any other position than full hot or full cold position.
Once the desired temperature is reached, the blower motor, mode, recirculation and temperature actuators automatically adjust to maintain the temperature selected. The HVAC control module performs the following functions to maintain the desired air temperature:
• Monitors the following sensors:
- Ambient air temperature sensor
- Lower left air temperature sensor
- Lower right air temperature sensor
- Upper left air temperature sensor
- Upper right air temperature sensor
- Windshield temperature and inside moisture sensor
- Ambient light/sunload sensor
- Air quality sensor
• Regulate blower motor speed
• Position the air temperature actuator
• Position the mode actuator
• Position the recirculation actuator
• Request A/C operation​ 
When the warmest position is selected in automatic operation the blower speed will increase gradually until the vehicle reaches normal operating temperature. When normal operating temperature is reached the blower stays on high speed and the air temperature actuators stays in the full heat position.

When the coldest position is selected in automatic operation the blower stays on high and the air temperature actuators stay in full cold position. The mode actuator remains in the panel position and the recirculation actuator will remain in the recirculation position.

Under cold ambient temperatures, the automatic HVAC system provides heat in the most efficient manner. The operator can select an extreme temperature setting but the system will not warm the vehicle any faster. Under warm ambient temperatures, the automatic HVAC system also provides air conditioning in the most efficient manner. Selecting an extreme cool temperature will not cool the vehicle any faster.
The HVAC control module evaluates the information of the air quality sensor and closes the recirculation flap while the air quality sensor switch is pressed, as soon as the concentration of pollutants exceeds a predefined value.

In automatic mode the values of the windshield temperature and inside moisture sensor are used as control inputs for the HVAC control module application to calculate the fog risk on the passenger compartment side of the windshield and ability to reduce fuel consumption by decreasing A/C compressor power to a minimum without causing any fog. The A/C compressor and the defrost mode are activated to prevent or remove fog on the passenger compartment side of the windshield. The sensor will also enable partial recirculation mode in order to improve heat-up performance of the passenger compartment under cold ambient temperature conditions without the risk of mist build-up on the windshield.


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## ALiCE (Jan 15, 2011)

a) There IS a temperature sensor, located in the front bumber, in the left side of the car, in the fog light space.
b) The MAF usually can't have a temperature close to the outside temperature (because of the turbocharger, intercooler, etc). Also, the temperature is about the same, with the engine started, regardless if the car is moving or not.
c) GM Romania told me that "automatic climate control" is using the outside temperature, among other things like sun load, light, air quality, etc.


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## ChevyMgr (Oct 27, 2010)

The outside temperature sensors only function is to display the outside temperature. It has no effect on the Auto A/C.

edit: I'm wrong, it does figure into the settings. Most GM vehicles have a sensor inside for this, usually in the headliner, but the service manuals says the Cruze uses the outside sensor.


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## wolfpack86 (Jan 26, 2011)

ALiCE said:


> a) There IS a temperature sensor, located in the front bumber, in the left side of the car, in the fog light space.
> b) The MAF usually can't have a temperature close to the outside temperature (because of the turbocharger, intercooler, etc). Also, the temperature is about the same, with the engine started, regardless if the car is moving or not.
> c) GM Romania told me that "automatic climate control" is using the outside temperature, among other things like sun load, light, air quality, etc.


I was thinking of the non-turbo Cruze. Even on the 1.4L TC there is still a sensor after the air filter box, i believe is temp (which would mean the CAC and turbo have no bearing on the temperature).
I am not real familiar with GM's sensors but I do know I have seem many airflow sensors get heat soaked under the hood.
I had read that sensor on the bumper (fog light area) was to turn the automatic lights on and off. If you care to check just unplug it and see if the lights or the temp are affected.

Any GM guys that can confirm this sensor is indeed for the outside temp?


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## ALiCE (Jan 15, 2011)

After they changed the BCM, we took the car outside. The displayed temperature began to drop.
To accelerate the process, I put some snow on the sensor in the fog light area. The temperature dropped rapidly to about 1 degree Celsius.

For turning on/off the automatic lights, the sensor on the dashboard is used (the one in the middle of the windshield ventilation, that also has the red led for alarm and a sensor for the inside temperature).


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## wolfpack86 (Jan 26, 2011)

ALiCE said:


> After they changed the BCM, we took the car outside. The displayed temperature began to drop.
> To accelerate the process, I put some snow on the sensor in the fog light area. The temperature dropped rapidly to about 1 degree Celsius.
> 
> For turning on/off the automatic lights, the sensor on the dashboard is used (the one in the middle of the windshield ventilation, that also has the red led for alarm and a sensor for the inside temperature).


Good test, then I am wondering if the issue was as described earlier, the CAC and radiator were heat soaking the sensor (during development) and causing it to read very high. I know this type of algrorithm has been around since the Cobalt was rolled out. I am wondering why it is just now becoming a problem. Hope they come up with a calibration fix to help you out


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## TSURacing (Jan 1, 2011)

ChevyMgr said:


> The outside temperature sensors only function is to display the outside temperature. It has no effect on the Auto A/C.
> 
> edit: I'm wrong, it does figure into the settings. Most GM vehicles have a sensor inside for this, usually in the headliner, but the service manuals says the Cruze uses the outside sensor.


Thanks for the write up on how the Auto A/C system works. I have one question though. I notice that the AC light is always on when in Auto mode. Does this mean the compressor is aways engaged?
Even at reduced power I think it may have fuel mileage implications if it is ALWAYS on. Or is the light on just to say that the system will be turning it on and off as necessary.


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## montgom626 (Jan 16, 2011)

TSURacing said:


> Even at reduced power I think it may have fuel mileage implications if it is ALWAYS on. Or is the light on just to say that the system will be turning it on and off as necessary.


I always turn off the headlights and turn off the A/C assuming I don't need either. Does it save gas? Improve mileage? I don't know. I can't imagine it makes mileage worse? 

I know the headlights should last longer with them being off.


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## ALiCE (Jan 15, 2011)

With AC I agree, but I preffer to change bulbs if that means that I can be seen better in traffic.


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## montgom626 (Jan 16, 2011)

ALiCE said:


> With AC I agree, but I prefer to change bulbs if that means that I can be seen better in traffic.


Another case where "logic" does not agree with reality. The DRL studies were done in Scandinavian countries. Long, dark winters. NO study has ever been done that says that DRL make a bit of difference in road safety anywhere else. 

I am smart enough to know when I need to turn on my headlights. rain, darkness, fog, snow, etc. Running headlights at high noon in the middle of summer is not one of those times. I am smart enough to know to wear my seat belts. I am smart enough to know that passing on a blind curve is a bad idea. I am smart enough to know that running a red light is a bad idea. Running my headlights at noon in July just does not make the cut.

DRL is a "religion". I have nothing against a belief in a god, higher power, DRL, etc. Just don't tell me DRL are proven to work in any place but Scandinavian countries, as there is zero data to support that idea. Never been studied. 

Science told us years ago that blood letting was a good idea. Time has shown it is a bad idea. But blood letting was standard of care for doctors for a long long time because folks "believed it worked. Just like DRL, it was "proven". Too believe otherwise was "heresy".

DRL is "blood letting" cloaked in a new science. But if you believe in DRL, then I will not stand in the way of your "faith".

Science showed for decades that smoking did not cause disease.  Same science that says that DRL saves lives. NONSENSE


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## montgom626 (Jan 16, 2011)

A 2008 study by the U.S. National Highway Traffic Safety Administration analysed the effect of DRLs on frontal and side-on crashes between two vehicles and on vehicle collisions with pedestrians, cyclists, and motorcyclists. The analysis determined that DRLs offer no statistically-significant reduction in the frequency or severity of the collisions studied

FWIW


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## montgom626 (Jan 16, 2011)

*Effect of ambient light*

The Daytime Running Light was first mandated, and safety benefits first perceived, in Scandinavian countries where it is frequently and persistently dark during daytime hours in winter time. As ambient light levels increase, the potential safety benefit decreases while the DRL intensity required for a safety improvement increases. The safety benefit produced by DRLs in relatively dark Nordic countries is roughly triple the benefit observed in relatively bright Israel and America.


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## ChevyMgr (Oct 27, 2010)

TSURacing said:


> Thanks for the write up on how the Auto A/C system works. I have one question though. I notice that the AC light is always on when in Auto mode. Does this mean the compressor is aways engaged?
> Even at reduced power I think it may have fuel mileage implications if it is ALWAYS on. Or is the light on just to say that the system will be turning it on and off as necessary.


Yes if the light is on the A/C is on.

If you have the automatic air, you can do some personalization using the config, but I don't think this is one of the things you can change or adjust.


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## ALiCE (Jan 15, 2011)

Not true 
The light may be on without the AC compressor being engaged. (ex: too cold outside).
Also, the AC compressor may be engaged with the light being off.

I'm talking about automatic climate control.

Now, about the DRLs:

I won't argue with you.
BUT: as long as running with the lights on *MAY* improve the safety and doesn't have any disadvantages (fuel economy is too small to count), I will keep them on.
Also I was talking about the headlights (short beam), not DRLs.


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## ChevyMgr (Oct 27, 2010)

ALiCE said:


> Not true
> The light may be on without the AC compressor being engaged. (ex: too cold outside).
> Also, the AC compressor may be engaged with the light being off.
> 
> I'm talking about automatic climate control.


I didn't say anything about the compressor running with the light off, but you are right it does come on in certain modes with no indication from the light. 

As far as the question is the A/C on when the light is on, yes it is. Just because it cycles off doesn't mean it won't come back on too, during cold ambient temperatures.

I like you ALiCE, you are going to be a fun poster for sure.


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## ChevyMgr (Oct 27, 2010)

I don't need any studies to tell me that I have a better chance of being seen with lights on than with lights off.

Safer? Who knows, but I am pretty sure DRLs have never caused a crash. I could be wrong.

And that being said, lets get back on topic with Outside Temp as this thread started out. Anyone can create a DRL thread and we can all comment in it. Thanks.


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## stowbilly (Apr 24, 2013)

My 2012 LT just started reading 69 F for the outside temp, even though it has been in the 90`s the last few days. Taking it to dealer in 2 weeks (Backed up because of recalls).The Service Manager told me it doesn`t effect anything performance wise, it`s just an outdoor temp indicator. But after reading this, I`m not so sure the Service Manager is right. I wonder if this has anything to do with the AC buzzing after I turn off the car?


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## obermd (Mar 3, 2012)

stowbilly said:


> My 2012 LT just started reading 69 F for the outside temp, even though it has been in the 90`s the last few days. Taking it to dealer in 2 weeks (Backed up because of recalls).The Service Manager told me it doesn`t effect anything performance wise, it`s just an outdoor temp indicator. But after reading this, I`m not so sure the Service Manager is right. I wonder if this has anything to do with the AC buzzing after I turn off the car?


I think during the summer your Service Manager is correct. However, the car uses this in the winter to help protect the A/C compressor during freezing conditions.


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## spacedout (Dec 7, 2010)

I wondered about this the other day as when I wash my car and its reading 80-90F, I pull out of the car wash its in the 60F range. Using the torque app looked at intake temperature, it was reading within 3 degrees above outside, same as always. Definately a separate temperature sensor & doesn't seem to effect the engine at all. 

I park in the sun most of the time that outdoor sensor will read 10-15F high for the first couple miles of my drive usually.


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## Jim Frye (Mar 16, 2011)

On my car, you can adjust the outside temperature sensor by +/- 5 degrees F via the display (DIC in the Cruze). I found mine to be off by 2 degrees, both with the engine off and idling outside using an IR thermometer.


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## Dragonsys (May 27, 2013)

spacedout said:


> Definately a separate temperature sensor & doesn't seem to effect the engine at all.


It is in the front bumper cover by the driver's side fog light (or the plastic cover if you don't have fog lights).


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## Chevy Customer Care (Oct 29, 2011)

Hi stowbilly,

I understand that you are experiencing some difficulties with your Cruze and that you will be taking it to your dealer for your temperature concern. If needed, we are here to speak with your dealer on your behalf. Feel free to send us a private message in regard to your concern if any extra help is needed!

Kristen A.
Chevrolet Customer Care


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