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Outside Temperature Readings

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Copied this from the 2016 Forum regarding speed sensitive outside temp reading.  Here's the copied text... *UPDATE*  Ok I've been running tests.  The speed limit in my development is 25MPH.  The side road to the Library is 35MPH.  The Main road from the Library to the major artery is 40MPH.  As an example, on one test my temp reading was 79 degrees and on all the roads it continued to read that, even though it was really 93 degrees.  Not until I reached 45-50 MPH 5 miles later did it jump 14 more degrees to 93.  I just had an oil change so I asked the technician.  Before I full described whats happening he said, "Yep, I have an Ford Edge and 40 MPH is the speed that you must exceed for a proper reading".  So now I guess in order to determine the temp I'll have to speed, risk a ticket, possible an accident and definitely hurt my MPG average by hot-dogging it thru town.  Ford/Lincoln, seems like some Engineers need to go back to school on this one!

 

​The question I have....those with a 2017 model, is this an issue or has Ford/Lincoln ractified?  It drives me nuts.....

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More precisely, you're the one who's ractified; Ford/Lincoln being the source of the ractifing stimulus. :chacha:

 

I can only offer an opinion. If they require you to hit 40 mph, it "may" have something to do with making certain that the engine has reached normal operating temperature, and, that the fans are not on. The air temperature being taken from the air entering the engine.

 

As to the purpose, I'd hesitate a guess that your seeing what the computer is reading, not warmed up = run closed loop engine program until specified temp are reachef, then open loop.

Edited by enigma-2

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It has to get residual heat from the engine and/or sun baked parts away from the sensor before you can get an accurate reading. Perhaps they could have chosen a better location or design but the programming is to prevent false high readings which would cause a lot of folks to take it to the dealer.

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More precisely, you're the one who's ractified; Ford/Lincoln being the source of the ractifing stimulus. :chacha:

 

I can only offer an opinion. If they require you to hit 40 mph, it "may" have something to do with making certain that the engine has reached normal operating temperature, and, that the fans are not on. The air temperature being taken from the air entering the engine.

 

As to the purpose, I'd hesitate a guess that your seeing what the computer is reading, not warmed up = run closed loop engine program until specified temp are reachef, then open loop.

 

Ractified??  Darn spell check changed this from rectified and changed it twice.  

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It has to get residual heat from the engine and/or sun baked parts away from the sensor before you can get an accurate reading. Perhaps they could have chosen a better location or design but the programming is to prevent false high readings which would cause a lot of folks to take it to the dealer.

But if doing local "chores" you could go for miles and miles with false readings.  I could live with a mile or time parameter but speed seems non-sensical.  Other manufactures don't seem to have this issue. 

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Ractified?? Darn spell check changed this from rectified and changed it twice.

Ah. But "ractified" is actually a word.

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But if doing local "chores" you could go for miles and miles with false readings. I could live with a mile or time parameter but speed seems non-sensical. Other manufactures don't seem to have this issue.

Completely agree. On my n 09 I get reading immediately after startan (even if wrong).

 

Speed only seems to make sense if you consider air flow through the radiator. At slower speeds the fans may be running. At some point, there's enough air flow to cool down the coolant and the fans are off. (Still just a guess).

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I think the root problem is the placement of the sensor and/or the type of sensor and all the programming is a workaround for the engineering screwup.  You should not have to hit 40 mph to get an accurate reading.   I was just explaining why they had to program it like that, not saying it should work that way.

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I think the root problem is the placement of the sensor and/or ...

Don't think it's the placement. It's behind the grill, below the right headlight. As it detects the correct temperature after reaching 40 mph, it's location can probably be ruled out. Has to be programming.

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"Outside Air Temperature Display

 

The AAT sensor is hardwired to the PCM through separate input and return circuits. The PCM provides a reference voltage to the AAT sensor and monitors the change in voltage resulting from changes in resistance as determined by outside air temperature. The PCM messages the outside air temperature data to the HVAC module through the BCM . The HVAC module filters the temperature data and sends the updated temperature status back to the BCM . The BCM in turn messages the outside air temperature in degrees Celsius (metric) to the IPC . When the Fahrenheit (English) display is selected by the driver, the IPC converts the Celsius to Fahrenheit and displays the temperature in the message center.

 

The HVAC module is programmed to update the messaged outside temperature data at different rates depending on several criteria to prevent false temperature displays due to a condition known as heat soaking. Heat soaking is where the air temperature in the location of the AAT sensor is hotter than the actual outside air temperature.

 

When the sensed outside temperature rises, the display updates slowly at varying rates based on vehicle speed. When the sensed outside temperature drops, the display updates more quickly following the drop experienced by the AAT sensor."

Edited by enigma-2

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If the real problem is no a/c during false reading, others reported putting the a/c in recirculate and this (appearently) forces the temperature in MFT to "LO". Another person state he put his hvac control to "MAX" in order to gain control and get the a/c working.

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Hitting the Max A/C button or just turning the temp all the way down to LO puts it in Max A/C mode which should override everything.

 

My point on location was that perhaps the current location produces more heat soaking which then had to be compensated for by delaying the updates.  Had they chosen another location not so susceptible to heat soaking the software wouldn't have to delay the updates as much.   Especially since other brands don't seem to have the same issue.

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