Model S AC Sensor Calibration

[Thomas Allen]

Over the last few years I’ve found that I’ve had to set the interior temperature lower and lower in order to keep my AC’s fan blowing in the Auto mode. I currently need to set the control to 64 degrees in order to maintain 72 degrees inside the car. If I set it above 64 degrees it blows cold air, but at a very low fan speed. Has anyone else had, and resolved this issue? (2014 Model S)

 

[BrownOuttaSpec]

I haven't but you might want to check what the car thinks the temp of the air is blowing out of the vents with something a cable to your diag port, a bluetooth module and an app like ScanMyTesla.

You could check a couple of maintenance type items too

• Maybe unrelated but have you checked/changed your cabin air filter? Maybe it is clogged and not getting good air flow.
• Also it could be that your A/C system has a small leak and needs to be recharged after 9 years of service so it isnt performing at 100%.
• Front Louvers near the fog lights opening normally? Those are used for AC and it wont perform correctly if they dont open properly.

 

[Thomas Allen]

The Cabin filter is clean and the ac was serviced by Tesla 2 years ago. What’s odd is the fan slowing down. It’s as if the system believes the the correct temperature has been achieved and it goes into the low speed fan-temp maintenance mode. The air is cold, but the calibration is off by 8 degrees.

 

[BrownOuttaSpec]

Do you have the AC vent pointed at the sensor area or a cold drink sitting in front of it? Someone had the opposite experience by covering the hole with their hat: Friendly tip -- Don't block the cabin air sensor!

I've never heard of a way to reset or calibrate it but maybe someone else has. Unless you have the data from the car itself it's hard to tell what data the car is getting. At the end of the day maybe you need a new sensor and a little DIY skills:

Here is a video showing the location and the removal and part number (6007376-00-B):

Here is a video with generic sensor information but they show how to test it:

 

[PCMc]

A few thoughts.

Have you confirmed that range mode is not enabled? This might be allowing a larger error between your desired temp and actual to try and minimize energy use by the HVAC system.

Have you used the app on your phone to see what it reports as the interior temperature when you are seeing the large 8-9 degF delta in set point and actual temperature? It the phone is suggesting that interior temperature is much colder than what you are able to measure with an independent device, this would tend to support hypothesis that somehow the sensor is not tracking well.

I recall there is an ambient light sensor on the dash. I don't know this for absolute fact, but many vehicles will also use that as an input to HVAC auto controls, both in terms of which vents to bias airflow but also potentially fan speed. If this sensor is getting shaded so it's not sensing the true level of solar gain, this could also be messing up fan speed auto selection. Have you recently done something like tinted the windshield or maybe started placing a cap on the dash which could be covering or shielding this sensor?

 

[vcor]

I'll also add that in most years (perhaps not 2012-2013?) the temperature sensor includes a tiny fan to pull air across the sensor. It wouldn't surprise me if after 9 years this fan has failed, so it can no longer reliably detect the cabin temperature. In the BrownOuttaSpec post above, the first video shows the sensor location up through 2021 LR+/Performance.

On the 2021+ LR/Plaid the sensor and fan are moved to just above the phone chargers.