Does OBD or Forscan show Cabin temp?

[MrLoganRoss]

I am wondering whether any of the tools we have access to will show us the cabin temp, which presumably would influence the hvac system.

then of course, the question is whether one can program in an offset or calibration.

Thanks.

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[Runaway Tractor]

I am wondering whether any of the tools we have access to will show us the cabin temp, which presumably would influence the hvac system.

then of course, the question is whether one can program in an offset or calibration.

Thanks.

Yes it does. There are a few interior and exterior temperature sensors that are readable. No you can't change them. Unsure why you'd want to??

 

[MrLoganRoss]

I have some other threads where I discuss working through the hvac experience vs what the car offers (which is different than my Mache).
They just replaced the blower motor. Heating is better. I also just changed the cabin air filter.

The issue seems to be more about when it decides to heat (especially on Auto) vs whether the car heater is working. I am hoping to compare OBD to a legitimate scientific thermometer I bring into the cabin.

 

[Firn]

Car Scanner user here and was just monitoring this actually.

I'm using Interior Temp however don't expect it to read the "interior" temp, it seems more like raw sensor data.

What are you trying to do with an offset.

To be clear, "interior" temp can get pretty squishy. What a sensor measures the temp to be, and what we feel, are frequently different. Mostly due to things like sensor location and it's ability to measure what we are feeling. If you notice, there is no interior temp sensor hanging down from the ceiling between the front two seats, about the only place to get a proper temp.

 

[MrLoganRoss]

Yep. Tend to need to set the temp to at least 78

 

[MrLoganRoss]

When you say raw data, what do you mean? Thx.

 

[MrLoganRoss]

Car scanner is showing me internal temp

 

[astrand1]

Yep. Tend to need to set the temp to at least 78

You need to set it to 78 for what?

 

[TaxmanHog]

Yep. Tend to need to set the temp to at least 78

I've found 78° setting on the control creates a comfort level for our needs, can't say that it's accurate or not based on what the HVAC system is measuring as an input to cycle the PTC or VHP system to generate more heat.

 

[Firn]

When you say raw data, what do you mean? Thx.

There is a sensor to measure the interior temp, but where is it? It's not near the driver, so how does it know what the driver is feeling?

Generally there tends to be a sensor, or sensors, in the cabin. And from those sensors they determine what the driver is feeling.

When I say "raw" sensor values, it's what the sensor is reading but before any calculation to determine what the driver is feeling. Those calculations could be from the truck sitting in the sun for a few hours and the sensor is heat soaked. Or it could be in the cold, and the truck knows it's slow to update so it considers the BTUs it has been dumping into the cabin. Etc.

It could be a sensor on top of the dash. Or one in the air duct. Or in the center console.

Long story short, most every manufacture uses one or more sensors, but also applies various calculations or estimates on top of the sensor data.

 

[MrLoganRoss]

So it’s obviously not right near the driver’s head, but knowing how it reacts relative to how I feel lets me correlate. It’s in a spot where closer to the vents than I am.

I tracked it on the way home from a restaurant, including how it changes when I change the temp. It’s clear that at a certain point the system thinks it’s hotter than it is.

however, the info has been helpful and over the next few weeks I will test my ability to quickly adjust temp in a way that keeps me comfortable for the entire drive (harder as most of my drives are 20 minutes or less).

as a side note, my battery is at 100% health after being in service for 9 months.

 

[mrau]

FYI, the outside temp sensor is under the passenger side mirror. Not sure where cabin sensor is, but may look similar.

 

[Firn]

Fwiw the interior and exterior temp sensors look to have a precision of about 1.8 degrees.

 

[MrLoganRoss]

Ok, with access to Car Scanner and a decent scientific thermometer, and testing with an outdoor temp of 48 degrees, my test shows that the car’s interior temp deviates from the actual temp by being between 2 degrees and 4. 5 degrees higher (let’s call it an average of of 3-3.5 degrees).

That explains why I generally need to set the temp to 75 degrees.

To be fair, I think the scientific thermometer reacts slowly and so I want to rerun the test with a fast acting thermometer.

The goal is really just to recalibrate my thinking since it is taking a little more work to maintain temp. For example, when the car temp is 73, but inside the car is really 69, you feel the cold, yet the car is saying warm enough and stops heating.

when it heats it’s fine. The issue is getting it to heat consistently.

 

[Firn]

Here is a log of the heater power on a recent 1hr drive. This was for other purposes but it was at a controlled 70mph. Outside temp was ~20F and interior was set to 70.

Truck started from cold, leaving my 60 degree garage. The change in the middle was my halfway point and where I turned around. My guess is the truck automatically tries to account for thermal loss from traveling at highway speed, when I slowed down it didn't need to run the heater as hard.

You will notice that the interior temp was not changing, or at least the sensor value was not.

I watched the battery heater mode and it was off during the drive, the battery coolant inlet temp was also always cold. I do not believe that the heater was being used to heat the battery as it was warm enough.

Looks like the periodicity for the heater was about two minutes thirty seconds.