Where is the "A" ambient temperature reading coming from, on the MK3S?
I have installed OctoPrint with the MQTT addon, and getting lots of data from the printer.
As well as the bed and tool temps, I am also getting "P" and "A" temperatures. A quick google leads me to believe these are "Pinda" and "Ambient" temperatures.
After some monitoring and testing, whereby I open and close the doors of my enclosure, the "A" temp does seem to reflect the temperature within the enclosure. (I don't have a dedicated enclosure sensor, so I can't really compare with real values, besides - it would depend on where the sensor is located.)
So - is this "A" reading indeed supposed to be measuring "ambient" temperature, and if so - where exactly is the sensor located?
RE: Where is the "A" ambient temperature reading coming from, on the MK3S?
The sensor is on the main board pcb. So you are reading the temp there. Pcb mounted temp sensors are not very accurate and rarely reflect the actual ambient temperature. Not just on the printer, I also mean in general. Most pcb's are mounted in enclosures and the actual pcb components also generate heat.
Its even worse if the temp reading in internal to the microprocessor (some micro's have built in temp sensors). Those are always warmer. Often by quite a margin.
RE:
Yes, you're right. Those sensors may be fairly accurate, but they don't give us a clue of the real ambient temperatures. Based on my experience with a MK3S, I'd expect readings of 50-60C on the PCB board when the printer is working and an ambient temperature of 20-25C. Even on a idle printer the main PCB is always quite warm (40C at least).