HVAC has a mind of its own - Intermittent electronic issue

[Hans]

So the HVAC on the SSEi has been messed up from day one. It seems to be getting worse. I assume it is some kind of sensor or controller.

Basically all of sudden out of nowhere on a cold day it will be blowing very hot air thru both sides and then go to maximum coldness and the ac compressor turns on and everything even when it is 50* outside. If I "reboot the car" it goes back to normal for a while, anywhere from 5 minutes to a couple hours. It makes no difference if i turn the system off by pressing the driver side knob, same problem or play with the temp settings, same problem. I actually have to turn the car off and then turn it back on. Its random but the pattern has been increasing and I can pretty much reproduce the issue on every 30 minute or longer trip. When the issue occurs it will all of sudden go from "low" aka 2 bars of fan speed to maximum, even if the temp is set to 90* and the car is 70*, it will blow 40* air.

So I'm trying to figure out how the HVAC system works on this, specifically on the electronic end of things. I'm assuming there are at least two sensors for the inside temp, however maybe there is only one? Since it has dual climate control, I'd assume at least two, who knows where the sensor(s) are? Is there a master sensor and two other ones it gives a secondary priority to? Where are the other modules stored that manage the HVAC system? Hard to get to?

My guess of how the system works:
- Front control thing with knobs, buttons and display
- Sensor(s)
- Some kind of module somewhere or controller that pulls in the sensors and knob/display thing, maybe more than one.
- series of ducts and air doors that take signals from a module somewhere

So really, I think I just have a bad sensor or bad control module, since I can "reboot" the car and it comes back to normal, I just need some assistance in locating the parts and perhaps someone has a better idea of how the system actually works.

[flatlander745]

Mine "turns itself " on out of nowhere and sets to auto high...have much Bigger issues to deal with first, Lol.

[Hans]

hmm.