Here's SparkFun's CAN bus shield: https://www.sparkfun.com/products/10039.
It's not cheap, but it's from SparkFun so it's at least pretty in red. :) And, to be fair, it has a few nice features besides the CAN interface itself (SD card holder, LCD interface, on-board joystick).
The product comments mention this library for the software side: http://code.google.com/p/canduino/.
- if it's 35°C outside, I sure as hell don't want a/c to loop on 20°C
- if it's -15°C outside, I sure as hell don't want a/c to loop on 20°C
So basically what I want is:
- 16°C minimum (below produces too much condensation on the windshield, and is not comfortable on long-ish commutes ) - from 16°C at -10°C to 20°C at 20°C, maybe linear, maybe log, I don't know.
- and cap at 20°C max inside...
- ...but have a maximum negative delta of -5°C with the outside temperature (i.e 29°C outside means 24°C inside)
- yet with a true absolute maximum of 28°C inside
It's really not that hard and I could probably come up with a hack (has anyone plugged an Arduino into a CAN bus?) reading the inside and outside sensors, and controlling the temperature knob while reading its current setting from what the display shows, but damn, where is my car's SDK! Oh, the first world problems I have.