Is it possible to code the aircon system so that sync is remembered, so when restarting the car it defaults to this setting, rather than having to press the aircon switch and pressing the sync button on the head unit?

I reckon that Sync is actually remembered - just not displayed. That's how mine seems to work anyway; along with the niggle of having to use the passenger side (left) to adjust the temperature.

Thanks @SteveTheElder, I'll try this tomorrow 😀

Worked as described, sync not displayed but using the passenger controls the aircon was adjusted in sync, thanks 😀