Air Con now has a mind of its own!

After I had my compressor replaced a couple of weeks back my air con has started to act a bit 'odd'.

I first noticed this when I turned it off last week while driving home from work & it remained on & wouldn't switch off. When i turned the engone off & restarted it was fine again (responded to the AC button)

A few days after that, I was driving around town & it switched it self on all by itself - i hadn't even used it that day.

Then today, it came on when I started the car then turned off. Again, I didnt press the aircon button.

Could it be the heater control panel be playing up or does anyone have any other ideas?

Thanks.