All work to be done by licensed professional. WE KEEP GOING UNTIL YOU HAVE THE INFORMATION YOU NEED, I come and go. This is step ONE.
Hello Ian, if it works in cooling mode, but not in heating mode, then the problem is one of its 5 micro processors (micro computers on board).... its very tricky business. Let me know a bit about you skill set with electronics or at appliance repair... I will know how to address this most effectively in that case for you.
Tell me what nation and city you are nearest, We can go from there.