My 2000 GC limited has a problem with its air con/heating. It cant seem to regulate the temperature. One minute its nice and warm, then it will start to blow cold air, turn it up a few degrees and it gets hot again. I have removed the blend door motor and checked the stops are present on the blend door (the one I can see) I had some errors on the aircon but they cleared and have not come back.
The car has the dual zone heating system with seperate controls for driver and passenger side. Both sides seem to do the same.

Any thoughts?

Thanks