2012 Fiat 500c only blowing hot air when temperature adjusted

Recently the weather has started warming up and I noticed when adjusting
the temperature I only have hot air blowing out all vents.  This occurs even
when selecting AC.  I suspect it could be the door that would blend outside
or AC air so perhaps a faulty actuator.  I have not heard any sounds that
would indicate an issue, just hot air.  I checked the coolant level and that
seems okay.  I did notice also that the temperature gauge for the engine is
slightly higher than I think I have seen in the past ( gauge rises to
approximately half way and I think it was one bar lower previously )   I will
hunt for the door actuator as I can't find anything online that shows this fix
exactly but hoping it is simple enough.  I did change the cabin filter last fall
so not sure if I did something when changing that out.