HVAC either hot or cold. Almost no in between.

[Buford T Justice]

I have a 2013 3.8 with about 130k on the odometer.
My HVAC only offers extreme temperatures.
If I turn on my AC it will blow ice cold air from low - 65 degrees f.
66-76 degrees just blows ambient temperatures.
76-78 blows warm air and 78 - high blows as hot as it gets.

What would cause this?
If it was a blend door stuck or something I would just get hot or cold, not both with nothing I between.

If I put the climate on "auto" it will just give up and turn the fan down really low instead of trying to make it whatever temperature I set it on.

 

[joegr]

Maybe your cabin temperature sensor is bad, or maybe one of the air outlet temperature sensors. It's all wild guess work without hooking up some tools and seeing what readings the climate control system is getting.