Per the manual, when pushing the Auto button, the system automatically does it's thing (determine fan speed, airflow direction, A/C on or off.........).

Everytime I turn mine on (push the Auto button), regardless of the inside\outside temperature, the A/C comes on (green A/C light). I have to push the A/C button to turn it off.

Why?

 

Mine does that too, but just down to a temp of about 30 degrees. When the temp is below that and I start the truck it doesn't turn on the AC. Must be programmed in to keep the humidity down inside to prevent fogging.

 

That sounds about right. I know it acted goofy if I left it at 70. Now I put it in the 60 or mid 70s and it acts normal. Lately its been in the 20s here but when the temp spikes closer to 30 the AC light comes on. Sounds normal to me.

 

Sililar experience. If you read the manual on the defogging section it talks about using the a/c etc. so i think he's right, it is getting some of the moisture out before shutting off.