The temp showing on the EVIC in my 08 Aspen seemed to take forever to change -- sometimes 20+ minutes before it would adjust to the correct temperature, which seemed to also be affecting the automatic temperature control. I found the temp sensor online ($7), and it took five minutes to install it. Everything is working correctly again. Just FYI for anyone having this problem.

The sensor is in front of the radiator, and is easily accessed if you remove part of the black plastic fan/radiator shroud and reach down. It's held on with a simple pressure clip -- no screws.

 

Thanks for the info!