After a quick consultation with my buddy, it appears that there was some miscommunication.

The t-stat is actually about 4 or 5 years old, not 11 months like I originally thought.

Possible it's sticking closed too long and only opening at much higher temps?

 

Replace the t-stat, when they go bad typically they stick open, but they can stick closed or not open all the way either.
Using the a/c dumps alot of extra heat infront of the radiator so a stuck t-stat will cause overheating.