2013 Chevy Malibu cooling issue

I have a 2013 Chevy Malibu with just over 64K miles. Last week, my temperature gauge stopped working and I got a message that the A/C had stopped working due to high temperature. I got this notification even if I started the car before dawn in 20 degree weather. I had the cooling system checked at a chain store, and the thermostat replaced. I didn't even make it off the lot before the check engine light came on again. I backed up amd took it back and the techs checked the error code and drove it around. The engine light turned off and everything was fine. This morning while driving home from work, the engine light came on again and I got the exact same message about the A/C being off due to high heat. I didn't smell any antifreeze, and the air coming out of the heater wasn't any hotter then normal. Other than a thermostat not installed right, what could this possibly be?