I found out that the condensation line was clogged. My system has the aquaguard ag-3000e and I notice the red light was on. This the second time this happens to me. First time I left the porch door open for too long. And this time was the garage door. Even that I had the door closed it still clogged the line. I was able to fix it by using a shop vac. Once the line was cleaned the thermostat started working. I even bought the Nest E, which I might be returning. I’ve been happy with the Sensi Touch Thermostat. But I heard is better to use a hose. Lesson learned, don’t leave the doors open with the AC on.