Yup, right there with you. My Google Nest 3rd Gen Thermostat decided on its own to set my system to blow only HOT air when I needed the A/C. Performed a reset multiple times and the troubleshooting steps with Google support. My thermostat was just out of warranty. Can you believe the solution given was to buy a new one! I requested a Google store credit for the defective one. That was denied. So, my solution was to switch to an Ecobee Premium thermostat. Clearly, my issue was a factory defect as others have had the same problem. Google simply will not stand behind their product. Worse, they do not seem to care about retaining customers. When asked, I do not recommend Google thermostats.
Oh, when I reinstalled the original Honeywell thermostat everything works fine. The new Ecobee thermostat works fine. Too easy for Google to blame wiring, installation or operator instead of their crappy product.
