Rc / rh wiring issues; Still, nest doesn’t proactively warn you with an email or mobile notification if it detects the thermostat hasn’t registered with the server in. How To Fix A Nest Thermostat That Wont Turn On For instance, there could be warm air that is coming up through walls behind the thermostat. Nest thermostat not working properly . If your nest thermostat is having cooling problems and you are in need of a few troubleshooting methods, try resetting the y1 wire within the nest for any issues with the device not displaying ‘cool mode,’ and reset your external and internal breakers in the case of a power outage. Scroll and tap to open settings restart. Check nest compatibility with your cooling system; If your nest thermostat is not cooling it is most commonly due to one of the following four reasons: Why is my nest thermostat not working? One of the reasons because your thermostat goes offline probably has to do with some technical issues that prevent it from wo...