I know, It's quite a Subject line but feels to be true! I installed two Nest Gen 3 Learning Thermostats about two months ago. They've been working perfectly from day one. We were on a road trip and I was able to monitor them from the app. We also had a house remodel going on and last week the painters unplugged our router too paint our office. After plugging back in the guys where mentioning one side of the house was hot and getting hotter. The 100 degree Arizona weather was creeping in along with a Gremlin or two. I was unable to reconnect to the thermostats remotely until I was on site. I walked in the house and noticed one side was cool while the other side was 88 degrees. Our guest bathroom was a sauna and our toilet was HOT! 🥵 LOL! The nest thermostat on the hot side was set to cool to 72 degrees but was blowing hot. So here's what I've found:
The thermostat had not been touched. I exchanged thermostats and it acted the same on the hot side. I exchanged the Nest at Home Depot for a new one to rule out a bad wall mount circuit board, set up the new Nest and keep getting the same results. Our HVAC guy checked the system, wiring, Nest set up including O/B selection and said everything is fine and doesn't understand this pattern. Here's what it will do: If I unplug the Nest from the wall, plug back in, set to cool it will cool! When it reaches a comfortable temp it will shut off like normal. The next time it kicks in it starts blowing hot air inside with the condenser blowing cool outside. If I turn it to heat it will heat and then turning back to cool will cool until it shuts off. Then it's back to blowing heat in cool mode. Gremlin.
The AC guy installed a spare, typically uncool thermostat and guess what? The system runs perfectly. No hot toilets. The pattern is predictable so I'm at a loss. I love the Nest thermostat and hope someone else know's a solution to fix this. I also hope posting this won't trigger the government, scientists and researchers to come over, quarantine our the fam and cover our house in plastic while they scan the place with ghost hunting devices at 3AM.
If nobody can help I'll go back to the old thermostat and head out back to churn some butter.
