So I have an old Nest e thermostat. Since moving into my place more than a year ago there has been an error that I don't have power to my C wire. This has locked me out of controling things from the thermostat itself and using the basic features of the Nest app, honestly very dumb.
I'm able to restart the thermostat and have a minute or two of control at the thermostat but that's not realistic. I was able to setup a schedule through the nest app that keep us from dying but the thermostat was still not charging properly. I ordered a second wiring harness on ebay, cut part of the top out, cut down a micro usb cable, and ran it through the wall behind the thermostat to power it.
This allowed me to power the thermostat but I was still locked out of the nest app. I found that I could adjust the temperature using the amazon alexa app and that worked well enough. Last week there was an update in one of both of that apps that changed the display in the alexa app, I was only able to turn the fan on and off, not adjust the temperature. Interestingly this was something that I'd been unable to do tjrough either app previously so it was fun for 5 minutes until I wanted to adjust the temperature to something lower than my preset schedule.
I ended up ordering an external 24V power source that plugs into the wall for $14 and the nest power adapter for $24. Those arrived today. I installed them using the diagram found on this post.
Link: https://www.googlenestcommunity.com/t5/Nest-Thermostats/How-do-I-add-auxiliary-power-to-Nest-E-therm...
The thermostat was still locked out. So I unplugged the C wire from the wiring harness. This seems to have fixed the issues. The thermostat is powered by the external power source, the app and thermostat both allow me to adjust temepratures.
I'm currently testing out the control and things to make sure they're working as expected, the hvac seemed to being doing 'something' without actually running the fan and pushing cool air anywhere even though it hadn't reached the correct temperature.
