I recently bought a Nest Thermostat and I've had nothing but trouble with it. The main symptom is the fan and the AC compressor won't run at the same time. Power only comes through the green wire, not the yellow. So I have been running AC with no fan just to make it through the hot summer days.
I think I have narrowed down my problems to not having a common wire connected. Luckily, I have an 18/5 bundle running to the thermostat so I was able to connect the common wire. However, the nest reported no power to common (E79). I started to look into the HVAC unit manual and I ran across the following sentence.
Do not use any type of power-stealing thermostat. Unit control problems may result.
I know Nest thermostats can be power-stealing. Is this a show stopper for me? Do I need to revert back to a "dumb" thermostat?
- 3rd Gen Nest.
- HVAC Unit Model Number: PY4G 30060 ATP
- Link to the HVAC Install manual. Quote is on page 11, Control Voltage Connections: https://resource.carrierenterprise.com/is/content/Watscocom/payne_py4gnab24060--tp_article_1466843547903_en_ii