Hoping someone can help me here. I'm out of ideas. I’ve had a Nest 3rd gen thermostat for 3 years. Starting this cold season, I noticed that whenever the thermostat would call for heat, quite often the furnace would kick on like normal, run for about 5 min, then it would shut off and start its heating cycle again but this time stay on until it reaches temp. Occasionally it will short cycle a couple times in a row. The thermostat doesn’t put out any errors or anything. It just remains orange and is acting like the nothing happened.
I remember this being and issue when I first installed it. It would constantly short cycle until I finally hooked up a C-Wire and then it worked perfectly until now. I called Nest and they informed me that it appears to be inconsistent voltage to the thermostat. So I replaced filters, the furnace transformer, the fuse, and ran a new wire. I also grabbed a new Nest thermostat and as soon as I hooked it up, the thing just said low battery and didn't seem to want to charge with the C-Wire hooked up. I sent that back since that didn't seem to be the issue. I even just spent $200 on a new control board and replaced that. Not much else I can do and it is STILL short cycling.
While Nest just says it’s the voltage from the furnace, I’ve pretty much run out of things to replace (to my knowledge). Has anyone run into this issue and have you found a resolution? What else could this be?
