I have a problem similar to locked post by @carlygirl . Around 9:45 pm, it jumps to 17C (about 63F), much lower than any of the programmed schedule temperatures, which are 25.5 to 28.5 C.
My A/C runs on a schedule that I created using the schedule tool, with different cooling thermostat settings at 4 different times of the day. Normally, I do not leave it running at all times - I use natural outdoor ambient cooling overnight and in the morning (that is, the windows are open to get cooler outside air, and the mode is set to OFF). In the afternoon, when the outside temperature is higher than the inside, I will then close windows and start the AC (set the mode to Cooling). By 8 pm, I often turn it off again - but recently it has been hotter, so I keep it running until later. And if I leave it in Cooling mode past 9:45, even if the AC has not been called (it is lower than the set temperature), then I get this phantom / ghost temperature of 17 being set on my Nest, and the AC comes on. The cooling schedule has 27C at 8pm and 28.5C at 10pm.
It is not an Eco issue - the Eco temp is also 28.5C.
It might be a fault in the Nest app - there is a 17C in the Heating schedule at 9:30 pm, to let the house begin to cool down in the winter before bedtime.
While waiting for potential response, I plan to delete the whole Cooling schedule and recreate it from a blank slate.
Has anyone else encountered this issue? How did you resolve it?
That is a fascinating theory that I would never have thought of -- that the Nest might confuse your heating and cooling schedules. (From your detailed description it sounds like you're already doing everything right; I couldn't tell from the post by @carlygirl .)
I hope somebody can answer you. In the meantime, maybe you could completely delete the Heating schedule. Then there would be no 17C for the Nest to mistakenly aim at. If your theory is correct, that should change the Nest's behavior.
Sorry about the confusion you've had with your cooling schedule. That sounds quite confusing and frustrating to deal with. It looks like you were going to do some troubleshooting on your end with schedules. I wanted to check in and see if you had tried changing those schedules and to see if it had any impact on your situation. If you're still seeing the issue, I will be happy to jump in and help.
Updates to my Nest “Ghost” 17C change to cooling around 9:30 pm …
1. I did clear the entire Cooling schedule and made it up again from scratch.
2. I have only been running in Cooling and Off modes.
3. The phantom 17C temperature is still getting set around 9:30 to 10 pm or so.
4. I have now reset Heating as follows:
a) Deleted entire schedule.
b) Set Heating value to 15C.
c) Turned off heating and put mode back to Cooling only.
I will continue to monitor the Cooling around 9:30 to 10:30 for the next few nights … Perhaps the removal of the Heating schedule will resolve the ghost setting.
Thanks for keeping us posted and for trying those steps. We're hopeful that this will take care of everything.
We'll keep the thread open for a few days while waiting for your update.
Bad news … Situation not resolved.
I deleted the entire heating schedule. There are NO entries in the heating schedule. I set the heat to 15C. Then I returned to Cooling mode.
It was cooler yesterday, so the ambient temperature never reached the scheduled temperatures for cooling. But shortly after 10 pm, I heard the AC start up. I went to the thermostat, and the ghost had returned and set the cooling temperature to 17C.
Just to be clear, the temperature setting in the schedule was 27C at 9:30 and 28.5C at 10:30 pm. When I checked around 9:30 the thermostat was set to 27 and the ambient reading was 22.5C.
Then after I heard the AC unit power up, I look at the thermostat again, and it is calling for 17C cooling (ambient still 22.5C).
So, I cranked up temperature to 28.5 then turned system OFF.
Any thoughts before I contact Nest support for warranty service?
So, I have deleted the entire heating schedule. Still getting ghost cooling temperature set at 17 around 9:30 - 10:00 at night. (See details already posted in this thread).
And now I have had a new ghost temperature of 21C set at 7am this morning.
Should I be calling Nest for customer service / warranty repair or replacement?
I apologize about the late response on this thread, are you still running into these phantom temperatures? If so, if you haven't already, I would suggest you first restart the Nest Thermostat. If that doesn't help, then go ahead and factory reset it.
I look forward to your response, and if you had any other questions or concerns, please let us know.
My previous steps of deleting and recreating the Cooling schedule did not work.
Last week, I turned off Eco Home/Away functions. I then deleted EVERYTHING in the Cooling Schedule. Then, I deleted EVERYTHING in the Heating Schedule. And all Learning stuff is still OFF.
I am now away for another 2-1/2 weeks. By then, it will be occasional heating and no cooling in our area. I will restart the system, following your recommendation. Then, I will set up a simple Heating schedule and monitor for a while. If that doesn’t work I will do a factory reset … or just reinstall my old programmable, dumb thermostat.
Shoot, no problem at all. Did you want me to leave this thread open for a while to give you time to report back with your findings? If we do end up locking the thread, please feel free to create a new one if you're still having issues.