Nest Thermostat Strange Behavior

[SM11]

My Nest learning thermostat worked well for years but now it often turns off before reaching desired temperature or appears to get "stuck" when asked to increase the temperature to a higher degree number (the little lines that light up between the 2 degree numbers just keep cycling).  If I turn the thermostat off for 1/2 hour or so then turn it back on it will usually connect to the heating unit and the heat will work, at least temporarily.  Also, when it does work it seems to take longer for the heat to kick in.

[Patrick_Caezza]

How do you have it wired?

[Markjosephp]

Hello folks,

I wanted to stop by and see how I could help.

Thanks for lending a hand, @Patrick_Caezza.

@SM11, I'm sorry to hear you're having issues activating your heat using your Nest Thermostat. I'd be happy to take a look at this for you.

To isolate:

• When was the last time you changed the furnace's air filter?
  • Note: A clogged air filter can cause an HVAC system to not activate.
• Have you experienced extremely cold weather lately?
• Are you getting any wiring reports or message codes?
• Do you see a delay timer on your thermostat screen?
• Does it have a C wire or a common wire connected?
• Please collect the power readouts from its Technical information settings.

I'll look forward to your response.

Regards,

Mark

[SM11]

My Nest learning thermostat worked well for years but now it often turns off before reaching desired temperature or appears to get "stuck" when asked to increase the temperature to a higher degree number (the little lines that light up between the 2 degree numbers just keep cycling).  If I turn the thermostat off for 1/2 hour or so then turn it back on it will usually connect to the heating unit and the heat will work, at least temporarily.  Also, when it does work it seems to take longer for the heat to kick in.

[Markjosephp]

Hi SM11,

I've duplicated your thread in the main one here. You’ll receive all updates on this issue on the main thread, and we recommend updating and checking this thread when needed.

Thanks,

Mark

[SM11]

Thank you for these suggestions.  I did change the filter (which didn't help) and confirmed it has a C wire.  I ended up having someone in to look at it and he tried cleaning the heat sensor and it seems to have worked.  It may not have been the thermostat after all.  Thanks for the replies!

[Markjosephp]

Hi SM11,

Thanks for keeping us in the loop on what you've done to have your concern rectified — I'm glad to hear it was sorted out. It looks like we can consider this one complete, so I will lock the thread within 24 hours unless I can help out with anything else.

Regards,

Mark