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Nest is set to cooling but heat kicks on randomly

mds6109
Community Member

Need help pls.  My problem:  Nest is set to cooling but heat kicks on randomly. When this happens (if I'm at home), I flip the power off at the HVAC unit; let system pause for 5-10; turn it back on and A/C returns.  At some point it switches to heat.  There's no pattern to this occurring .... sometimes it's during the day, sometimes it's at night.  A/C will run fine for days and for no reason it switches to heat. 

I have Google Nest Learning Thermostat (3rd Gen).  I have natural gas heat with outside A/C unit; forced air. I have turned off the Auto-schedule, Home/Away Assist, Eco Temps, Safety Temps, Early-On, Cool to Dry, and I'm not running any type of cooling schedule. I've had this problem on/off this spring/summer. 

I've replaced the entire A/C unit (outside unit and coil; it was time.  had nothing to do with this problem) and tried two different Google Nest 3rd generations.  I had this problem with the old A/C unit and original Nest ... and continue to have the same problem with the new A/C unit and 2nd Nest. I've factory reset both Nests but the problem persists. 

I'm reaching the conclusion that the Nest may be mis-wired b/c that's the only variable left in the equation (I believe).  I have a cooling wire (yellow) in Y1; fan wire (green) in G; heat wire (white) in W1; 24V common (blue) in C; and power (red) in RH.

I'm not able to see or respond to replies to this post until after 6pm ET, Appreciate any/all have the Community can provide.  I'll reply/engage in the evening.  Thanks

4 REPLIES 4

luciaaa
Community Specialist
Community Specialist

Hi, @mds6109,

 

Thank you so much for posting in the community. I apologize that your system blows hot air suddenly when it is supposed to blow cool air. I’m happy to assist you and find a solution.

 

To better assist you, please let me know:

 

  • When the thermostat changes the temperature, what temperature does it settle on?
  • Could you share a picture of your control board?
  • Could you share a picture of your thermostat’s wiring configuration?
  • Do you have a Nest Renew subscription, or are you enrolled in the Rush Hour Rewards program?

 

Also, make sure the thermostat wires are completely inserted to the terminals.

 

Feel free to ask any questions you might have along the way.

 

Best regards,

Ana

mds6109
Community Member


[Filter: keyword] mds6109's post body matched "safety", board "Thermostats".


Post Subject: Nest is set to cooling but heat kicks on randomly


Post Body:


Need help pls.  My problem:  Nest is set to cooling but heat kicks on randomly. When this happens (if I'm at home), I flip the power off at the HVAC unit; let system pause for 5-10; turn it back on and A/C returns.  At some point it switches to heat.  There's no pattern to this occurring .... sometimes it's during the day, sometimes it's at night.  A/C will run fine for days and for no reason it switches to heat. 


I have Google Nest Learning Thermostat (3rd Gen).  I have natural gas heat with outside A/C unit; forced air. I have turned off the Auto-schedule, Home/Away Assist, Eco Temps, Safety Temps, Early-On, Cool to Dry, and I'm not running any type of cooling schedule. I've had this problem on/off this spring/summer. 


I've replaced the entire A/C unit (outside unit and coil; it was time.  had nothing to do with this problem) and tried two different Google Nest 3rd generations.  I had this problem with the old A/C unit and original Nest ... and continue to have the same problem with the new A/C unit and 2nd Nest. I've factory reset both Nests but the problem persists. 


I'm reaching the conclusion that the Nest may be mis-wired b/c that's the only variable left in the equation (I believe).  I have a cooling wire (yellow) in Y1; fan wire (green) in G; heat wire (white) in W1; 24V common (blue) in C; and power (red) in RH.


I'm not able to see or respond to replies to this post until after 6pm ET, Appreciate any/all have the Community can provide.  I'll reply/engage in the evening.  Thanks


Body text "Safety" matched filter pattern "safety".


Post by User[id=575228,login=mds6109] has message uid 632802.


Link to post: Nest is set to cooling but heat kicks on randomly

mds6109
Community Member

Thx, Ana — appreciate any all help you can provide. I’m on vacation and away from house til early August. Pls keep this thread open while I’m away

PS I turned the nest thermostat off completely before I left for vacation

 

luciaaa
Community Specialist
Community Specialist

Hi, @mds6109

Thank you very much for your response. Please feel free to respond when you return home. I’m happy to assist you further. Enjoy your vacation!


Best regards,
Ana