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heat and ac run at same time when heating

Community Member

we have 6 wires and I can see both the connections to the next and the connections to the equipment and I can get everything to work except when we call for heat the system runs both the AC and the heat


Community Specialist
Community Specialist

Hello sandiegoscott,


Thank you for taking the time in letting us know about your inquiry. Let's see what's going on.


To isolate:


  • Which type of Nest thermostat do you have? Here's your reference.
  • When did you install it? 
  • Are you getting any wire reports or message codes when your AC activates unexpectedly at the same time as your heat?
  • Could you please tell us the terminals your thermostat is connected to?
  • What's the make and model of your HVAC system?


Looking forward for your response.




Community Member

1st generation

neat w goes to w2

Neat c goes to comm 24v

Nest y goes to y

Nest g goes to g

Nest r goes to r

Nest ob goes to w1

no heat pump only heat and ac on a newer carrier we get no error codes and ac works but no heat

Hi there,


I'm sorry for the late response, and thanks for the details.


Do you mind if you could send us a picture of your previous and current thermostat wiring setup to ensure the correct configuration? Also, going over these steps might help:


  1. Examine the history of energy use.
  2. Disable the Home/Away Assist from your thermostat settings.
  3. Turn off the auto-learning schedule under Nest Sense.
  4. Turn off the HVAC system and remove the Y1 wire, leaving it disconnected.
  5. Put the display back at the base and turn on the HVAC systems' power at the breaker.
  6. Try activating the heat and see if your AC will turn on again.
    1. If so, it's most likely an HVAC issue, and you should contact an HVAC technician.


Please let me know if that helps, or if the issue still persists.


Best regards,


Hi folks,

Chiming in to see if you still need assistance with this. Let us know if you have additional questions ― we'd love to help.


Hi everyone,

Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know.