topic Re: Nest thermostat no heat in Nest Thermostats

Nest thermostat no heat

dothandude — Mon, 11 Dec 2023 15:57:16 GMT

Replaced a Honeywell 5000 with a Nest thermostat and I am not getting hot air.

I have the O wire selected in the app for the heat pump and it is a forced air all electric, Ac/Heat.

The 6 wires from the Honeywell are connected to the Nest as follows:

Yellow: Heat/Cool

Green: Fan

Blue: Common

Red: power

White: Aux. Heat

Orange: Heat Pump

Re: Nest thermostat no heat

Markjosephp — Wed, 13 Dec 2023 21:30:15 GMT

Hello dothandude,

Thanks for reaching out. It looks like your wiring connections are generally correct, but let's troubleshoot the issue. Make sure the O/B wire setting in the Nest app is configured correctly. For heat pumps, it's crucial to determine whether your system uses an O or a B wire for reversing valve control.

Confirm that the O wire is indeed selected for the heat pump in the app. If you're unsure whether your system uses O or B, open the Google Home app, select your thermostat, and then go to Settings > Thermostat > Heat Pump. It should show which wire configuration is currently selected.
- If the O option is highlighted, select B.
Ensure that all wires are securely connected to their corresponding terminals on the Nest Thermostat. Any loose connections could lead to malfunctions.
Restart your thermostat by going to its settings, pulling the thermostat display off its base, and removing the batteries for at least 2 minutes before plugging them back in.
Try power cycling your HVAC system by turning it off at the breaker for a few minutes and then turning it back on. This can sometimes reset the system and resolve communication issues.

If the problem persists, share with us a photo of your old thermostat and Nest Thermostat's wiring set up so we can see how it was being labeled.

Regards,
Mark

Re: Nest thermostat no heat

dothandude — Thu, 14 Dec 2023 13:23:46 GMT

Thank you for your reply.

I was able to get it going. My heat pump is an American Standard that requires the O terminal to energize the reversing valve for cooling not heating. I cleaned and reinserted all of the wires but the Aux wire was not detected by Nest until I restarted. I did not have your reply in time so my restart did not include removing the batteries. All is well now.

Re: Nest thermostat no heat

Markjosephp — Thu, 14 Dec 2023 18:45:41 GMT

Hi dothandude,

Awesome! Thanks for posting and for keeping us in the loop on what you've done to have your concern rectified—give yourself a pat on the back for a job well done!

For any future questions or concerns, feel free to create a new thread. We're always here to help!

Warm regards,
Mark