Nest Thermostat won't go into defrost mode

[Esmith]

My nest thermostat will not go into defrost mode. At night if the outside temp falls below 40° my outdoor unit will get a layer of ice and cold air will blow inside the house. I had someone look at it and they told me it's the thermostat not sending the signal to defrost. What do I do? I have 6 wires Y, C, G, O/B, R, and W2.

[listairee]

Hello @Esmith,

Thanks for reaching out. A couple question to help you troubleshoot further:-

1. When did you have your Nest thermostat installed? 
2. Was everything working well before you installed the Nest thermostat? 

If everything was working before you installed the Nest thermostat, it is very likely that you did not installed it correctly and you'll have to recheck your installation. I've included a step-by-step guide to help with that.

Hope that helps! 🙂

[Esmith]

We just purchased the house at the end of December and it was already here from the previous owner. 

[Esmith]

Also there is a brown wire and a black wire that are not being used. 

[listairee]

Hello @Esmith,

You will need to redo the installation to ensure everything is installed correctly. If you are not familiar with doing the installation yourself, it is best to reach out to a local Nest pro to help out with the installation. They will be able to rectify this issue.

Hope that helps! 🙂

[Esmith]

Still not defrosting.

[Jenelyn_O]

Hi there,

Thanks for reaching out. I'm sorry for the delay. I just want to confirm if you were able to try the recommendation of listairee. Also, do you see any messages or code on your thermostat screen? 

I appreciate your help, @listairee.

Best,
Jenelyn

[Esmith]

A little too late now. I guess customers aren't of value to you guys. None of that worked and no one reached out so I replaced it with a GE Cync thermostat and haven't had any problems since. 

[Jenelyn_O]

Hi Esmith,

We deeply appreciate you sharing your thoughts and experiences with us — we're sad to see you go. We hope we can make it up to you in the future. We're always here to help if you ever change your mind. We'll leave this topic open for another 24 hours in case there are any follow up questions or comments. Please let me know if you need further assistance.

Regards,
Jenelyn