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3rd generation Nest Tstat

Gunfish1
Community Member

My Nest Tstat won't turn on my AC, it blows hot air instead.  I paid a HVAC tech for a service call and he tells me that the tstat is bad (wasn't sending the signal to the cooling unit).  He wired the condenser to work temporarily but says to replace the tstat, otherwise I won't be able to use the heat during the cold season.  How do I get a replacement?

1 ACCEPTED SOLUTION

aatienza
Community Specialist
Community Specialist

Hey Gunfish1,

 

Awesome! Feel free to submit another post, and provide as many details as possible so that others can lend a hand.


Thanks,

Archie

View solution in original post

19 REPLIES 19

Patrick_Caezza
Gold Product Expert
Gold Product Expert

Did it work in the past or is this a recent installation of the Nest thermostat?

If recent, post a picture of the original thermostat's wiring here

Gunfish1
Community Member

It worked fine for the first 4 months, both heating and cooling

Gunfish1
Community Member

Screenshot_20220511-081425_Gallery.jpg

Patrick_Caezza
Gold Product Expert
Gold Product Expert

Sounds like this is the first time that you are using the A/C site since you installed it.

Have you tried changing the reversing valve control? You can give it a try as it won't hurt anything.

If your system starts to blow cool air when your Nest thermostat is in Heat mode (or if it blows warm air when it's in Cool mode), change the settings for orientation of your heat pump.

Nest Learning Thermostat

  1.  On your thermostat, go to Settings.
  2. Select Equipment.
  3. Select Continue > Continue.
  4. Select Heat Pump.
  5. The Nest Thermostat defaults to an O setting for heat pumps. 
    • If the O option is highlighted, select B.
    • If the B option is highlighted, select O.
  6. To make sure the issue is resolved, test your heating and cooling again.

 

I followed your instructions and had the same result.  Hot air still comes out of  the vents on the cool setting.  Anything else I should try?

 

Gunfish1
Community Member

I did test the AC mode when I first installed it and it worked fine, ,although I didn't run it very long.  I'll check out the settings when I get home today.  Thanks very much for the detailed instructions! 👍

Gunfish1
Community Member

It was set to O, so I set it to B.  When that didn't work, I set it back to O again.

Gunfish1
Community Member

I'm still having the same problem.  Is there anyone who can help me?

 

BobbyParadise
Community Member

I am having the same issue, the problem is with the Nest itself. There is an (apparently prevalent) issue that causes the O/B wire to not become energized such that the heat pump reversing valve will not activate. Saw online a tech guessing there’s a bad FET controlling the O/B wire signal. Confirmed at my unit, with the unit set to both heating and cooling mode, and with the orientation both set to O and B. Never voltage on the O/B wire. Jumping the O/B and R together at the compressor turned on the cooling right away. Replaced the Nest with a Honeywell stat and all worked as it should. You (and I) have a faulty product. 

Thanks, Bobby.  Any luck on getting a replacement or is this money down the Google drain?

Hoping to get something. Mines only 5 months old and the cooling didn’t work on the first day I tried to switch over. Started a warranty claim, they were saying I’d have to pay for a new unit and send back my old one, then they’d reimburse. Phone call got cut off before I was finished talking but that doesn’t sound the best to me…

Gunfish1
Community Member

Lovely.  Guess I'll try to call anyway.  Thanks for the input!

Gunfish1
Community Member

Anyone know how I proceed with a warranty claim?

Start at support.google.com. I eventually got to an option for them to call me. 

Hey, Bobby.  I made my way to the chat option.  Long story short, they sent me a replacement tstat and it works!

aatienza
Community Specialist
Community Specialist

Hey folks,

 

As we got our resolution here, I'm going to mark this one as resolved. Please feel free to open up a new thread if you need assistance. 


Thanks,

Archie

👌

aatienza
Community Specialist
Community Specialist

Hey Gunfish1,

 

Awesome! Feel free to submit another post, and provide as many details as possible so that others can lend a hand.


Thanks,

Archie

Gunfish1
Community Member

Thanks again, Bobby