Nest heating in cool mode

[Macabe77]

Installed Nest Learning thermostat a couple weeks ago. But when on AC mode it blows up heat. I tried changing the settings for orientation of the heat pump, resetting but nothing worked. I took it off and reinstalled the original thermostat.  Installed again and didn’t work. 

 

 

 

[MelbaDT]

Hey Macabe77, 

Sorry for the delay but thanks for the photos. 

Based on the photo of your original thermostat wires, you don't have a heat pump so changing the orientation would not help. Just to confirm, did you wire your Nest thermostat like what your Nest app showed you how to wire it? Could you share a photo of your Nest thermostat wires?

Best, 

Melba

[MelbaDT]

Hey there, 

Checking back in — how's it going? Still need our help with your Nest thermostat?

Best, 

Melba

[MelbaDT]

Hi, 

We haven't heard from you in a while so we'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the Community.

Best, 

Melba

[Macabe77]

Hi,

Apologies for the delay. I installed it in the same way as in the nest suggested picture. Hot air was blowing when in cool mode. The only difference I noted was the R-Rc bridge. I’ll try it again today and upload pictures.

in advance thanks,

[MelbaDT]

Hey there, 

No biggie — you take your time. The jumper wire connecting the R to RC terminal is not needed. 

Best, 

Melba

[Ryan_G]

Hey everyone,

I'd like to jump in here and check if you've seen Melba's response. Let us know if you need more help by replying to this thread.

Thank you for your help, Melba.

Regards,
Ryan 
 

[Ryan_G]

Hey there,

Thanks for being here in the Google Nest Community. 

I'd like to bump in here and make sure that you’ve seen our response.
Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.

Have a great day.

Best regards,
Ryan
 

[Macabe77]

Hi there,

thanks for the replies. I’ll re install tomorrow morning. 
When I installed it the first time, exactly as the best picture suggests, hot air was coming when in cool mode and when in heating mode it was just ventilating air (but not hot). Maybe it’s some software configuration? I’ll try again in the morning,

thanks much! 

[Jake]

Hey Macabe77,

I wanted to check in with you, and see if the re install had worked out for you. Were you able to get the issue resolved? Please let me know, as I would be happy to take a closer look and help you resolve the problem.

Best regards,

Jake

[Macabe77]

Hi Jake and Team, 

Thank you for your reply. 

I’ve reinstalled and I encounter the same problem: when in cool mode, unit blows hot air; when in heat mode, nothing happens (vent off). I reinstalled original thermostat afterwards, works well. Only difference I note is the R-Rc jumper. 

See attached images for reference on wiring. Hope you’re able to help me out, 

In advance thanks! 

Best,

Original Thermostat Wiring

Image 1. Original System Wiring

Nest App Suggested Labeling

Image 2. Nest Suggested labeling

Wires Selected as connected

Image 3. Wiring selection

Nest Wiring Tested

Image 4. Wiring tested

Wiring Detected By Nest

Image 5. Nest Detected Wiring

Additional images

Testing of Cool ModeAppendix: Question on Heating systemResponse

[Jake]

Hey Macabe77,

I am sorry to hear you are still running into the issue. Do you mind me asking, have you tried installing the power wire (Red) to the RC instead of the RH? The RC wire is the power wire for your cooling system. Please let me know if that helps.

Best regards,

Jake

[Jake]

Hey Macabe77,

I wanted to check in and see if you are still in need of any help with your device. Please let me know, as I would be happy to assist, and answer any questions you may have.

Best regards,
Jake

[Ryan_G]

Hey there,

Thanks for being here in the Google Nest Community. 

I'd like to bump in here and make sure that you’ve seen our response.
Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.

Have a great day.

Best regards,
Ryan
 

[Macabe77]

Hi Jake,

Thanks for getting back. I tried the wiring you suggested (see pic), same problem - hot air starts to blow when in cool mode. Any other suggestions or thoughts on what might be causing this issue?

In advance thanks!

 

[Ryan_G]

Hi Macabe77m,

Thanks for being here in the Google Nest Community.

Based on the details from your previous responses, it looks like we're having a power related concern. It is usually happening when the Nest Thermostat is not getting enough power from the HVAC unit. We could get this sorted out by connecting a common (C) wire to the thermostat. 

You could look for an unused wire from the HVAC that we can use to be a C wire.

Regards,

Ryan

[Macabe77]

Thanks Ryan,

There’s an extra, unused yellow wire coming from the HVAC. Should I connect this to C in the thermostat? Is this safe for the hvac? Meaning, can it be wired in some way on the other end that can cause damage to the HVAC unit?

in advance thanks!

[Ryan_G]

Hi Macabe77,

Thanks for the reply.

Before we connect the yellow wire as a C wire, we'll need to verify its connection to the main board. The C wire (terminal) is not controlling the HVAC cooling or heating, it is for the power coming from the HVAC to the thermostat. 

Regards,

Ryan

[Princesss]

Hi there,

We just want to check if you have seen our response posted above. Let us know if you have additional questions, otherwise we'll be locking the thread.
 

Best,

Princess

[Princesss]

Hi there,

Due to inactivity, I'll go ahead and lock this thread in 24 hours. Feel free to start a new thread if you need assistance with your Nest Thermostat and we'd be glad to assist you further.
 

Best,

Princess