Nest Learning Thermostat (4th gen) suddenly asking for "R wire" after working fine for 3 months

[jjae0331]

Hi everyone, I'm hoping to get some help with a strange issue I'm having with my Nest Learning Thermostat.

I've had the 4th gen Nest installed for about three months, and it has been working perfectly without any problems. I've been happy with its performance.

However, yesterday, the thermostat suddenly went offline and is now showing an error message on the screen (see attached photo). The message says, "R wire is needed" and "An R wire is needed to supply power to the Nest Learning Thermostat (4th gen). You must connect an R wire to continue setup."

The odd thing is that the thermostat was working fine for three months, so the R wire was clearly connected and providing power. 

So I thought this is C wire issue so I tried to install power connector, but it did not worked. 

Even more confusing is that when I took the Nest off the wall and back to previous one I had before which is a standard thermostat, it works perfectly and controls the heating and cooling without any issues. This suggests that the wiring from the HVAC system to the wall is still intact and functional.

Any advice, suggestions, or similar experiences would be greatly appreciated. Thanks in advance for your help!

[jpicca]

It was running on you battery now its dead you need the c for power 

[EduardoN]

Hi @jjae0331, 

Thank you very much for contacting this community! I understand what you've been experiencing with your Nest Learning Thermostat (4th gen). It worked perfectly for three months, but now it's saying "an R wire is needed." I appreciate that you've taken the time to verify that the R wire is connected to your system, installed the Nest Power Connector, and used your previous thermostat to confirm that everything is working perfectly. Don't worry, I'm here to help you!

To give you the most accurate information, I'd like to ask you a few questions.

• Which wires are installed in your Nest Learning Thermostat (4th gen)?
• What type of furnace do you have? (gas, electric, etc.)
• You mentioned you attached a photo with an error, but I can't see it. Could you please send it one more time?

Please feel free to share any additional details you think might be relevant.

Best regards,
Eduardo

[jjae0331]

My furnace use natural gas and I have R, W1, Y1, G, and C&G jumper wire installed. This C&G jumper wire is kinda weird, because If I use other short wire as jumper it does not work. So I had to use electrical tape to this short jumper wire with the other wire since Nest's C & G is longer than that jumper wire.  So when I did that it worked for 3 months and Nest was not working near early June.

I have attached picture of my previous thermostat's wire setup, because I am currently using the previous one right now. My previous thermostat is still works great, but Nest doesn't. 

Thank you Eudardo in advance

[EduardoN]

Hi @jjae0331,

Thank you very much for all the information provided! Regarding the wiring, I'd like to point out that the jumper you used on your old thermostat between G and C is not needed for the Nest Learning Thermostat (4th gen), as it is designed to work without jumpers. For this reason, I'd like to show you the correct wiring you should use:

• Red - RH
• White - W1 
• Black - Y1 
• Green - G

Keep me posted.

Best regards,
Eduardo

[jjae0331]

I have uninstalled the nest power connector. Should I re install it to try, since your guide does not include c wire? 

[EduardoN]

Hi @jjae0331,

I understand your question about the Nest Power Connector. In this specific case, the Nest Thermostat, Nest Learning Thermostat, and Nest Thermostat E are designed to work without a common wire. For that reason, to ensure the correct installation of this device, I would like to provide you with a video on how to install it: How to Install a Nest Power Connector for Your Nest Thermostat.

Keep me posted.

Best regards,
Eduardo