topic Re: Please help me fix my new replacement Nest learning thermostat 3 in Nest Thermostats

Please help me fix my new replacement Nest learning thermostat 3

MrBeEmW — Wed, 18 Feb 2026 14:38:35 GMT

Hi, please can someone help me with my Google nest learning 3. I had one initially wired with the heat link using T1 and T2 but the thermostat stopped working. Now I have received a replacement . I have installed the new heat link and thermostat. The heating is blinking blue but the thermostat is not working. It switches and then says restarting back in a bit and doesn’t come on. And when it is on it says low power and H72 error. Sometimes it doesn’t even turn on. This is the new replacement from Google. It is being powered using the T1 and T2 terminals. I’m hoping someone can help me. Appreciate all support. Any questions please ask. Thanks

Re: Please help me fix my new replacement Nest learning thermostat 3

Frustratedddd — Fri, 20 Feb 2026 00:37:01 GMT

I would just go back to Google and say, replace this one as it's faulty. You have a reference number from the replacement, just quote that.

Re: Please help me fix my new replacement Nest learning thermostat 3

Derickf — Mon, 23 Feb 2026 01:22:51 GMT

Hi @MrBeEmW,

Thank you for posting in the community. I’m sorry to hear your replacement Nest Learning Thermostat (3rd gen) is experiencing power issues, and it is showing you an H72 error and constant restarting. I understand how important it is for you to have your device working properly. I appreciate the relevant information you shared.

@Frustratedddd, Thanks for jumping in.

To gather the necessary information, please answer the following questions:

Since the device is restarting, please charge the display via a micro-USB cable for 60 minutes first. Once it's stable, could you confirm the power readings in Settings > Technical Info > Power (Battery, VOC, VIN, and IIN)?
Can you confirm if the wires in the T1 and T2 terminals are properly stripped and pushed all the way in?
Apart from the breakers and checking the seating of the display, have you tried any other steps to resolve this?

I'll be waiting for your reply.

Best regards,

Derick.

Re: Please help me fix my new replacement Nest learning thermostat 3

MrBeEmW — Fri, 27 Feb 2026 05:38:22 GMT

I believe the T1 T2 on my heat link are faulty as the screws just keep spinning and do not tighten and as a result the nest thermostat works intermittently. I have spoken with customer support who have sent me a replacement heat link in the post. Hopefully this fixes the problem.

Re: Please help me fix my new replacement Nest learning thermostat 3

Derickf — Sat, 28 Feb 2026 05:02:01 GMT

Hi there!

Thanks for your reply. I appreciate the update and the confirmation that you have already contacted support. Since the screws cannot tighten, it prevents a stable electrical contact, which explains why the thermostat was working intermittently. It is great that they have already sent you a replacement.

Please don't hesitate to keep posting if you have any other issues.

Best regards,

Derick.