6.2.27 Firmware issues

[drtelford]

I started notice early this morning around 7:30 AM CST my 3rd Gen Nest thermostat seemed to have problem turning the A/C unit on for the first floor of my home. I also noticed that the battery seemed to getting weak.

What I did: 1) removed the display unit 2) recharged it manually for 3 hours, 3) plug the display back to the base, 4) Set the thermostat to Cool mode, 5) the AC unit came up but kept recycling, 6)went up to my home's attic to check on the equipment. Everything was fine. No water found on the tray below the unit. 7) went back downstair to the thermostat, 😎 put the unit in OFF mode - but the AC kept recycling, 9) went to the main electrical panel in the back of the house and put the switches, which controls the electrical current to the thermostat, to the off position, 9) found that the AC is still running, 10) removed the display from the base of the thermostat, 11) AC unit finally stopped running.

It looked like it's a firmware issue. the issue category does not have any firmware  category. So, I have to put it in the wiring and system compatibility category.

I wanted to know if anyone else experiencing this problem. Thank you.

[drtelford]

I noticed the above issue today, Oct. 19, 2024 around 7:30 AM CST.

[AxelD]

Hi drtelford,

Thanks for posting in the Community! Sorry to hear that your A/C is constantly cycling and continues running even when you set it to off. I appreciate the troubleshooting done. No worries, help is here! Please provide me with the following information:

1. What type of system do you have? (Heat Pump or conventional type)
2. Could you post a photo of your previous and current wiring?
3. Can I get the power readouts of your Nest Thermostat?
    

Keep me posted.

Regards,
 

Axel. 

[drtelford]

Alex, thanks for your response. Following are my answers:

System is traditional.

Wiring is the same - Previous and present.

Power was weak when I first noticed that the A/C was struggling to get on. Probably it had been doing that most of the evening. The attached phot shows what the batter power was a few minutes ago because I had to recharge it manually yesterday.battert powerwiring

[AxelD]

Hi drtelford,

Thanks for providing that information; it’s really helpful! Checking the power readouts, I noticed that the VIN is lower than the expected one. The recommended readings for a Nest Learning Thermostat without a C-WIRE are:

• Battery: 3.6V
• Voc: 29 to 42V
• Vin: 29 to 42V
• lin: 20 to 40 mA
   

Your system may have discharged because it’s not getting enough power to stay on. I recommend installing a C-WIRE or Nest Power Connector to provide your thermostat with a constant power supply.

Let me know if you have any questions.

Regards,
 

Axel.