Gen 4 thermostat N423 code

[Dfore4]

I keep getting an N423 code when the outside temp drops below 10 degrees.  I have an air exchanger hooked up through the AQ+ and AQ- wiring ports.  The N423 url and QR code for the error don’t even work.  From what I can tell for the thermostat is that it thinks there is an overcurrent or Over-voltage.  However when testing the systems power there is no issue with the air exchanger, but with the thermostat itself.  While Google says it compatible with the Air Exchanger I would not recommend hooking up accessories to it, as there is clearly some software and/or hardware issues with the design of this thermostat.  I recommend using a different brand.  This is unfortunate because I do enjoy having a “whole house system”.  If anyone knows of a fix, besides resetting the thermostat every time, please let me know.

[GabrielaG]

Hi @Dfore4,

Thanks for reaching out to the Community. I’m sorry to hear that your Nest Thermostat is displaying the N423 error code and that the QR code for more information isn't working. I appreciate you checking the system's power, and I'm glad to share more information.

I understand that you connected the AQ+ and AQ- wires at your air exchanger, assuming the Nest Learning Thermostat (4th Gen) is compatible. While the Nest Thermostat does feature AQ+ and AQ- terminals to offer flexibility for humidifiers, dehumidifiers, or ventilation systems, these setups often require advanced configuration and wiring. If you have one of these systems, we recommend contacting a professional.

Feel free to keep posting if you have more questions.

Regards,

Gabriela