Dehumidifier wiring

[js8045]

I have a 4th gen Nest that I installed a couple of months ago. At the time, I had a wire marked "D" for dehumidifier that I attached to the * connector and chose dehumidifier for the * option.

Sometime this week, I got an error that my wiring had changed. I no longer have a dehumidifier option for *, only humidifier and emergency heat. Customer support says to just select humidifier. Given that is the wrong equipment and the exact opposite effect desired I hesitate to do that. Anyone else having this sudden issue?

[moralesvicente]

Hi @js8045, 

Thank you so much for posting in this community. I understand that you have installed a dehumidifier attached to the star terminal (*) in your Nest Learning Thermostat (4th gen), however recently you have experienced troubles with this wiring configuration, and you no longer have a dehumidifier option, just humidifier and emergency heat. No worries; I’m here to help.

In this case to use the humidifier or dehumidifier option with the Nest Learning Thermostat (4th gen) you must connect the cable star (*) to the AQ+ terminal. This is to power and supply to the dehumidifier system when the thermostat bridges the R and AQ+ terminals, effectively completing the circuit. To learn more about how this configuration works, refer to the article on Nest thermostat compatibility.

​Let me know how it goes,

Regards,

Daniel