The wind speed cannot be changed in heating mode

[songzh]

Hi 

I connected Rc C Y1(cool) W1(heat) Y2(fan2) G(fan) *(fan3)

After my test, I found that when I set the automatic fan speed, the fan speed will change with the temperature difference in the cooling state, but not in the heating state. In the heating state, the wind speed will always be kept low.

[CoolingWizard]

The furnace control board is what controls the fan speed.  When you call for heat, the controller starts the heating cycle and runs the blower a lower speed than for say AC Cooling.  This creates a more efficient heating cycle that allows the air to move more slowly over the heat exchanger.  When your gas furnace has a 2-stages heating system, the furnace control board will change the speed of the fan to faster speed when the second stage gas flow is activated. 

Y2 is cooling stage 2 and the compressor changes the refrigerant flow, and the blower fan speed changes.  

 Normally, the AC fan speed is set at High, and if you live in a high humidity area, slower to remove the moister from the conditioned air.  

I hope this helps to answer your question.  

The AC Cooling Wizard

[Jenelyn_O]

Hi there,

Thanks for reaching out @songzh. I hope you've got the answer you're looking for.

You can check this article as well for additional information about Fan control with a Nest Thermostat. 

If you're still in need of any assistance, feel free to let us know.

Thanks for helping here @CoolingWizard 

Best,

Jenelyn

[songzh]

Hi

I can't open the link

can you send it to me use email

[Jeran]

Hey there songzh,

No problem at all, here is the exact link that Jenelyn provided:

https://goo.gle/3pt6vOd

Feel free to manually type it if that is what you need to do.

Best regards,

Jeran

[Jenelyn_O]

Hi songzh,

I wanted to follow up and see if you still need help. Please let me know if you are still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Thanks @Jeran for your help.

Best,

Jenelyn

[Jenelyn_O]

Hi songzh,

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this thread in 24 hours.

Regards,

Jenelyn