Nest Learning Thermostat 4th Gen Does Not Allow me to Turn on my Fan Manually

[rcanlas059]

My original thermostat was a Honeywell T6 Z-Wave smart thermostat. It has a five wire configuration Y, G, W, C, and R. It has the following functions for the fan Auto/On/Circ and I could turn on the fan manually whether the HVAC system is running cool air, hot air, or nothing at all. 

I upgraded to the Nest Learning Thermostat 4th generation. All functions including cold air and hot air work fine with the fan turning on automatically. However, I am unable to run the fan manually even if turning on the fan on a set timer per the instructions. I thought perhaps it was my HVAC system, however, after hours of troubleshooting and using different settings. I'm still unable to run the fan manually. I reinstalled my original smart thermometer and it was able to run the fan manually.

I've attempted to canvas the community forums regarding this issue and I have not been able to find any solution to this problem. It's a shame that a $400 item is unable to perform the same functions as a smart thermometer that's half the price or a dumb thermometer that's an 1/8 of the price. 

[Geezman]

You can schedule the fan to run in the "Schedules" section of the thermostat in the Home app. When you enter the "Schedules" section, there should be a tab button labeled "Fan".  Select that and you should be able to schedule the fan to run.

[rcanlas059]

I've set up a fan schedule to run for 15 minutes every hour with the schedule set up to start at 0:00 and end at 0:00. Is this start and end time correct to run the schedule 24 hours? 

[Geezman]

Yes.  This should have it run for at least 15 minutes an hour, 24 hours a day.

[Geezman]

One other thing, like @humbertogarcia stated below, this will only work if you have your G terminal is connected to a separate fan wire in your forced air system.

[steffinjack4]

Especially since manual fan control is such a basic feature. Oddly enough, I’ve seen others mention the same issue with Nest’s fan timer not triggering the G wire as expected. Seems like a software limitation, not hardware.

[rcanlas059]

Yes, I would agree. I've found other posts regarding this issue (but no solutions) and a member believed that the software is being defaulted to Auto with no clear ways to turn on or circulate the fan. 

[humbertogarcia]

Hi rcanlas059,

Thank you for posting in the community! I'm glad to state, in other words, the steps provided by @Geezman.

If your Nest thermostat's G terminal is connected to a separate fan wire in your forced air system, you can manually run the fan even when heating or cooling isn't active. Otherwise, the fan will only operate automatically during heating or cooling cycles.

To run the fan manually:

On the Nest Thermostat Display:

• Press the thermostat ring to open the Quick View menu.
• Navigate to the fan icon and select it by pressing the ring.
• Choose your desired run time (typically 15, 30, 45, or 60 minutes) by turning the ring.
• Press the ring again to start the fan

Using the Google Home App:

• Open the Google Home app.
• Tap and hold your Nest Learning Thermostat (4th gen).
• Tap Fan.
• Select your desired run time.
• Tap Run fan.

These steps should allow you to control the fan manually. @steffinjack4 Thank you for your feedback.

Please let me know if you have any updates or further clarification.

Regards,

Humberto

[rcanlas059]

Thank you for your reply. I own two Nest Thermostats 4th Generation for a dual zone HVAC system. I've tried to run the fan manually via the  Nest display on both thermostats separately as well as through the app. Both fail to run the fan manually despite waiting 10 minutes to see if this will trigger the G wire to turn on the fan.

To confirm that it's not my HVAC system, I reinstalled my previous smart thermostat and was successful in manually turning on the fan by setting the fan setting to On or Circ while leaving the Heat/Cool mode set to off. 

I've found other posts from Community Members highlighting the same issue with no clear solution. 

[humbertogarcia]

Hi rcanlas059,

Thanks for the update on your Nest thermostat's manual fan control.

The issue might stem from your fan settings. As a quick test, please turn off your thermostat display and then try manually turning on the fan using the Google Home app, following the steps I shared earlier. This will help us isolate whether the app can control the fan directly.

If that doesn't work, the article Fan control with a Nest thermostat provides detailed information on configuring your fan. Specifically, you'll want to check if the fan control is set to operate with your furnace or directly with the thermostat, as explained in the Test your system with a Nest thermostat help article

If more investigation is needed, feel free to attach:

• A picture of your old wiring configuration. This will help me visualize the wire connections.
• If possible, a picture of your control board. It's usually located near the furnace.
• A picture of the current wiring configuration on your Nest Thermostat.
• A picture of the configuration on the Nest or Google Home app.

Take care that your thermostat S/N or any other private information is not included.
I look forward to your answer, Let's work together to fix this situation!

Regards,

Humberto

[rcanlas059]

Thank you for the information. I'll check this out when I'm back from vacation. I don't remember getting the option to set the fan control with the furnace or directly from the thermostat when setting up the Nest Thermostat. I'm eager to factory reset the thermostats and go through the set up process again. Hopefully this will fix my issue. I'll keep you posted. Thank you again for you help.