Fixing Nest Thermostat Fan Won’t Turn Off

November 23, 2022 0 By tech

Not using C wire and fan scheduling settings are 2 common problems that cause Nest thermostat fans won’t turn off. Hardware issues, outdated firmware, and electricity power leaks can cause the fan won’t turn off. You can fix some of that problems yourself or if you are not sure what you are doing you hire a professional.

Software / Configuration Problems

Before checking hardware and wiring problems, check if there are software problems first. Here are tips that may help you fix the fan that won’t turn off.

Turn off the Fan Schedule

Nest allows you to control the fan individually. It means you can set when the fan will run without doing heating or cooling. If you set the fan schedule, the fan will not stop after heating and cooling.

Nest Disable Fan Schedule

You can disable the fan schedule by going to Settings > Fan Schedule. Click on Always and select Disable.

Restart NEST

Restarting Nest will reset any settings, it’s just rebooting the devices like rebooting the computer. To restart Nest goes to Settings > Reset > Restart.

Reset Nest to Factory Settings

Resetting Nest will erase all settings that you have made on your Nest. A factory reset can fix some Nest issues that are caused by misconfiguration.

Resetting Nest to Factory settings:

  1. Go to Settings > Reset > All Settings.
  2. Choose Reset.
  3. Nest will be restarted and you must reconfigure Wifi and reconnect your account.
Factory Reset Nest

After finishing all configurations, test if the fan turns off after cooling or heating.

Update Firmware

Outdated firmware can also cause performance issues on Nest. By updating to the latest version you will get better performance and some issues on the previous version will be fixed on the newest version.

Updating Nest Firmware:

  1. Go to Settings > Software > Update.
  2. Nest will check for the new version and download it if available.

Wiring / Hardware Problems

If you try all solutions above and not resolved your fan problem, you may need to check your Nest wiring.

Install C Wire

Google says Nest did not require C wire, heating or cooling wire is enough to provide power for the Nest thermostat. But it’s better to install C wire because C wire will provide constant power for the thermostat.

To check if your Nest thermostat has C wire, you need to take off your Nest off the wall and see if there there is cable on C socket.

Nest C Wire

if there is no C wire, you need to install it. If you don’t have C wire you use Nest Power Connector or run a new wire.

Here is an explanation of what if you don’t have C wire.

if you want to use Nest Power connection, watch the installation guide below:

By installing C wire your Nest thermostat will get constant power, and hopefully, it will fix the Nest fan and won’t stop the problem.

Disconnect & Reconnect G Wire

G wire is used to control the fan. If your fan has a problem try to disconnect this wire and check if the wire is still good. if everything is ok, you put it back in. Try to turn on and off fan manually to see if the fan working properly.

Electricity Power Leak

An electricity power leak can cause the fan won’t stop because the fan keeps getting electricity even though Nest switched it off. to test this you must have Non-Contact AC Voltage Tester. Check your Nest backplate, if the voltage tester show there is electricity on it, you need to call an electrician to fix it.

Non Contact Ac Voltage Tester
Non-Contact AC Voltage Tester

Broken Hardware

If you do all solutions above and the fan still won’t stop, the problem may be in your Nest thermostat’s hardware. this rarely happens, but Nest thermostat have 2 years warranty, try to contact Google Store or Google-authorized retailer to ask for a replacement.

There are also professional electricians or Heating & Air Conditioning experts that can fix thermostat. You can try to call them if your warranty is expired.


Using a nest will help control the temperature of the house automatically. But sometimes there is a problem that can be caused by various factors. If there problem problems. I suggest you check your thermostat configuration first before checking the wiring. Restarting or Resetting all settings usually fix some issue. If you to check the wiring make sure you have turned off the breaker and use Non-Contact AC Voltage Tester.