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Cannot decrease Fan speed - Too high

Mcomfy
Community Member

I have a 2 Stage variable speed furnace. 
The Nest learning thermostat will only operate this furnace on the highest speed which causes air to heat up to fast without heating the rest of the house- floor et. Furnace constant on and off. 
Other than fan speed everything else works as intended. Old thermostat was a Honeywell and worked fine but started to go through batteries at a high rate. 
Fan speed doesn’t even show up on thermostat under setting or in the app. 
CURRENT WIRES: Black, Green, Red & White. All hooked up correctly. 
Anybody have a fix. 

1 REPLY 1

zoeuvre
Community Specialist
Community Specialist

Hi Mcomfy, 

 

Uh-oh! I'm sorry to hear that you're experiencing difficulties with the fan speed control on your Nest Thermostat. Are you located in North America or Europe? And what type of Nest Thermostat do you have? Here are a few suggestions to troubleshoot the issue:

 

  1. Confirm that your specific furnace model is compatible with the Nest Thermostat's fan speed control feature. Some variable speed furnaces may require additional wiring or configuration to enable full functionality with the Nest Thermostat.
  2. Verify that the wiring between the furnace and the Nest Thermostat is correct and properly connected. Ensure that the G-wire (usually green) is connected to the Nest thermostat's G terminal. If the G-wire is not connected, the fan speed control may not be available.
  3. Within the Nest thermostat settings, check that the equipment type and configuration are properly selected. Make sure that the thermostat is set to recognize your furnace as a two-stage variable speed system. This information can typically be found in the thermostat's menu or settings options.
  4. Ensure that your Nest Thermostat has the latest firmware installed. Firmware updates often include bug fixes and feature enhancements. Check for any available updates through the Nest app or the Nest website.

 

I hope that these suggestions help resolve the fan speed control issue with your Nest Thermostat.

 

Best,

Zoe