Fan running when furnace is off

[absaroka6]

The fan keeps activating even when the thermostat isn't asking for heat.

Thought it was a problem with the furnace, since the fan schedule is disabled, and there's no fan schedule set up on the thermostat, but when I pull the thermostat off the wall, the fan stops immediately. When I put it back, the fan starts up again, so it's clear the thermostat is activating the fan. But I've checked every setting in the Nest, and no fan schedule is set.

When the thermostat calls for heat, all works fine, but why is the fan running so much when no heat is needed?

Edit: I had such confidence in the Nest thermostat that I waited for a long time before removing it and attaching a Honeywell. The Honeywell operates the furnace correctly, so I now know it was the Nest malfunctioning.

[hbundy]

I found a setting in options on the Nest App on my computer.  it says to run the fan between certain times.  somehow this got set on.  I turned it off and the problem stopped

[skipadin5]

Thanks! This was the issue for me. The Fan schedule was somehow turned on for 60 Minutes every hour and the fan switch would not turn off the fan.

[Radioteeth]

None of this worked for me. Fan constantly runs. I have a C wire. I pulled the G wire (the ac wouldn't turn on). Fan schedules and airwave are both off. It's not the relay. The fan turns off when I pull the unit and when I use any other thermostat. What gives?

[hvaczolt]

C is wired in and I still have the fan running when it is not calling.  I have the E Nest.  I have zone and other two of three are fine. I think sub base is bad, I'm trying to get nest tech support

[Vineet]

It wasnt a wiring issue for me. I had other bad components related to a bad circuit board. When I replaced the board, everything work. 

[Markjosephp]

Hi folks,

@Vineet, thanks for posting and sharing how replacing your HVAC system's circuit board resolved the issue. Please let us know if you have any other questions or concerns.

@hvaczolt and @shenson, I'm sorry for the trouble this may have caused you—let's see what's going on.
 

Make sure that Fan Schedule is off or disabled, then restart your thermostats to refresh. Here's your guide to the settings.

Please let me know if that helps.

Thanks,

Mark

[Markjosephp]

Hi there,

I just wanted to see if you still needed help. Please let us know if you have any other questions or concerns.

Best regards,

Mark

[aatienza]

Hey there,

Just checking in to make sure that you've seen our responses. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.
 

Thanks,

Archie

[Radioteeth]

I've seen reponsnses and nothing works. I've had an HVAC specialist come and he says there's an issue with the nest thermostat. Tested on other thermostats and no problem. I bought a new one and same thing.  Someone from Nest needs to sort this out for me. 

[aatienza]

Hey Radioteeth,

I’m sorry to hear you’re having trouble with this. Could you fill out this form and let us know once you're done?

Thanks,

Archie

[EdwardT]

Hi Radioteeth,

I'm checking back in. Were you able to fill out the form? Let us know if you have questions and we'd be glad to assist you.

Thanks,

Edward

[Skidude]

I too am having same problem. Heat pump turns off when reaches temperature and furnace fan keeps running. I'm going to try another make of thermostat. If it works i'll toss my nest in the garbage. Seems too many people having problem with no resolve

[EdwardT]

Hi Skidude,

Thanks for letting us know. Please fill out the form that Archie provided so we could investigate further.

Thanks,

Edward

[Skidude]

Problem solved. Bought an Ecobee. Issue is gone!

[EdwardT]

Hi Skidude,

Thanks for the update. We're sad to see you go. We hope we can make it up to you in the future. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Thanks,

Edward

[DaveBaumann]

I have the same issue. Ran fine for four years. Now, suddenly, the blower runs continuously and will only stop running if I remove the thermostat from the base. I installed my old thermostat (not a Nest) and all is well.

[JimKov]

I found that my problem was also due to the common ground. Fixed that and it now works again