Nest thermostat cannot turn off fan

[Krazrunner]

My nest seems to be unable to turn the fan off. After running the AC last night, the fan did not turn off all night despite showing that the AC was only used for a total of 12 minutes. I know that the nest uses airwave technology but that would not cause the fan to run all night. Another common cause I’ve seen is that fan is set up to always on or some other schedule within the app. I’ve double checked all the settings and that is not the cause.

To test I’ve set the fan to run for 15 minutes from my phone within the google home app and the nest can turn on but when the 15 minute timer is up the fan does not shut off and the app does not show the fan to be running. All attempts to turn the fan off after that are unsuccessful. I tried manually setting the thermostat to turn on and off the fan again but the fan continues to run. The only way to turn the fan off is to turn off the breaker to the fan and unplug the nest from the hooks for 5 seconds. The same thing happens if I set a 15 minute timer from the nest itself, it will not shut off. 

Has anyone else encountered this situation where the nest is able to turn on the fan but cannot turn the fan off? Any workarounds or suggestions?

[Kenadian]

Just exchanged the thermostat for a new one, and CHANGED the back plate (where the wires connect too) solved the problem. My guess is that if you accidentally busted the fuse or had any arc during the install it may have broken the thermostat backplate. Now my fan turns on and off and doesn't run constantly.  Also, you only need the Google power connector if you do not have a C wire so don't waste your money like I did thinking that would solve the problem.

[TDB1]

What did you do?

[Stigger357]

I did nothing other than post on here, dont know why it is like this, runs some days non-stop and others cycles like it should.

[peacechild]

As mentioned before, my Nest wouldn't turn the fan off. I found the relay was not being energized because of lack of signal. What has happened since then, yesterday, I removed the fan relay and and returned to it's place. It appears that because of me not using the system for a few months the relay was sticking. This is still the same situation, just that the relay is old, and needs to be exercised to function normally.  A new electronic style relay, or upping the signal strength may be the final solution for this fan problem. So, that is the only problem with my system, the relay sticking. 

[madmaxz]

I’m having the same issue. I just bought and installed Nest Learning Thermostat today. The fan will not shut off after running the AC. The only way to turn the fan off is to unplug the display from the wall and the fan will turn off. I’d have to wait for 1 minute to plug it in back to the wall, otherwise the fan would resume running. Any ideas how to fix it?

[madmaxz]

PROBLEM FIXED! I hired an HVAC technician and turns out that the orange wire is suppose to be connect to the G tab. The orange wire controls the fan. Works perfectly now!

[medina80]

I also removed the wire going to the G tab. The fan still continued running and neither the cooling or heating function was runnins. I have a Goodman unit and searching found that AC units after 2019 use new fan motors called ECM motors. Their speed is electronically controlled and a lot more efficient. I call my AC repairman and explained the problem. He said it might be a relay sticking (which is what I thought after removing the G wire in the thermostat) or the ECM motor. He ordered a new motor and will install next week. My Goodman is only 2.5 years old.

[Frustrateduser2]

This system is a piece of **bleep**….switching to Eco

[Spacystacy]

Installed ours yesterday. Doing the same thing. Fan will not turn off. What do we do now? I don’t want to waste time and money on HVAC if that’s not the issue here. 

[Stigger357]

Mine did this as well, i played with all the settings and now it works without any issues and i am running with the eco off and the leaf on. Maybe it just needs to learn the house at least that is what i believe happened. Mine is working just fine now. But i wish it would do monthly reminders to replace the filter and not just when it sees something wrong and tells you. I now have a reminder in my calendar to change the filter monthly.

[medina80]

I had the same problem and I was sure the cause was the Nest thermostat. Many weeks of trying different things I unplugged the fan wire on the thermostat. Fan still continued running. I have a Goodman air handler and it is 2.5 years old. I found a site that has a troubleshooting manual in PDF format and it gives some hints. I turned the circuit breaker off. Opened the cover to the air handler. There is a fan motor relay and it is incapsulated so I couldn't just push it on to see if the fan would run. The troubleshooting chart told me to jumper 2 connections and if the fan runs then isn't the motor. (My A/C man said it could be the motor or relay) When repairman showed up I had everything ready for him and he replaced the fan relay. I Googled the fan relay P/N and found some comments about it not being a reliable relay. It has been over a week now and the fan is working fine so to me it must have been the fan relay and had nothing to do with the Nest thermostat.

[peacechild]

I had the same problem the fan staying on, new install, and the Nest couldn't turn it off. This was a problem with the setting in the Nest thermostat. The "Active", "Don't Activate" in the fan settings, under the "Heat Configuration" was the problem. I had it set to "Activate". Once I switched it to "Don't Activate" it turned the fan off after the furnace cooled down. Hopefully this is the long term fix. I thought it could have been the fan relay but after pulling the relay, and checking it with a multimeter, it seemed to be fine. It may be sticking but only time will tell.

[peacechild]

I had the same problem the fan staying on, new install, and the Nest couldn't turn it off. This was a problem with the setting in the Nest thermostat. The "Active", "Don't Activate" in the fan settings, under the "Heat Configuration" was the problem. I had it set to "Activate". Once I switched it to "Don't Activate" it turned the fan off after the furnace cooled down. Hopefully this is the long term fix. I thought it could have been the fan relay but after pulling the relay, and checking it with a multimeter, it seemed to be fine. It may be sticking but only time will tell.

[Nillyfresh]

I am having this same issue. Have had my Nest learning thermostat for probably two years and never had a problem. Now the fan won't turn off. I shut off the breakers and disconnected thermostat from the wall. When I turn everything back on, the fan starts up immediately, can't get it off. No wiring changes have been done. Infuriating.

[Nillyfresh]

UPDATE: Apparently there is a manual setting on your HVAC blower unit where it keeps the fan running constantly. On mine it is a white button. When I had some work being done on mine, the guys must have accidentally bumped it. I had them back out and they showed me the problem. Now my Nest can shut off the fan. I would check this if you are having the same problem, it could be that.

[peacechild]

The issue I had was resolved with the setting change within the phone app. as I mentioned in the previous post So far, as of 2/6/2023 it is still working as it should. The way mine was with the old thermostat I could switch the fan on but had to turn the AC on to turn the fan off. All that messing around has also been resolved.  

[bskizzotw]

Same issue and this worked for me.  Turn "hold" off.  In the app go to settings for the thermostat > Schedule > fan and set an everyday schedule for a time that is not annoying.  I chose midnight to 1am.  Choose 15 minutes.  After that the fan will only run when the unit needs it and during the 15 minutes scheduled.  Having hold off allows to set temp as you see fit.   

[Spotlite4j]

Same issue after all this year.

google customer service tried to help me with this issue, everything seems right but couldn’t solve the problem so recommended me to replace the nest.  Installed the new one, still same.

AC/Fan wouldn’t turn off after nest is off.

I have found a workaround.

when you turn off the cool, turn on the heat and turn it off right away, in few seconds AC/Fan (system) will shuts off.

Weird but it works.

[Spotlite4j]

Update:

Changing “HeatPump” Active setting, 

from “ Seasonally” to “Each Cycle”

seemed to work as well. 
Setting>> Thermostat>> Heat Pump

(For Nest Thermostat)

[Mes11mini]

I’ve had a nest gen 2 for 9 years and no problem until two weeks ago. Got an email from nest saying it stopped cooling during the night. When I check the thermostat, it said it was nearly 90 degrees but it really wasn’t. Called an hvac tech and he swapped the white wire from W1 to W2. Got another email today saying it stopped cooling. Now the fan won’t turn off with the white wire in W1 or W2. Nest support was no help. Pulling out the white wire was the only way to stop the fan other than turning off the breaker. I installed an old dumb thermostat and it works fine. My theory is the the terminals are defective. Ordering a new thermostat. 

[feeno]

I have the same issue. Just started this week after it disconnected from the wifi and reconnected.

[medina80]

I had a problem with the air handler fan running constantly. After many months of trial and error it turned out to be a defective solid state relay in the air handler that turns the fan on and off. I have a Goodman unit about 3 years old.

[alexo1]

I had nest 2 for years same spot all worked fine replaced with Learning as we needed the ad-on like temp sensors. Now when i try to cycle fan it shows as running but does not start. after reading here i am of opinion its a bug in program causing this. So my question is when are they going to fix it. 

[Ian-G5]

Did anyone come up with a solution for this? 

I see this has been an ongoing issue with nests and they should be held liable for any damages/costs due to their product. I can’t even seem to find a number for someone to help me at google.

[madmaxz]

From what I've been reading, there has been many different solutions to this. Depending on your circumstance. Mine was that the wiring (which I installed) was incorrect. The HVAC tech was called, found that problem, and it was a quick fix for me. Hope you get your issue fixed!

[peacechild]

My Nest started to run the fan again constantly. The fix I first used, earlier posts, failed to do anything. If I open the furnace cover and tap the fan relay, the fan stops. This was happening when I first installed the Nest, as well. It could just be that we haven't run the unit for a few months and the relay is sticking, but does that mean the relay is the wrong one to control the fan with the AC and the Nest. Or, the Nest needs to send a stronger signal? Is it a power supply to the Nest problem?

I did some further reading and found that if a furnace is old, it may not have been installed with AC, then AC was added later. The fan relay was not designed to work with the AC, although it can. I read that swapping it out for a newer, more modern, AC style fan relay/controller could fix the problem. Does this sound right to anyone else?

How old are the furnace/AC systems are we working with? Mine is at least 40 years old. Installed 3 owners ago.

[92coyote]

Same issue. My fan is running constantly and electric bill was $320 this month. I have no clue how to fix it as nothing is working for me. 

[peacechild]

I replaced a sticking fan relay and that worked. I was able to also get a common wire wired in, but the relay was the problem. 

[Mrz]

SOLVED !!!! 

Simply go to the schedules. Click on the temperature and switch it to fan. Then make sure the option "Run every day" is enabled. That will then enable your fans to shut off when you shut off the whole system.

[Wilson_daniel94]

I got my nest through comed last winter.  Installed it before Christmas. It kept trying to test the A/C, but in winter the a/c doesn't want to work.  So I put the old thermostat back on because we were in a-20 cold snap.  Switched it back in the spring of 23, fan wouldn't stop.  At the time, my fan was going out, so I put the old thermostat back on. 

I figured, I put a new fan in,  it's summer,  the a/c is on most of the time, it's getting cool at night, so we should be running all systems now.  a/c during the day and heat at night. It's been fine the last few days, turning the unit off at night, opening the windows,  but tonight the fan didn't want to turn off again.  I was watching a movie(on the couch next to a register) and I was getting quite cold.  I checked the app before getting up, and it said it was off/ not running.  So I went into the app, said no fan schedule,  so I went to the wall unit. Went into the advanced settings, I'm not sure if this will be a problem,  but I disabled the fan function for the night to as what happens.  I am running tests as I type this.  Ran the fan manually through the app. Took 3 minutes to turn off from the time I stopped it. Going to have the windows open again tonight.  But I don't want any build-up of gas if the fan doesn't turn on.  If the a/c continues to run that's fine,  but if it gets too cold the furnace might kick on. It seems to be tamed, for now

[skipper168]

My Nest thermostat works fine for more than a year and this morning my wife complained the fan was running all night. I searched the internet and found this youtube video very helpful. https://www.youtube.com/watch?v=xNe-UxD4Egg

I ruled out the Nest thermostat, my problem was the reason #9 on the furnace control board: fan relay stuck closed. By smacking the fan relay gently with a screw driver handle, the fan relay switch opened and back to normal.

[LaurenK]

I am having the same problem. My unit has been in place for about 4 years. The first time it did this was maybe 6 months ago. I can’t recall what I did to get the fan to stop running because the fix I recalled finding is not working now. I tried taking off the nest screen and pulling the hard wires out, which means the hvac won’t run so yes the fan stops. But as soon as I reattach the Nest.. constant fan. From reading this it looks like there is no fix. Nest… are you going to do anything about this?

[Hippo42]

I'm having same issue here.  Was working for months then fan will not shut off.  Tried everything here...is there a fix?

[medina80]

I have a Goodman unit.  Started doing the same thing a year ago and it turned out to be the fan relay in the air handler. It is a Packard 380 Fan relay. 13 months later the same thing happened. I turned off the circuit breaker for 1 hour and turned it back on for enough time to cool the house. Did that a couple of times then just left it on and it worked. I am sure it is the same fan relay that is going bad. Probably burned contacts and sticking closed. I ordered the relay on-line for aboout $12.00

[LaurenK]

I have a Goodman also. I wonder if that could be my problem. I just had the HVAC out here twice. They didn't tell me the relay fan was bad... or did they? Oh, gosh it is too much to remember. Thanks for sharing this! How did you determine it was bad? 

[Wilson_daniel94]

Update from my post this summer.  I had gone into advanced settings and had the furnace running without the fan,  and I also disconnected the air conditioner wire from the baseplate of the next thermostat and it's been. Running fine since. 

I can't quite tell if it was the run furnace without fan iron.  Or unplugging the a/c. But the fan that I was mentioning wasn't the furnace fan not shutting off. It was the a/c. It was like they were both running simultaneously. 

I've since done a bit of research and I guess the thermostat uses the a/c as a heat pump? So, it was running the heat to warm the house then Aalborg immediately afterwards running the air to equalize the temperature? 

[medina80]

Some where on UTube I found someone who told me to jumper two pins and see if the relay worked. I also think that maybe other manufacturers are using the same fan relay. Goodman is now owned by a Japanese company.

[lesleygiles42]

the fan continue to run want shut off

[lesleygiles42]

what is my next option

[LynnDemers]

I am having the same issue.  The fan will not turn off.