topic Re: Fan Runs Constantly in Nest Thermostats

Fan Runs Constantly

hummingbird — Sun, 09 Oct 2022 16:18:31 GMT

After working well for about 2 months, the fan started running continuously. The only way to stop it is to go up in the attic and manually turn off the air handler.

We had a repair person out who said the air handler is fine. He added the C wire which fixed the problem for about 2 days.

It's possible the relay switch on the air handler needs replacing, but we would like to fully trouble-shoot Nest issues before calling out for another repair visit.

Thank you.

Re: Fan Runs Constantly

Houptee — Sun, 09 Oct 2022 18:28:34 GMT

Remove the G wire at nest and see if it continues to run fan all the time.

If yes it is most likely the relay in the air handler.

You can replace it yourself as long as it is not built into the control board.

Take a picture of the air handler connections and the relay if you know what it looks like.

Re: Fan Runs Constantly

hummingbird — Sun, 09 Oct 2022 19:41:02 GMT

Thanks Houptee for the quick reply.

Earlier today I disconnected the whole device and the fan continued to run.

Re: Fan Runs Constantly

Houptee — Mon, 10 Oct 2022 14:23:50 GMT

If fan runs with no thermostat connected, and no wires touching, then you most likely need the fan relay inside the unit replaced.

But without seeing pics of the inside of the unit and the brand with model number I cannot determine what to tell you other than post some more pics.

Re: Fan Runs Constantly

Jhonleanmel — Wed, 12 Oct 2022 18:54:22 GMT

Hey folks,

Thanks again for helping here, @Houptee.
@hummingbird, I hope you've got the answer you're looking for. If you're still in need of any assistance, feel free to let us know.

Best,
Mel

Re: Fan Runs Constantly

hummingbird — Wed, 12 Oct 2022 19:32:29 GMT

Thanks - we're in a holding pattern for now. The unit is difficult to access so we're going to have a pro in to take a look at it. We'll follow up to let you know what they tell us so if others are having similar issues it will be documented here. Thanks!

Re: Fan Runs Constantly

Jhonleanmel — Thu, 13 Oct 2022 00:03:13 GMT

Hi hummingbird,

Thanks for letting us know. Take your time, I'll be waiting for your update.

Regards,
Mel

Re: Fan Runs Constantly

markemory1 — Sun, 16 Oct 2022 09:48:10 GMT

Any solution yet? I have the same issue with fan not turning off. Even with thermostat disconnected, but if I reinstall the old thermostat the fan works fine.

Re: Fan Runs Constantly

hummingbird — Tue, 18 Oct 2022 21:33:48 GMT

Hello!

The service technician we had out to look at the issue confirmed Hooptee's suspicion that the fan relay needs to be replaced. In our unit, that's built into the control panel. A control panel has been ordered and once it's installed I'll provide a hopefully final update.

Here's a summary for those who are trouble-shooting:

Nest Learning Thermostat installed and worked great for about 2 months until the fan ran continuously.

The C wire hadn't been connected so we connected it and at first thought the problem was resolved.

After a couple days, the fan continued to run continuously.

We removed the Nest thermostat and the fan still continued running.

The only way to turn off the fan was to disconnect power to the air handler.

The open question is whether the relay fan was nearing its end of life and it was just a coincidence it failed shortly after the Nest was installed without the C-wire or whether the constant running of the fan while there was no C-wire installed contributed to the failure.

Thank you all for your help, suggestions and follow-up. This is a valuable discussion board.

Re: Fan Runs Constantly

Jeff — Thu, 20 Oct 2022 15:12:12 GMT

Thanks for the detailed update, hummingbird. It sounds like you were able to get it all sorted out. We'll keep an eye on things for a couple of days to make sure all is well, but if anything comes up in the coming days, definitely let us know. Also, if you have any other needs, feel free to bring those up here.

Thanks,

Jeff

Re: Fan Runs Constantly

EmersonB — Sun, 23 Oct 2022 16:14:54 GMT

Hi everyone,

@hummingbird I'm dropping by to ensure that everything is covered here. I hope that sheds some light on the issue. If you have other questions and concerns, feel free to let me know.

I appreciate the help, @Houptee, @mel and @Jeff.

Regards,
Emerson

Re: Fan Runs Constantly

hummingbird — Sun, 23 Oct 2022 16:41:14 GMT

Hi Emerson,

We're in holding mode at the moment.

A new control panel has been ordered so we're waiting for it to arrive.

I'll post a follow-up update once that's completed.

I greatly appreciate the help from the community.

We were scrambling in crisis mode when I originally posted and @Houptee replied within hours - and I think it was on a weekend. His troubleshooting advice was spot-on and greatly appreciated.

The follow up from Community Specialists is also appreciated.

Thank you!

Hummingbird

Re: Fan Runs Constantly

EmersonB — Tue, 25 Oct 2022 17:21:15 GMT

Hello hummingbird,

Thanks for letting us know. Take your time, I'll be waiting for your update.

Best,
Emerson

Re: Fan Runs Constantly

EmersonB — Fri, 28 Oct 2022 18:02:47 GMT

Hi hummingbird,

How's it going with your fan? Have you received your control panel order?

Keep us posted.

Thanks,
Emerson

Re: Fan Runs Constantly

hummingbird — Fri, 28 Oct 2022 23:23:24 GMT

Hello! Thanks for checking in about our progress.

If all goes according to plan, the new panel will be installed Monday.

Thanks - Hummingbird

Re: Fan Runs Constantly

EmersonB — Fri, 28 Oct 2022 23:42:20 GMT

Hey hummingbird,

Thanks for getting back to us. Sounds like a plan. Keep us posted.

Best,
Emerson

Re: Fan Runs Constantly

Markjosephp — Tue, 01 Nov 2022 12:50:16 GMT

Hello hummingbird,

I wanted to follow up and see if you are still in need of any help. Is your new control panel already installed? How's it going so far?

Best regards,

Mark

Re: Fan Runs Constantly

hummingbird — Tue, 01 Nov 2022 16:25:19 GMT

Hello!

The new control panel was installed yesterday and now the fan turns on/off correctly.

For those who are troubleshooting - the air handler relay switch was the problem.

On our unit, the relay switch is embedded in the control panel, so the control panel was replaced.

Thanks to @Houptee and the community specialists who have been providing support.

All the best to you all - Hummingbird

Re: Fan Runs Constantly

Markjosephp — Tue, 01 Nov 2022 18:18:13 GMT

Hi hummingbird,

That sounds great! Thanks for getting back and letting us know how installing a new control panel was able to resolve your concern. Big help!

So I'm going to lock this thread in 24 hours unless you have other questions or concerns.

Best regards,

Mark

Re: Fan Runs Constantly

markemory1 — Wed, 02 Nov 2022 04:37:56 GMT

I still have not been helped.