topic Re: AC unit randomly turns on in heat mode in Nest Thermostats

AC unit randomly turns on in heat mode

Post — Fri, 12 May 2023 01:30:03 GMT

My AC unit is randomly turning on, even while in heat mode. For example, my heat is set to 67, the current temp is 77, but the unit turned on. It didn't stay on though (e.g., to cool to 67). Otherwise, my heat and AC turn on when they are supposed to based on the temperature settings.

Re: AC unit randomly turns on in heat mode

Patrick_Caezza — Fri, 12 May 2023 01:35:40 GMT

Is this a new install or one that has been working and now has problems?

How is the Nest wired? Can you post a picture of the wiring?

Do you still have a picture of the original thermostat wiring that you can post?

Re: AC unit randomly turns on in heat mode

Post — Fri, 12 May 2023 02:28:40 GMT

Relatively new. Installed around 6-8 months ago.

Don't have the original wiring picture, but attached is the Nest wiring.

Re: AC unit randomly turns on in heat mode

Patrick_Caezza — Fri, 12 May 2023 04:26:31 GMT

@Post

Are there any other wires behind the base that are not in use?

Do you have access to the furnace? If you do, can you post a picture of the terminal block on the control board?

Re: AC unit randomly turns on in heat mode

Post — Sat, 13 May 2023 22:18:28 GMT

@Patrick_Caezza

I don't think there are other wires behind the base not in use.

Not sure where the control board is, but took some pictures of where the wires are attached.

Thanks,

Re: AC unit randomly turns on in heat mode

Patrick_Caezza — Sun, 14 May 2023 04:47:16 GMT

@Post

Not all systems have a control board.

Try tracing the thermostat cable into the unit and see if the thermostat wires are wire nutted to the unit's wiring.

What is the manufacturer and model number for the furnace?

Re: AC unit randomly turns on in heat mode

Post — Mon, 15 May 2023 15:27:01 GMT

@Patrick_Caezza

The furnace is a Carrier. Here is a photo of the model #.

Not sure what you mean by, "Try tracing the thermostat cable into the unit and see if the thermostat wires are wire nutted to the unit's wiring." I can trace the wires from the thermostat, but what do you mean by are they wire nutted to the unit's wiring?

Thanks,

Re: AC unit randomly turns on in heat mode

Markjosephp — Thu, 18 May 2023 18:58:44 GMT

Hi everyone,

I wanted to stop by and see how I could help.

Thanks for looking into this. @Patrick_Caezza.

@Post, I appreciate you sharing the photos. In most cases, the control board can be found at your furnace or air handler. In addition to what was mentioned by Patrick_Caezza, you might see a twist-on connector or wire connector connecting the wires from your thermostat, leading you directly to the circuit board. Can you share with us a clear photo of your system's make and model?

Regards,

Mark

Re: AC unit randomly turns on in heat mode

Dan_A — Sun, 21 May 2023 19:00:27 GMT

Hey there,

I wanted to follow up and see if you still need help. Please let me know if you are still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Best,

Dan

Re: AC unit randomly turns on in heat mode

Dan_A — Mon, 22 May 2023 19:32:01 GMT

Hey there Post,

It's been a few days since your last reply — we're going to lock the thread within 24 hours. If you have further concerns, please feel free to create a new post.

Cheers,

Dan

Re: AC unit randomly turns on in heat mode

Post — Mon, 22 May 2023 19:57:08 GMT

Haven't been home for a couple of days. Will check the board and send new photo later today.

Jay

Re: AC unit randomly turns on in heat mode

Dan_A — Wed, 24 May 2023 01:29:27 GMT

Hey there Post,

Sounds like a plan! I’ll keep this thread open and wait for your update. Let us know how it goes.

Kind regards,

Dan

Re: AC unit randomly turns on in heat mode

Markjosephp — Sat, 27 May 2023 16:01:51 GMT

Hello Jay,

I'm checking back in — how's it going? Still need our help?

Regards,

Mark

Re: AC unit randomly turns on in heat mode

zoeuvre — Tue, 30 May 2023 18:00:53 GMT

Hello everyone,

@Post, we haven't heard from you in a while so we'll be locking this thread if there is no update within 24 hours. If you run into any more issues in the future, please feel free to create a new thread.

All the best,

Zoe