topic Re: Wiring help Gen 3 wiring in Nest Thermostats

Wiring help Gen 3 wiring

Jfoo — Mon, 24 Apr 2023 20:39:15 GMT

Hello. I cannot get my 3rd gen nest learning thermostat to power up.

i have 5 wires on my old honeywell thermostat. W, Y, G, C and R/RC jumped.

anyway, i tried following directions.
W to W1

Y to Y1

G to G

C to C

jumped R/Rc to R

doesn't work. I have no power, wont turn on.
Am I doing it right?

Re: Wiring help Gen 3 wiring

MetalGlacier — Mon, 24 Apr 2023 20:46:36 GMT

It may just be that the thermostat battery is dead so try plugging a usb cable into the back and charge it for a couple of hours and try again.

Re: Wiring help Gen 3 wiring

Jfoo — Mon, 24 Apr 2023 21:02:21 GMT

Ok, let me charge it.

so, it needs battery to power up even when its installed?

Is my wiring correct?

Thanks!

Re: Wiring help Gen 3 wiring

Jfoo — Mon, 24 Apr 2023 22:03:55 GMT

I got it to turn on but its getting me an E79 error. I flipped the CB off and on, check the wires make sure they are inserted and still getting error.

Re: Wiring help Gen 3 wiring

CoolingWizard — Mon, 24 Apr 2023 22:37:45 GMT

An E79 error indicates the C wire is not receiving any power from the HVAC equipment transformer.

The AC Cooling Wizard

Re: Wiring help Gen 3 wiring

Markjosephp — Thu, 27 Apr 2023 20:10:19 GMT

Hello folks,

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

I appreciate your help, @CoolingWizard and @MetalGlacier.

@Jfoo, your common wire may not be properly grounded, so the system uses power sharing but doesn’t get enough energy. Try removing the C wire, leaving it disconnected, and restarting your thermostat after the changes. Also, please gather the power readings with and without the C wire under the Technical Info option.

Note: Turn off the power from your HVAC system at the breaker box before touching the wire.

Keep me posted on how it goes.

Regards,
Mark

Re: Wiring help Gen 3 wiring

Jake — Mon, 01 May 2023 18:30:21 GMT

Hey Jfoo,

I wanted to check in and see if you are still in need of any help. Please let me know, as I would be happy to assist, and answer any questions you may have.

Best regards,
Jake

Re: Wiring help Gen 3 wiring

Jake — Fri, 05 May 2023 17:01:29 GMT

Hey there,

I wanted to check in with you, and let you know that I will be locking the thread in 24 hours.

Best regards,

Jake