topic Re: Nest wiring in Nest Thermostats

Nest wiring

Tlippy26 — Sun, 24 Apr 2022 13:44:37 GMT

I purchased a 3rd gen. Nest Learning thermostat. I took a pic of the wiring in my original thermostat (although there was a black wire not connected, just covered with electrical tape?!?). I do have a heat pump. My air conditioner worked fine prior to changing the thermostat but is now not blowing cold air it’s warm air. 😩 I made sure it was comparable prior to purchasing the nest. Any recommendations before I just remove the nest and return it? This is a pic of the original wiring and nest wiring.

Re: Nest wiring

MZellmer — Sun, 24 Apr 2022 15:52:10 GMT

If you have a heat pump, I think the labels for the wires should be those on the lower row of your original thermostat which is labeled "heat pump" (L to R: L, Aux/E, G, O/B, Y, R, Rc). This would make the orange wire the "O/B" lead (instead of W). From my experience without a heat pump (see my post elsewhere on the forum) I know that whenever there's a lead in the O/B terminal the Nest insists that you're connected to a heat pump which may be what you need. Haven't worked at all with heat pump systems, so don't know for sure, but it's probably worth a try.

Not sure what the black lead is for, but if you see a black lead not connected to anything where the thermostat wiring comes out in the heat pump control box, then you can bet that they used 6 conductor wire (including a black lead) when only 5 conductors were required.

Re: Nest wiring

Patrick_Caezza — Mon, 25 Apr 2022 00:22:08 GMT

Looks like you have a Heat Pump system.

Give this wiring a try

White - AUX/E to W2/AUX

Green - G to G

Orange - O/B to OB

Yellow - Y to Y1

Red - R to Rc (jumper to RC not needed)

Re: Nest wiring

MelbaDT — Fri, 29 Apr 2022 07:23:39 GMT

Hey folks,

Thanks again for the detailed wiring guide, Patrick_Caezza. I also appreciate your answer, MZellmer.

Tlippy26, how's your thermostat now? Have you tried wiring it just like the suggestion above?

Best,

Melba

Re: Nest wiring

MelbaDT — Tue, 03 May 2022 07:29:16 GMT

Hey Tlippy26,

Checking back in — still need our help?

Best,

Melba

Re: Nest wiring

MelbaDT — Tue, 10 May 2022 01:45:58 GMT

Hi,

I haven't heard from you in a while so I'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the community.

Best,

Melba