Nest Wiring Diagram 4 Wires 

For whatever reason my old thermostat had the W wire connected to the O/B terminal, even though I have a furnace. I copied this when installing the Nest and this caused issues. The Nest would default to the O connection which would turn the fan on and off, no heat. If I overrode that and set it to the B connection the heat would come on, but wouldn't turn off. After watching your explanation I connected the W wire to W1 on the Nest and everything seems to be working correctly. Thank you. You gave me exactly the information I need when you explained that O/B is for a heat pump.

Great video! I more or less knew where to connect each wire, but this gave me an understanding of each wire's use and made me a lot more confident in what I was about to do.🙂

Explained perfectly which answered all my questions regarding Rc vs Rh and whether I needed a Common. Happy to report it's working.

Excellent Explanation of the circuitry and operation of a thermostat

This a great video. I am having issues getting passed setup because it says the C wire is not connected true, but there are brand new batteries it. It says Find a Pro or leave setup. What do I do now? I have a Nest Smart.

Such a great video. I still can’t get my ac to kick on. I remember there’s something where every season we had to switch a wire so it would talk to furnace vs ac. Now that it’s summer, I’ve worked on it for hours and can’t figure it out. Nest chat couldn’t help either. Grey, white, green, red. Just found 5th black cord capped off and tucked back into wall. Any suggestions?

Is there a concern about not having a common wire causing issues with the AC unit?

Started having power issues on my 3rd Gen, replaced the internal battery and was good for about a week and problem came back. Ran a C wire and so far so good. I'm guessing my nest is starting to crap out. Had it for about 5yrs until issues.

Thank you. Which nest model is this?

I have a Ranco Dehumidistat wired into my current system. I believe it's simply a switch to control power to the thermostat based on humidity. Do I need to worry about this when seeing to my 4 wire system?

Great Video! But what if I have 4 wires but my original thermostat I didn’t have all 4 connected , only 3 - and what if the wires weren’t in color order for example the older thermostat had the green wire where it said W1 .. I connected the nest according to how the last thermostat was set up but I am not receiving any power.

Amazing video. Made perfect sense. Perfect amount of detail. So helpful. THANK YOU!!!!

Excellent video, made it simple for the non pro

Thanks for the detailed information, which is very helpful. My thermostat, A white-rogers, has both RH and RC wires. Shall I connect them to the RC and RH respectively? Or can I just connect my existing RH to the RH in the Nest thermostat (or RC to RC for that matter)?

The video gives really good understanding of all the connections, thanks you. In case the W1 terminal in Nest is faulty is it ok to connect to W2 instead. Will this cause more consumption or anything else.

What if I have four wires but 2 stage cooling and 2 stage heating will it still kick into second stage ?

Thank you so much for RC and RH I was so confused about that.

So with the 4 wire setup how common is it to actually need a c wire ? Because my unit is an older. Unit outside and the heater part runs of propane

I bought the Nest Thermostat which ideally requires 5 wires but my old thermostat that was installed when the house was built in 2003 only has 4 wires and some of the wire colours are different than what the Nest Thermostat calls for, so this is how I connected it: My four wires coming out of the wall are Red, Green, Black and Blue. So, I connected the red wire to R, the green wire to G, the blue wire to Y and the black wire to W.

Hi love this video but I have 4 wires and they are red, white, green and blue where would these go to on the nest?? My thermostat is the Lennox i Comfort smart thermostat and don't really like it and want to change to the Nest. And thank you for taking the time to answer my question. Michael

Really appreciate this video, THANK YOU. The renters in our property ripped the thermostat off the wall. We have red, black, white and green. Now that I know I can connect red with the others I can confirm our green is fan, white is heat and assuming black is cooling. Thanks again.

nice video!!! what keeps the display charged up on a nest E from 2019 ?

Can i install the nest power connector directly to the nest instead of my hvac?

I've got a question. I'm wanting to install a nest e thermostat with 4 wires but there is no yellow wire. Here's the current wiring. Red wire to rh with a jumper from rh-rc green wire to G, blue wire to Y , white wire to W. Do I hook up the nest E thermostat the same way without the jumper wire or?

I have a Google nest learning thermostat 4th generation can it be used for multiple heat sources?

I ran my wires as you said, I blue instead of yellow wire. The ac display does not show up. I noticed my ac condenser is connected to Y & C.

will this work for a variable speed fan/motor?

I have 2 wire coming from the HVAC system. At the thermostat there is an adapter with 2 wires going in, and 4 wires coming out. Will this work with nest?

My AC Heater Breaker keeps tripping, after that happens another breaker that supply’s power to my power Rc wire will trip. Once I flip them back on everything works fine for a short while. Any idea what it could be ? The heater breaker that keeps tripping is a quad pole 30/50 breaker and the second breaker is a quad pole 20/50. The first one only the 30A breakers are tripping the 50A is fine, but in the second one the 50A breaker is tripping. Both are are 240v and I’ve already replaced a couple parts inside my unit. I’m not sure if it’s the Nest unit or if it may need the C wire ? Any idea what it could be ?

very good video. very direct. no nonsense. thank you

With only having these 4 wires only, How can I disconnect the separate whole home humidifier wall box (which has 2 wires) where do those 2 wires go to connect it all to the nest?

I installed my gen 3 thermostats with a four wires based off my original thermostats. I did see a a fifth blue wire on both of my thermostat wiring harness. Should I connect the common wire to my circuit panel and both of my thermostats? Thank you for your help!

Hey so I’m in the Uk and looking to wall mount my nest e which requires a wiring base I can only find across the pond. It seems like I need Rh and w1 to power my heating but what powers would I find on these terminals?

Does it matter which wire you connect first??

My Nest does not seem to cool down my house when it is connected to the RH. There use to be a jumper between the RH and RC on the old thermostat. It’s not a AC problem. Since I just put the old thermostat back on and everything worked. Recently just switched out the wire from RH to RC. Hoping that it solves my problem. But then my concern is that my RC won’t heat up my house in the winter.

can you reference the video for how to install C wire please?

Hi! I live in Miami, so I don't need the heat option, should I connect it to the Rc Only? I have an issue with it, sometimes my outer unit seems to be on even if it is off in the nest. What should I do? Sorry if my question is confusing. Thanks!

okay, so, you keep saying you have videos for this and that, so why not post them in the description? or up on the top right in the video? i cant find some videos you say you have

I have a four wire system but furnace didn't have a Y post.

You save me from throughing it out the window. Thank you!

I have a four wired hvac. Installed the Nest in the spring and it operated the air conditioning just fine. Now that days are getting colder the gas furnace kicks in but we only get cold air coming through the vents. I read that disconnecting Y1 will allow the furnace to produce warm air. I tried this but no change, still getting cold air. Any ideas?

I have a blue wore instead of a yellow, does it do on C or Y1

if i have a nest thermostat model G4CVZ, can it still work with only 4 wires? I'm not sure if this video shows all nest thermostats or what and this video being from 2019, i'm not sure if things have changed since then.

My old thermostat has a flying wire from Y to W, what can I do in that scenario?

I have red, white, green and blue wired in my old thermostat and I want to connect nest thermostats how to go with color

How would you incorporate an air scrubber plus into this set up?

I just installed Nest E. Fan comes on for both furnace or AC but it will not kick on heat from the furnace. If I swap wires, the burner will kick on, but no fan. Any ideas? Nest Support can't figure it out.

What if you don't have a green wire but you have a blue wire? Also we connected it the way you said, except we put the blue wire into the C section of the Nest, because when it was in the G section it wouldn't turn on. Is it common that Green wire can be blue?

Thank you!

i have a 4 wire system but my colors are green yellow white red, how do i wire that up?

So I have a question for you. The guy that installed my ac and heat pump only used 4 of the 7 wires so do I follow this video to hook up my nest?

What about the 2 wires coming into the house from the outside air conditioner/compressor?

Hello, At my furnace, I have 2 sets of wires. One has 4 wires and the other has 2. 1st set Red - R White - W Green - G Black - Y 2nd set Black - Y White - C At the thermostat there’s only the 4 wires. Am I going to have any problems installing a nest thermostat with this wiring? I will add there is a humidifier connected to the HVAC. Thanks in advance!

Thank you.

My wires are labeled R, C, 1 and 2 on both my Thermostat and my furnace. Where do I plug 1 and 2??? Please help! I've been trying to setup my 3rd Gen Nest for 3 years and can't figure it out. I'm hungry and I need to go to the bathroom 😫

Need help I only have 3 wired red white and green I try to use the green for c wire what I need to do I have E298 no power

I have question i check the wiring its fine but i have set to heat but no reason half the time it blows cold air even though it does work on heat too. even in cold season it blows cold air.

I have a Dx + and a Dx - on the old thermostat and furnace. How do these translate to the new nest 3rd gen?

Excellent info

When I connect the red wire to the Rh terminal on Nest, my A/C unit keeps cutting off after 5 seconds. My Honeywell thermostat has a jumper wire between the R and Rc terminals, which I suspect is causing this issue. Any idea what might be going on, and how to fix this?

Thank you for the explication, I did it and work great.

How does this even work with no c wire hook up?

I have a Black, green, white and red. No yellow, what do I do?

ive seen wire G go into C, anything about that?

What if the burners for heating never come on?

Thank guys Your are awesome 👍

Helpful video. Thanks

I have all of the wires but not the green!!! Please help

Thank you so much!

Very Helpful.

Hey. Struggling trying to install one with 7 wires. Help? Multi-speed fan. Live in a new apartment.

What if u don't have a yellow wire

We have 4 wires labeled 1,2,3,4. I read online we can’t use Nest. Do you know if this is true?

what if my wires are not long enough?

Спасибо большое!!!!

What if you do not have a furnace??

As a floridian, we never say furnace. It is an a/c unit

Great video. I started panicking when I realized that my new home only had four wires compared to five like my apartment had.

I don’t have a yellow, I do have a black wire

Seriously how many times can you repeat R to Rh