How To Fix A Missing C Wire | Nest Thermostat Troubleshooting

[@clvanliew]

Thank you so much. This video is an absolute godsend. I’ve been sitting on my thermostat for 18 months trying to figure out why I couldn’t get it to work. It’s because my electrician he installed my HVAC system didn’t ever connect to the C wire and I was using an old battery powered thermostat so when I finally got the cover plate off my furnace I was able to get things put together really quickly.

[@rcisneros8567]

Tip - Take a picture of the old wires before disconnecting anything.

[@AlexanderTheGreat110]

^This^ I didn't and it was a lot of trial and error to get things back together

[@titusgray4598]

Also, if the wires are all the same color, or have different colors from the ones that normally are there, label the wires with their name.

[@danrook5757]

My house got renovated, buddy disconnected the wires and left them hanging

[@mkrchnak5269]

@@titusgray4598 .....most importantly, never install a smart thermostat. You give up control of your own heat/cooling, nest is the worst.

[@ipcamtalk4314]

@@mkrchnak5269 lol, you dont give up anything. Another clueless fool.. My smart thermostat does only what I tell it to do. That tinfoil hat looks funny.

[@jjjacer]

I got lucky when i added a smart thermostat, i didnt have a common wire connected, old thermostat used batteries, luckily i had an extra wire that was unused and i was able to find output on the furnace that was always 24v/common (didnt have a terminal for it), this saved me alot of pain as the wire had no play and couldnt tell if it went into the ceiling or if it went into the underside of the home (and being mobile home, both areas are not accessible as i would have to cut a hole in the ceiling or get under the trailer and open up the insulation under the beams.)

[@pubmeatman]

Must be nice to have that good of access to the control wire.

[@MrBp505]

If your replacement Thermostat is smaller than the old one, a trick you can use is to use a picture frame that is bigger than the old thermostat. You can mount some cork or decorative wood in the picture frame and mount the thermostat to that. Mount he whole thing to the wall.

[@dl6741]

That would look Hal assed . Cut a square hole. Place a 2x4 inside the hole and hold in place with a couple drywall screws, the insert a square piece of drywall and screw into the 2x4 and patch over with drywall tape and joint compound.

[@AdriansFix]

​😂😂😂😂 you should have just kept that to yourself @@dl6741

[@kommoncents0000]

I used a nest (2nd gen) where I used to live. I had only heat (oil) just a red, & white wire. The nest thermostat worked without a common wire and seemed to get charged for winter once the thermostat had constant activity from using the furnace. I found that it ran out of charge during the summer when there was no activity with the furnace. I then charged the thermostat by the micro USB port on the rear, off the wall, then put it back. The charge lasted quite a while and was OK till winter came. Some time later I added a 24V adapter that became my common wire.

[@bnasty267]

Yeah, some of those smart t-stats are tricky and 'steal' a little power through the R&W or R&Y leads when powering the heat/cool. As you mentioned, they can only do this when there's a call for the unit to run. Always better to have a C wire if possible, so it doesn't die unexpectedly.

[@sbfloyd5343]

Great video as usual- I suggest talking a photo of original connection on both ends

[@SeanBaker]

In my old apartment, I had four wires. In my house, I have five wires. Ecobee is the thermostat champ!!

[@markbeiser]

Good choice with the Ecobee, dodge the Nest garbage bullet.

[@SeanBaker]

@@markbeiser I had nest back in the apartment. It did what I needed. Once I got the house, I NEEDED those Ecobee room sensors.

[@Icant88]

I LOVE YOUR VIDEO.... I have a older home with an old thermostat that required a c wire... before returning the thermostat I wanted to keep/ and possibly update my home in the future.. I would have done this and keep my old therm

[@rolomaticz5009]

ALWAYS pull the wire UP, pulling down will get stuck in a small hole with the crap and debris inside the wall. This is very important in older homes with plaster lath walls!

[@eversonl6724]

Thank you! Your video helped me to change my 4 to 5 wire for a smart thermostat. Thanks again for your helpful information & tips.

[@cxspears]

Thank you so much. This video helped me fix my issue in less than 10 mins. The common wire was run through the wall but wasn’t hooked up at the control unit.

[@proxybox]

Nice fishing. What gets me is the installer didn't take the time to pull the clean wire to the thermostat like you did. Since it wasn't stapled down it was an easy fish up the vertical chase. It really gets me when so called "licensed HVAC technicians' take short cuts. There is a movement now for DIY to install their own mini-splits and split system heat pumps and the 'pros' get really defensive. Like all industries they have nothing to fear. In fact, they should embrace this since so many DIY will be calling them for repair once the systems break down after several years. It's not like they are renting VHS tapes and can get disintermediated

[@maritak]

Thank you! Was trying to confirm my blue wire was really the C wire - traced it back to inside the furnace and was able to confirm - YAY!

[@WizDumbDumb]

I have had this nest learning thermostat for over 3 years and it does save you money but it rarely turned on the second stage heating or cooling. Now this year it seems that my air conditioner compressor will not turn on at all. I am no expert by any means but I have been told that the way this thermostat is designed to work without a C wire and internal jumper for thr RH/ RC can cause major issues like mine to occur

[@jucnew]

This is exactly what I needed! Thanks!

[@EverydayHomeRepairs]

You bet!

[@ytsux9259]

It's easy when you can find the wire behind the wall. In my house, all the wires are "hidden", making the process much more complicated. And the distance from my thermostat to the heater is pretty far too.

[@Boswd]

I would say regardless of what the compatablilty chart for the Nest learning 3rd Gen (the more expensive one) says just get a C Wire installed or use an external C wire adapter. 2 wire systmes are too hit or miss in terms of issues arising, Just ignore and just make sure you have a C wire

[@iamamish]

Regarding the plate for the Nest, when I bought my Nest it came with a backplate for this exact scenario (the need to cover up the area previously covered by the old thermostat plate). I've got mine installed and will remove it when I paint the room.

[@tedlahm5740]

Use wago to connect red and white wire for HEAT, but how will that turn on the fan?

[@CantankerousDave]

The instructions in the Ecobee 4 thermostat I installed here nearly four years ago had instructions that were detailed enough even for this noob. It even came with a converter box to mount in the furnace if you needed the extra wire. Even had an extra jumbo backing plate if you needed extra coverage. Not the cheapest out there, but you get what you pay for.

[@bobstratton6362]

Ecobee is a way better Wifi stat then Nest ever was. They actually used HVAC engineers to design their's. Not like Apple. Yes, the first idea of a Nest T-stat was at Apple and got sold to Google.

[@Mike-cc3bc]

@@bobstratton6362 all opinion.

[@bobstratton6362]

@@Mike-cc3bc Well, if you do HVAC for a living, you can understand it better. I have installed many Nest and Ecobee stats and never had to remove a Ecobee. I have removed Nests. I personally had a Gen 2 and replaced it with a gen 3 and then replaced that with a Honeywell WiFi.

[@Mike-cc3bc]

@@bobstratton6362 I wasn't trying to be rude. I own a hvac company and have used all brands and had issues with all brands at one time or another. I prefer honeywell, I have friends who also have hvac companies and they prefer nest. It's all in what you prefer and believe to be best.

[@bobstratton6362]

@@Mike-cc3bc I understand. Google has did some things in the software that I personally wanted to override. the HIM tells you it is disabled but it is'n't really because their "Green Energy" mode over rides that. I also wanted to cycle the blower 4 times and hour for 5 minutes. Not allowed. You only have the option to do that once an hour as long as you like. In higher humidity, I just wanted to briefly circulate air but not make the call for cooling. So I guess it gets down to branding vs. pricing vs. options.

[@green5sing]

Amazing video. I am so thankful for your channel!!!

[@EverydayHomeRepairs]

Thanks, happy to help and we will keep the videos coming 👍

[@unclefreddieDied]

@@EverydayHomeRepairs awesome video! what if i don't have central a/c

[@Atlas.X9X]

Great video, clear and concise. Thanks for sharing.

[@AMMA-we3zz]

Excellent presentation

[@mcummings393]

Well this was best example of wires video I found , however my thermostat had 4 wires 2 red , 2 white. Lennox furnace the wires are tagged G, Y , W, RH. No wonder I can't figure this out. Lol

[@Sylvan_dB]

Yes, please leave a few inches service length on each end! When my furnace and thermostat were replaced a few years ago, they pulled it tight on both ends and there is ZERO free play. It is so annoying, I'm going to have to run a new wire to install my new thermostat.

[@ericelsberry5585]

Awesome video! Made it easy !

[@gilleslafreniere]

Hi! Thank you for the explanations. My furnace was not able to start the ventilator and furnace correctly. It successively tried to start the ventilator, would falter and try again successively in quite a number of times before succeeding to start properly. The correction to this problem, was to have a wire connected to the «C» (Common) connection on the thermostat from the furnace. Once the C wire was connected, the problem was solved. If you want some more explanations on this problem, see the explantations from the video. Good luck

[@waytospergtherebro]

You don't know what a ventilator is.

[@gilleslafreniere]

@@waytospergtherebro I think that the correct word is rather a "fan' indeed.

[@samsen3965]

Very informative. Thank you.

[@TARANS012]

Hey I had my old thermostat 4 wires . Red for 12v, Green for Ground, white for D and Yellow for C . I connected W for white , Y for yellow, G for green and R for red but I have no power now

[@twitter.comfixwifi992]

Wondering if the 24 volt wire and the C wire will handle 2 different thermostats? Guess I need a separate thermostat to operate my 2 wire furnace or use a (relay on the back up heat terminals on the thermostat that operates the heat pump)?

[@vincemorath676]

Great video. Thanks for sharing.

[@ismael-mm8gu]

Love the video, thank u

[@RonDyer-p1i]

Very Good. Thank You!!

[@hassanbazzi3545]

Very interesting. Thank you for sharing

[@dannyharpermusic]

Thanks for the video!

[@jaylmw08]

what about that jumper wire i saw. would you still need that there?

[@HenriZwols]

I installed a Nest thermostat a month ago. It only needed 2 wires between the thermostat and the 'Heat sink' module near the central heater.

[@n3tfury]

Great video, thanks!

[@beckthornley]

So your old wire has red white blue, so u connected only by splicing ( I BELIEVE it’s called that) the White and red, no more blue. Then u connected the new wires to just the white and red old and used just two colors on new. U used green and yellow, so the red and white went to which color? So now u don’t have any of the old wire?

[@cpvsgvmnt2116]

So I installed two smart thermostats.. downstairs one yesterday.. it's working. I did my upstairs one today.. same set of wires and same steps.. wires (RGYWC).. but upstairs no working. WTH?

[@imalilt]

Not sure who to ask, so I'm asking you. In my garage there's an outlet in the drywall, not in a box with conduit. I want to remove this outlet and put in a light switch. This switch will go in a metal junction box outside the drywall and covering the hole. I want to pull the wires from the box in the drywall into the new box. I'll then run conduit up to the ceiling where I will put a light. My question is how do I cover this hole with my metal box properly? If you know. Thanks.

[@etherealrose2139]

Drywall patch. Just KZbin it. For that size of a hole, you can probably buy a small patch kit rather than bulk materials unless you have other drywall projects.

[@JordynShoestock]

Need help setting mine up it's a 2 wire setup how do I do it

[@andyallison460]

Removing t-stat from wall makes running new wire much easier.

[@maxxmich]

do t use two different types of batteries.... use only 2 of the same kind.... ie.. alkine or zinc... not both

[@xenopac]

On my furnace borad it has no common option do i need a new board

[@abdullah_q8171]

Hi i have just 3 wires can i use G wire for C to install wifi thermostat ?

[@vperez007]

Thanks buddy

[@mozzer35]

Is the blue wire you mention at 4:01 usually the C wire? I’m trying to get power to my Amazon smart thermostat and I’ve hooked up the blue wire to C on my board. But I can’t get power. My board also isn’t exposed like a lot I’ve seen on KZbin.

[@nadiamagana2140]

I have a blue, green, red & what looks white. I had it connected to the nest & a/c would work. Trying to use the heater and it is not an option. Any help please?

[@asianmikedesigns]

This is what I have, running to 80's mercury type thermostat. Your wires are: red=24vac, blue=AC, white=Heater, green=blower fan. Need C=common to power thermostat without batteries. If you live in a house old enough to have telephone connections, this is where you can get (a whole bunch) 18 awg wire. I was installing a Honeywell programmable thermostat (not a smart) in a rental unit. Good luck.

[@MRSEMI]

MY FURNACE DOES NOT HAVE A CONTROL BOARD...(FROM 1975),...JUST A LOT OF WIRES WITH WIRE NUTS AND TAPE, LOTS OF THEM...THERMOSTAT HAS 4 WIRES, NO BLUE WIRE...CAN I JUST USE THE GREEN WIRE IN THE "C" SOCKET WITHOUT TOUCHING ANYTHING AT THE FURNACE?

[@bruceboma357]

Different batteries?

[@oneshot_onekill4618]

If my thermostat wire is damaged and i want to run a nest thermostat can i run an 18/8 wire

[@mikemount4411]

Yes

[@BashenManTV]

My old thermostat has a small naked wire going from the R to the Rc. So wiring my new thermostat just blows hot air.

[@adkchip1]

What do you do if your furnace does not have that circuit board? I have an airco oil fired furnace. There is a black block with terminals, but couldn’t detect voltage at any of them Does the unit have to be running?

[@mobitechaz]

Im stumped. Trying to install a smart tstat that requires a C wire. Ive got 29V from R to Y, G, O at my tstat. My R to C has 29v at the heat pump unit. I ran a blue wire from the C terminal at the heat pump unit down to the tstat. The other end of the same blue wire that reads 29v at the heat pump only reads 16 to 17v at the tstat end of the wire. WTF? What would cause the wire to lose 10 Volts? Its no longer than 7 feet of length (at least that's the physical distance from the tstat to the bryant heat pump unit on the roof. The connection to the C term is solid. There is continuity. Somehow, as that blue wire is snaking through the drywall down to the tstat it is losing 10 volts. I can't explain that. I tried a different wire, and same result. 17 volts. Makes no sense.

[@kellyleewright97]

I've learned that a base plate is available for these small nest units that cover the old paint etc. Now if I can just keep mine from blowing hot and cold at the same time......grrr.

[@robertwojtowicz933]

Good luck fishing the wire through the wall. Low-voltage wire supposed to be staple inside the wall to the studs

[@charaznable9328]

this is useful if u have gas heating

[@udreudre4372]

Call a hvac technician before trying to install a basic thermostat or a smart thermostat. I'm a technician its not worth the headache or the blown 3 amp control board fuse.

[@NYEK_GTR_]

Exactly… and if you do decide to make a attempt take pics of the wiring prior! It’s a pain when the wire colors for some reason don’t match the standard color chart and now you have to go up and down into the attic or stairs to trace what wire went where. Especially if there are splices along the way for some odd reason and changes colors. And keep your receipt and box just incase you have to return it.

[@jonnyz5772]

@@NYEK_GTR_ one can absolutely never assume the colours match - original installers at time of construction use whatever wire they have - mine is brown orange yellow green red blue - 6 wires - but no white lol - no choice but to check the terminals in the furnace and humidifier (along with taking photo of current screw terminals on the wall thermostat)

[@DevangThaker]

What I didn’t understand from this video is what if you have two thermostat to connect to, do you need to run two different wires to those thermostats and secondly, if you reused your current thermostat, why did you replace the wire? just because they were spliced up using a tape!!!

[@jamesgraham6796]

I think what confuses people is the fact that you already have a Red 24volt wire present, So why do I need another 24volt (Blue) wire ?

[@ODucks55]

Why limit yourself with only 5 wires. Run at least 18/8 wire. Also, when you use wire stripping pliers to remove the outer brown sheathing it’s possible to nick one of conductor wire and cause a short later on. Use the string inside to split open the brown sheath to expose the wires. If no string then pull one of the wires to do the same thing.

[@EverydayHomeRepairs]

Thanks for the feedback and agree the 18/8 would be a great option.

[@Bremend]

Now if only my hvac system had properly labeled terminals like that. I had to get a c wire adapter to plug in to an outlet

[@etherealrose2139]

A transformer has two taps. One will go, traditionally, to the red wire. Just piggy it into the other tap at the terminal. You don't actually need a labeled terminal block for it.

[@vitopriore3715]

i only have two wires coming from my oil furnace and no air condition how can i make a C wire?

[@jonnyz5772]

other commenters mentioned that they bought a 24 v ac transformer from amazon for exactly this purpose - hope you solved it

[@brandtfj]

be careful when replacing a thermostat you get the same type. my thermostat has a five-minute delay for the air conditioner compressor, if there is a glitch in the electric power supply

[@Tinuvier]

Nice

[@danyeldan2139]

I change my old thermostat to 3rd Gen Nest wires from the wall only 4 wires everything works but I don't have Airwave option in my Nest thermostat in my old thermostat I have that after I turn AC off fan will stay on for couple minute then turns off but with Nest as soon I turn off the AC shutdown the fans too

[@jonnyz5772]

it would makes sense the fan to run a few minutes after ac shut down as there is still so much cold available in the cooling unit

[@mmumambondo]

1:00 go me chalaging and security saturation when the gear is on 1:27

[@HVACPilot5100]

So.....explain how your AC was working considering there was no wire on G to turn the blower on

[@markbeiser]

Y and G could have been jumpered together at the indoor unit, old trick, just doesn't allow for running the fan by itself. Most heating systems don't need a separate call for fan with a call for heat.

[@Jo_Ro_Fulfil]

Why couldn't google include an easy connection within the $300 Nest Kit that I purchased even if it meant I needed to buy a separate transformer. This is a common problem that leaves people wanting to toss this $300 out a window but don't because it is $300. I don't want to become an HVAC expert. I've replaced thermostats before- straightforward.

[@MrPyorii]

Can you do a 100 amp sub panel

[@tjlovesrachel]

That’s easy bro… the hardest part is running the wire if nothing is open and you don’t want it exposed or have conduit seen loll

[@onthemarkdetailing8916]

What if there is no C wire coming from the outside unit to the panel?

[@jonnyz5772]

what outside unit to what panel?

[@kenthatfield]

Most importantly, turn off the power to the controller to prevent damage to the furnace controller and transformer power supply!!!

[@fmphotooffice5513]

Lucky you changed the thermostat before the alkaline cell left white crud on the battery case from combining it with that carbon cell. It can be a bummer scraping off that stuff. (joke)

[@gregb8759]

I called GOOGLE and they were fantastic

[@zoex100]

unrealistic.. 22 years of commercial tech in NYC... ez fix is use the resistor fuse that comes with t-stat.. cause ur not gonna run new wire 20 floors up... this is only reidentil application

[@leealtmansr.3811]

Please, always call a professional. You also didn't mention package units or heat pumps. As I tell students, the color codes for control voltage is a suggestion and always triple check. Also go with 7 wire for future updates, too.

[@scottiavarone6198]

Definitely always run spares.. Need 5 run 7 Need 7 or 8 run 10 etc.. in my opinion 18/2 should be outlawed .. lol

[@Octoear]

Dude this is basic knowledge for owning a home. At least it should be.

[@justinw9256]

Helps 0 if furnace has No control wire connect

[@michellezunnurain3555]

No wonder my nest was free. It worked fine for a year. Then suddenly e298 error.

[@raydogloc8127]

5Amp fuse

[@glpdrum]

Drop the Nest and get a Sensi, way better and cheaper.

[@dickburns1749]

As a hvac tech i feel the nest is the worst Tstat. Why would you run anything less than 18/10

[@Precisioninfrared]

Nest is a homeowners delight and a service techs junk!

[@markbeiser]

By far the most problematic WiFi thermostats in existence! And then there is that moronic "Airwave" feature, that is on by default...

[@lightworker6443]

👍🏻👍🏻👍🏻

[@acwright]

You mean a Can't C wire

[@tjlovesrachel]

Personally I think having any control of your home rigged to wifi is just absurd… I’m sticking with my digital non programmable … if I could find nice Mercury ones I’d have those.. I’m so sick of technology just ruining every aspect of everything it touches… now I know it’s gunna sound crazy… but I’m not anti technology… I’m just anti messing with a perfectly functioning system and complicating crap

[@mylo312]

I will say this you are at least write with explaining what color wires do what but you did not strip the wire properly you run the risk of shorting the wires out and there's a cool little thing called added wire if you cannot change your thermostat wire

[@patrick_kyker]

Just run a 5th wire.

[@franciscoruiz1452]

I lost my time here run a new wire 😱

[@scottkchong]

Thanks for the walk-through! Helped me fix the issue quickly for my Amazon thermostat that required a C-wire.

[@robertwojtowicz933]

Good luck fishing the wire through the wall. Low-voltage wire supposed to be staple inside the wall to the studs

[@sailor583]

I purchased a plug in, alternate current, 24V converter and ran wires to the smart thermostat. I plugged it in to the closest outlet to the thermostat needing a run of only like 4 ft of wires. It was a lot easier than trying to pick up 24 Volts from the Air Conditioning unit.

[@brianbendorf1383]

Where did you get the alternate current, 24v converter?

[@sailor583]

Amazon; note that the 24V converter is Alternating current (ac) and not dc.

[@michaeljavert4635]

I am looking for the old cloth wire and not finding it. I also prefer the good ole fashioned round Honeywell thermostat with mercury switch which I MIGHT find on E-bay. But as for cloth type thermostat wire, not finding it at all. They get rid of good stuff and replace it with junk, and leave us with junk. And batteries in a thermostat when there are low volts wires available, totally ridiculous.

[@integr8er66]

Replacing the wire is easy if the guy installing the previous thermostat wire didn't staple the wire inside the wall. Mine was of course, then you have to try to fish a tape through the wall.

[@danielruiz6565]

You can run a new t stat wire ... preferably an18/8 ...which gives you 8 different wires to work with

[@Balticblue93]

If you are going to do it, 18/8 or 18/6 are definitely better choices than 18/5. Gives you much more versatility down the road.

[@akalina]

I just pulled 18/8 wire to my Nest to support 2 stage heating/cooling and to support my AprilAir Humidifier. It was super easy.

[@EverydayHomeRepairs]

Dang! That is a pretty slick setup 👍

[@Andrew-wp1qh]

Tip… Don’t buy Nest.

[@HonestOK2930]

I just downgraded mine to a "dumb" thermostat because the "smart" thermostat kept messing up. Now it works flawless and how much control do you really need?

[@EverydayHomeRepairs]

There is something to be said for simplicity 👍

[@turtlepowersf]

I'm debating this....only that I would like to be able to control the temp from my phone. Looks like I'm going to have to run a new cable since they only ran 2-wire. Don't feel like crawling in my ceiling... might just go with a dumb system.

[@captaintruth3219]

Looks like you got a one legged ghost problem.

[@ericfraser7543]

The low voltage thermostat wire should not be sharing the same hole with Romex wire. 2:50

[@tracer740]

Eric- Are you inferring that 'induction interference' is possible?

[@ericfraser7543]

@@tracer740 no it is against the electric code. Thermost wire is not susceptible to noise. though Data wire Cat6 cable Rg6 or speaker wire you could pick up noise or reduce bandwidth.

[@tracer740]

@@ericfraser7543I'm sorry but I am missing your point. Are you inferring that the thermostat functions are transmitting 'radio' wave signals in their operation?

[@jessecavada3015]

Depends on the wire’s insulation barrier rating. The wire’s insulation barrier must meet or exceed the highest voltage. The guy in this video is a hack and therefore not a good idea to follow any advice in this video.

[@EverydayHomeRepairs]

Hey Jesse, thanks for the kind words. Nobody is begging you to stay subscribed to this channel. Wish you the best elsewhere and don’t let the door hit you on the way out ✌️

[@PapaGleb]

Tyvm for this. We just moved into a beautiful 90 yr old home and I have been working for month upgrading everything to modern. Just got to the thermo and realized getting the nest maybe impossible but now I see it’s not. Ty