Thermostat Wiring at Control Boards

[@josephbelcher2834]

Thought I was going to have to return my Nest thermostat because old one had RH/RC with jumper. Watched this video and took a look at the wiring on the control board and realized I didn't have to return it. Thanks!

[@davidadowlen]

Appreciate the information. You are a good teacher. That is a skill. Many have information and knowledge but cant explain things in a way most can understand. Thank you!

[@JerseyMikeHVAC]

You're very welcome.

[@tedthisius4778]

I found the video very informative and superior to other videos I have watched. For me the big take away was that the color of the wires might or might not agree with the letter markings on the components. It is the function that is important. One take away from another video is that when replacing a thermostat that has been working but has failed is to take a picture of the previous wiring to use as a reference. I have a thermostat where the DOWN button does not reliably reduce the temperature setting so I am going to replace it with a simple manual Heat/Cool type thermostat. I plan to take a picture first and connect the wires to the same "Letters" as in the picture.

[@jameszandian6042]

You do an excellent job explaining every key aspect of wiring. Best I have seen on the KZbin.

[@Cowboy_Ash]

This is the most intelligent explanation of thermostat and control board wiring. Thank you Sir.

[@osvaldoramirez1857]

Finally, someone who can explain something from the inside out. Totally, understandable. I've looked many places for this info. and had to put it together myself to understand, what Mike has explained soo... clearly .Great job, Mike. Thank you.

[@JerseyMikeHVAC]

Glad it was helpful!

[@FiligreedSpeaker]

I knew nothing of HVAC, though wanted to figure it out some since I just moved the thermostat by running a new length of 5 conductor. Everything worked fine, but I had a piece of 2 conductor coming off of it that I now know the function of thanks to this video. You explained all of the functions of the connection in a manner that people could understand easily and clearly without treating us like idiots. Thank you!!!

[@JerseyMikeHVAC]

You're welcome

[@cpaul57]

Your channel teaches more than most trade schools. Far better info than somerset county tech. That school was a waste.

[@jcgarayjr]

Very good explanation without all of the 'self advertising'. Excellent channel.

[@mxcollin95]

This video is gold. Three of your videos have saved me thousands of dollars and I can’t thank you enough man! 👍

[@JerseyMikeHVAC]

That's crazy! Glad to help.

[@rbm8218]

Finally how to wire a thermostat and how it works explained so it's easy to understand. I've been looking for a video like this for years! They should show this video in heating and cooling classes. Thank You!

[@CidZombie]

The most important advice I ever received in my yeasr so far as an electrician is to never let the magic smoke out of the wires

[@JerseyMikeHVAC]

Thats pretty good advice.

[@phillipdavis8222]

Lol

[@mangowalklyrics1339]

Excellent and concise explanation of the functional relationship between the t’stat and the furnace control board.👍

[@JerseyMikeHVAC]

Thanks!

[@ismugo]

Excellent explanation, I watched many videos until I finally got to understand it with yours. Kudos!

[@steverusso177]

Best explanation I have seen for beginners.

[@asoteico9528]

Best explanation about Rc and Rh ever seen !!! Thanks!

[@JerseyMikeHVAC]

No problem! THanks for the comment.

[@jollyscaria1922]

Rc 24v rh heating

[@anthonyroy4750]

I had a very old and very confusing wiring setup on my old thermostat/control board with a wire splice in the middle too. This helped me get it sorted out and understand why it was wired the way it was. New smart thermostat is in and functioning perfectly. Thank you!!!

[@JerseyMikeHVAC]

Glad it helped!

[@migueldominguez7962]

I love your videos!! They are the most educational on KZbin. I really appreciate it. I am a young apprentice starting out in the trade.

[@JerseyMikeHVAC]

Glad to help

[@mikemckeon8562]

Excellent video. How do I connect a thermostat with NC, NO, COM to a control board with R W and C (24v power)?

[@wz222]

Great video. Learned a lot, thank you.

[@ricktroup]

Great explanation. Easy to understand and follow. Thank You.

[@skypallman6169]

You can tell when someone is a G at what they do when they lay it down like this! Majority of the time wiring is just 1 point 2 another and ends up making sense at the end of the day. But having someone lay it out like this it sure does make it easier to learn.

[@JerseyMikeHVAC]

Thank you, brother.

[@yanshein4042]

The best explanation of thermostat wiring. Thank you for educating me, Sir

[@JerseyMikeHVAC]

Glad it helped

[@frankfrank9711]

Omg, this is a blessing video. I now know exactly what to do with my separate cool and heat systems. Thank YOU!

[@ashwinbhayani4273]

I really learned the basic of wiring to day very well. Thank you so much . Best tutorial 👌👍

[@JerseyMikeHVAC]

Glad it helped

[@Knightransport]

You have a TALENT for teaching, this is exactly what i needed and I understood everything. Thank you so much bro!!

[@WPF465B]

Excellent information. Thank you.

[@curiousgeorge88]

This video is awesome‼️ I just wanted to say thank you so much for making it!!!! because of this video I wired two AC systems in my house with a Wi-Fi setup and they are working perfectly!‼️🍻👍🏻👍🏻

[@JerseyMikeHVAC]

Good job.

[@Nicole-dj3jf]

Got the same stat my wire is pink no idea they are the same Honeywell new one has more buttons almost 200 bucks I don't wanna f it up ugh

[@georgebrodie9795]

Hey Mike just wanted to thank you for the information. I enjoy your videos and think they are some of the best ones out there. Thanks again

[@JerseyMikeHVAC]

You're very welcome.

[@BillMaher-e5g]

Best explanation I have ever seen on this subject. Thank you.

[@JerseyMikeHVAC]

You're welcome!

[@lilalex4194]

I’ve been installing in California for about a year now, you’re videos have helped my whole journey. thanks brother

[@JerseyMikeHVAC]

Just letting me know that helps my journey too. Thank you brother.

[@eaglebill3738]

Very well done! Very clear and concise explanation. Great job!

[@RingleberryMcFinklestein]

"You're gonna let some smoke out of a lot of components ." Had me rollin 😆 thanks

[@chains350]

Thanks so much for this video! This is exactly what I was looking for. This really explains everything. I have 2 systems with 2 different transformers but maybe you can include using a “relay in a box” to keep them separated when your thermostat only has a single “r” terminal.

[@roberthosking7524]

That was quite informative. I have a diesel heater which has its own sort of thermostat. By sort of I mean when it reaches a certain temperature it just goes to the lowest setting. They make programmable thermostats that can intercept the wireless control signal for the diesel heater and use it to manipulate the off and on buttons. This allows a person to have an actual thermostat that turns the unit off when it reaches temperature. The concept is quite simple but the aftermarket thermostat is an additional $50. Some folks wire up a standard furnace thermostat to the contact points of the diesel heater's remote switch and use a 12-volt power supply to send a signal (power) to the diesel heater's remote switch. The diesel heater remote switch will time out after 10 seconds, so they can send power to the on button to turn the unit on and when the room temperature is satisfied it sends power to the off button. It seems to me this could be accomplished without a separate 12 volt power supply. I'm not really sure but I'll have to watch your video a few more times to see if a regular thermostat can trigger (close) one circuit (on) when it needs heat and close another circuit (off) when it reaches temperature and is ready to shut down the machine (essentially activating the off button on the diesel heater remote). Your explanations were very clear and I appreciate your professional knowledge. Thanks.

[@JerseyMikeHVAC]

I just bought a relay that can work with 12-24 volts ac or DC. With that you can run a regular tstat off of a 24 circuit to activate the relay and send 12vdc to the switching side of the relay to control the heater. Normally open and normally closed can be used to toggle.

[@roberthosking7524]

​@@JerseyMikeHVAC I also have a couple of those small relays that I used to trigger my plasma cutter when I built a CNC table for it. It's a normally open and closes the contact when it receives a power signal. I was trying to rattle my marbles together to figure out how to incorporate that device. For me it usually takes quite some time before my brain can wrap around how everything works. I know the solution is there somewhere I just have to comprehend it. Thanks for the reply.

[@guytas]

Super clear explanation. I was hoping you were going to talk about that “different animal”… the heat pump wiring…

[@JerseyMikeHVAC]

I have several videos where I get deep into that. kzbin.info/www/bejne/lWSbpWCIhc53ras kzbin.info/www/bejne/nXOtq4mMbMugla8 kzbin.info/www/bejne/fGmbimyEoNunh9k kzbin.info/www/bejne/d364hmZ7hpikgtU

[@ANARCHYTOORDER]

Love u say r to r etc takes priority over color code, cause I had someone wire an air conditioner in 2002 who thought it was 1950 apparently used blue for power gave me a massive headache till i spent hours ohming it out to find out was connected to the r terminal

[@JerseyMikeHVAC]

Yup. Had one situation where somebody ran 3 sets of 2 wire instead of just running one 6 wire. All of the wires were just red and white.

[@danojj700]

Best explanation I have come across🎉🎉🎉🎉

[@marks8052]

Thx for your informative vids keep ‘em coming. Did you do a video on correct wiring for a 2 stage furnace?

[@removebeforeflight7365]

This is very informative and consolidated my knowledge of the wiring. This pretty much describes the same wiring as my Goodman furnace/ac setup. The only difference is my G terminal is wired to an external switch system that controls my central exhaust fan (R and G). Whenever I turn on a bathroom fan switch, it turns on my central exhaust fan but also turns on my blower motor through some kind of relay. I wonder if I can still connect another G wire from my thermostat to the G terminal to be able to use the circulation feature while still having my exhaust fan system wired to the blower as well...

[@sleeve8651]

What I have found, is that HVAC Guys do what they want, when possible ! Not sure what they're thinking is, but likely as long as the same wire is connected to the Thermostat, and then to the control board, thats all that matters, apparently to them ! It's as if, they make it their own ! Especially if they do the installation ! As if they will be the only ones to service the system ! I found this out the hard way ! Thinking I could do a quick and simple Thermostat change ! Fortunately I was smart enough to take a before picture with my phone, of the wiring scheme ! Which turned out to be a Life saver ! I didn't agree with what I saw, but took the, " When in Rome " stance ! Most importantly, it worked, and you can't argue with success ! I can think of a lot of names for the initial install, but not here ! 😂🤣😂

[@yanshein4042]

I would give this videos 10 thumbs up if there is such option.

[@ws9691]

Excellent description - Thank You Jersey Mike!!

[@johndouglas3724]

Thank you Sir, you made this easy to understand...

[@unabridgeddick6645]

You are an awesome teacher. Thanks for this.

[@JerseyMikeHVAC]

You're welcome

[@That_40yrOld_Dad]

By far the best video I've watched on how to wire a furnace. I wish that I could do a video call with you because I had a circuit board that went bad and one next door out of a furnace that was free and I'm trying to wire it up and make it work except it's a little bit different then the circuit board that is smoked. The only thing I wish your video had also is how each of the other components turn on and what sequence is used and possibly what the ohms are for each sensor. Kinda know what I'm doing, but first time fucking with furnace. Also GF is cold. Really good video, and I will be subscribing

[@JacksLore]

Simple to the point clear explanation

[@JoseGarcia-k8v1s]

Great job as usual mike, keep up the great work

[@JohnDoe-e4h3h]

Explained very well 👏

[@gotchaplumber]

Mike, is the orders: 1.transformer powers board, 2. Red wire is the only wire energized to thermostat 3.other wires are energized returning to board according to call. Is "red" wire only supply voltage to thermostat? Could u do a video on low voltage side of transformer supplying voltage to board? Is my thinking correct or incorrect? Thank you for good videos!

[@jimross2101]

It is not always true you need a green wire (G terminal) to turn on the fan (blower) to accompany your furnace in the heating cycle. This can be setup inside the furnace and can be totally controlled by the wall thermostat with only 2 wires. Typically red (Rc) and white (W) are the only connections necessary. Also, you should probably point out that "24 volts" is actually 24 volts AC (alternating current). Also, you speak of 3 wires to the outdoor condenser but talk only about 2 wires, which is a connection for A/C. The 3rd wire is for the reversing valve for a heat pump system.

[@jrh86]

Exceptional tutorial very helpfull and easy to follow.

[@MrRicow89]

I have a control board like the one you're mentioning in your video, how do I connect my Nest power connector to my furnace if I don't have a terminal block on my control board?

[@BCrooks56]

This video is absolutely awesome.

[@keiththomas8720]

I set my thermostat to heat mode. Adjust thermostat to 70° furnace. Lights comes on blows heat into the house reaches setpoint turns off, but does not continue to run and blow access heat out of the heat exchanger and trips on high limit. Is my problem control board or thermostat.

[@MichaelKissane-h4n]

wow ,super informative. .that totally put my brain at ease..gonna tackle thermostat now.that i understand., thank you for that great video my man

[@JerseyMikeHVAC]

No problem

[@lordvader2681]

Very informative video !! Definitely been explained here the best that I have heard unfortunately it doesn't answer the question that I am in pursuit of which is for a dual stage blower motor. I have been looking all over the place and cant figure it out i'm already three hours down the rabbit hole ...*( and no money to call an AC tec to fix ...

[@JerseyMikeHVAC]

What exactly are you trying to figure out and what is the model # system do you have?

[@lordvader2681]

@@JerseyMikeHVAC how can I email you with pictures ??

[@JerseyMikeHVAC]

@@lordvader2681 [e-mail]

[@WarrenHenry]

Thank you for this! Totally understand it now. Thanks again

[@JerseyMikeHVAC]

No problem

[@mitchblackwood]

thank you for the video,im trying to hook up a honeywell t9 on my older lennox ac unit and am having a hard time

[@gotchaplumber]

Great explanation!

[@guns-usa8564]

Would it be best to verify the furnace at the board? Take a picture of the wiring then apply it to the thermostat for correct wiring?

[@JerseyMikeHVAC]

Absolutely. Yes. You just have to be careful because terminals at the board can have wires from other places than the thermostat (like a condensing unit or a humidifier, for example) so just make sure you know which collection of wires actually go to the thermostat.

[@guns-usa8564]

The circuit board at the furnace wouldn’t lie as long as you’re reading the right part of the circuit board connections I would think and you have 2 wires at the contractor that’s your 24 volts to turn on your outside unit witch causes your contactor to complete the circuit you should be a professor 👍

[@JerseyMikeHVAC]

Yes sir. You got it.

[@guns-usa8564]

No thank you boss

[@samshepard8234]

Hello I have a problem. The colors on the wires have been worn out so they are all the same brownish orange color. Except the red wire. My furnace is for both HVAC Unit. Don't know how to change them.

[@JerseyMikeHVAC]

What are you changing?

[@samshepard8234]

I will be changing the thermostat tomorrow when it arrives. I took a look in the thermostat and realized some of the wires are old and worn out so the colors are worn out. Except the red one. Still functions well.

[@JerseyMikeHVAC]

@@samshepard8234 best thing is to just label each wire according to what terminal it lands on and use the same terminals on the new stat. or, if there is enough slack in the wire, you can pull it out and pull back the outer jacket to where it isn't faded.

[@samshepard8234]

Good idea I'll try that. Thanks a lot for your advice!

[@2979paul]

Awesome video

[@JerseyMikeHVAC]

Thanks!

[@bikbik8446]

Excellent job

[@nomadLife2025]

Hi was wondering if you can help me with finding a thermostat on my rv I have the RH RC not to sure what to look for and I’ve been told to get a programmable thermostat

[@rikjamezmartinez9316]

Great video better then most i appreciate this 💯👍

[@JerseyMikeHVAC]

Thank you. Appreciate you.

[@rondrene5420]

Just started watching your videos really enjoyed the content love this channel already

[@JerseyMikeHVAC]

Awesome! Thank you.

[@dj5752]

Great video. I have the RC RH Separate system with no jumper wire as you stated. If I wanted to add a common wire because there is none connected to my thermostat now for the purpose of installing a smart thermostat. How can I go about doing that? Thanks.

[@JerseyMikeHVAC]

Most smart thermostats working on 2 transformer set ups like yours will charge off of the cooling system (Rc terminal and Common). You'll want to see if you have an unused wire on the thermostat wires from your AC system and use that as a common connection between the AC control board and thermostat. FYI, for Ecobees the PEK kit will not work on a 2 transformer system if you don't have a common wire available.

[@dj5752]

@@JerseyMikeHVAC I'll look to see if a common wire is present. Thank you.

[@david88va]

This just made it click! Ty my friend

[@JerseyMikeHVAC]

You're welcome

[@AZ_sunshine]

thanks - very detailed, interesting and informative.

[@bonduie4414]

Damn you are good! thanks

[@Afghanistani_1]

Informative video, thank you 💡

[@JerseyMikeHVAC]

My pleasure!

[@tamilowman5645]

I have a 5 wire older system that I'd like to connect to a newer smart thermostat. You gave an excellent description of the Rc and Rh wires, however I have a red wire to Rh and blue wire to Rc. Blue wire I assumed was a Control wire but I feel I should follow the existing configuration. Without a control wire, this limits my options for a smart thermostat, unless i want to add the Control. Is the configuration of my wires correct to follow as is, with blue to Rc? Thank you.

[@JerseyMikeHVAC]

Yes. Wire it the same way. All the blue wire means is that the original technician who wired it decided to use blue for AC control power (to Rc terminal) to distinguish it from the red for heating power (to Rh terminal).

[@LeslieWood-qb8do]

Well done j m 👍❤️🙏

[@JerseyMikeHVAC]

Thank you

[@FruitiiLoops]

The control board in my air handler doesn’t have a yellow wire or yellow terminal. It’s just R C G W2 W1

[@FruitiiLoops]

How would I connect my fan?

[@JerseyMikeHVAC]

On some models the Y wire from the thermostat runs directly to the outside unit and doesn't go to the control board on the indoor unit. Once it activates the outdoor contactor to turn the outdoor unit on, the Y wires returns back to the indoor unit as a common wire connected to C.

[@AmaWilk]

Outstanding video.

[@georgebrodie9795]

Hey Jersey Mike enjoy your videos very much. Very informative but I do have a question about the rc and rh terminal which I do understand about heating and cooling. I have two zone heating gas hot water baseboard with a heating only two wire thermostat down stairs and my other thermostat upstairs is heating and cooling with unit in attic . My question Mike is this the upstairs thermostat is wired as this I have a red wire on my rc for cooling and a red wire on w then I have a white wire on r which would be for heat then I have a yellow wire on y and then a green wire on g . Everything seems to be working fine except when I turn on cooling my fan is set to auto which comes on automatically I don’t believe I can just run my fan independently. If I put in a nest thermostat should I put the two red wires to rc and rh and put the white wire to w if everything seems to be running okay.

[@georgebrodie9795]

Or should I wire up the nest thermostat the way it’s wired up now. Any help I would appreciate

[@JerseyMikeHVAC]

All they did was reverse the red and white for heating, but you're just closing a simple circuit so it doesn't matter. You can keep the wiring as is or switch the red and white so the white goes to W and the red to Rh (which is conventional color code wiring). Only thing with the nest is that if it needs a common wire that common has to come off the AC system, not the boiler. Nests charge off of the Rc.

[@whitetiger5570]

My system is a forced air & heating system and my old thermostat (non-progamable) has a jumper wire connected to Rc/RH. My new non-programable Emerson 80 series 1F83C-11NP thermostat came with a tiny jumper wire already connected to the board of the thermostat. Can I just throw the old jumper wire out or do I cut the new jumper wire and use the old one on the new connectors or it doesn't matter which jumper wire gets used? I'm thinking it doesn't matter which one I use based on this video and others I have come across.

[@JerseyMikeHVAC]

You shouldn't need to remove the jumper in the new stat in favor of the old one. They serve the same purpose.

[@whitetiger5570]

@@JerseyMikeHVAC Thank you, that's what I thought

[@reynaldosilva8377]

Very helpful video thanks Mike🎉🎉🎉

[@JerseyMikeHVAC]

No problem!

[@yutube1452]

My control board doesn't have a wire connected to Y. I have central ac and furance. I only have wires for W R G C. Why is that ?

[@JerseyMikeHVAC]

There are some systems that send the Y signal for cooling straight out to the condensing unit outside and it comes back to the air handler as a common.

[@MixVideo30]

In furnaces w1 black and w2 white wire so in google tharmostat gen3 w1 black and w2 connect ?

[@JerseyMikeHVAC]

Yes, black was used for 1st stage heat and white for second stage.

[@MixVideo30]

@JerseyMikeHVAC okay Thank you

[@Dave-ld3dr]

Question - I do not have a C wire to my knowledge in my thermostat wiring.I have the white wire but it is hooked up to the W.My thermostat right now is battery operated.In my furnace I do have a white wire connected to the C slot.So do I have a common wire for power for a smart thermostat?I have a red to RV.A black to R.White to W or O/B.Another black to Y and a green to G in my existing thermostat.C is empty but again in the furnace a white is hooked up to the C.

[@JerseyMikeHVAC]

The white wire on C at the furnace is likely from the outdoor AC unit. Although it is a common, it is not for your thermostat. So, no, you don't have a common wire available for a smart stat. You only have what's physically available at the thermostat's location itself. If you did have a common wire available at the thermostat, that C terminal in the furnace is where it would connect, however.

[@Dave-ld3dr]

I did read that I could change my green wire at the thermostat to the C & move the Green at the furnace to the White C & put a jumper where the green originally was.Does that sound correct?

[@JerseyMikeHVAC]

It's possible to sub the G wire as a common, but it depends on what kind of system you have. With a jumper between Y and G it could likely work.

[@Dave-ld3dr]

​​⁠I can only try.My fear is I don’t want to mess with the furnace.If the thermostat does not work I can replace it with the old one but if I screw up the furnace I’m in trouble.I can put the G back & remove the jumper but I don’t want to pop a fuse etc.The furnace & air are about 10 years old.The wiring in the thermostat I’ll assume is original to the house.The last 2 thermostats have been battery operated since I have been here.The thermostat I currently have (Honeywell) seems to stop once a week.It’s luminated but it’s off.I have changed the batteries twice.When I take the face off & reattach it starts working again so I don’t know if it’s the contacts or the motherboard.Worked fine until about a month ago.

[@JerseyMikeHVAC]

@@Dave-ld3dr Thermostats do not send out a signal for the fan (on G terminal) in heating mode, so the green wire goes unused. Only in cooling mode does the stat send 24v out on G. But it also does so on Y as well., so the jumper wouldn't interfere with heating. nor the missing G wire even without a jumper.

[@Rhenexful]

Very informative 👏🏿 thank for sharing

[@JerseyMikeHVAC]

You're welcome

[@pastortonsils]

Man I could really use you help. I wish there was a place where I can send you pics.

[@mitchblackwood]

after watching a few times i now understand what all the wires do,im just having a tough time wrapping my head around what i can do to install this C adapter for the homeywell T9,i have an okder lennox ac with no Y terminal,my tstat is a 3 wire cooling only so i have R,W and G wires,it tells me in the C adapter manual if i have no Y terminal it wont work for my system,im figuring if i can use another terminal to "fool"it maybe i can get this thing to work,im going to go back and study your video some more thanks

[@JerseyMikeHVAC]

The white wire should be in your Y terminal at the thermostat (originally). That is your Y wire. You don't need W. At the other end of that white wire at the air handler, that white wire will connect directly to another wire that goes straight out to your outside unit. You can try to use that wire as your "Y terminal". The other wire from the outdoor unit is a common wire coming back and should land inside the air handler. Make sure you remember the original wiring because you'll have to put it all back if that doesn't work.

[@Eddy63]

Nicely done ... Thx

[@JerseyMikeHVAC]

Youre most welcome

[@kenvanbuskirk7034]

Thank you solved my issue

[@jimbola77]

thank you brother that is really good stuff to know god bless...

[@marshallstephens7356]

Thanks bro! GREAT VIDEO!!!

[@JerseyMikeHVAC]

Glad you liked it!

[@OHmyn1ck]

Hi Mike, So right now I have a Trane VX95 and a Carrier A/C with only three wires going to the T-stat (wire in the wall has 6 leads) where the red is connected to R terminal , Black to B/C terminal and white to the W1 terminal. I would like to hook up a Honeywell TH6320ZW2003 T6 Pro Series T-stat . The terminals on the furnace panel currently attached are W2-Blue, W-White, R-Red, G-green, B/C-Black (and white A/C wire), Y- yellow (and Red A/C wire). So I'm confused as which I should connect? My thinking is W-W1, B/C to C, R-R, Y-Y. would this be correct? thanks

[@JerseyMikeHVAC]

WHat are you using as your primary source of heat? Furnace or the heat pump? I ask because Honeywell says not to use the W terminal on their stats with heat pump applications. I recently had to disconnect a wire to the W terminal after someone hooked it up there because the heat strips would never shut off. Ran up an $800 electric bill. I had to disconnect that wire, which was also a Carrier heat pump with the Honeywell T6 stat.

[@michaellandolfi2413]

mike I have 2 red wires on my control board one red out of control board going to red or thermostat and a red and yellow wire one the y terminal on my control board I don't know why@@JerseyMikeHVAC

[@JerseyMikeHVAC]

Yellow wire to Y is the call for cooling from the thermostat. Y terminal on control board activates air handler for cooling mode. Red wire off of Y terminal goes to a contactor on the outdoor unit which turns on the compressor and fan motor out there.

[@briancloutier2781]

If you have no C wire running to stat will the wires show 24 when disconnected from the thermostat?

[@JerseyMikeHVAC]

Only the R wire will show voltage. Any other wire can act as a substitute common just for the purpose of getting a reading on the multimeter.

[@briancloutier2781]

@@JerseyMikeHVAC Thanks! Can I get by with now C wire with the sensi stat with batteries? My nest failed on me after 3 years. Kept getting E 74

[@JerseyMikeHVAC]

Yes if it accepts batteries it should work as advertised

[@briancloutier2781]

@@JerseyMikeHVAC Thanks please keep the videos coming they are very helpful!

[@briancloutier2781]

Had a HVAC tech come out yesterday because the board blew two fuses and blower and compressor would not start. He found a shorted wire between stat and furnace. No I have new wires and a C wire!

[@davemarshall9640]

I am in the situation where my control board is spliced in between my Thermostat and AC unit. I am unable to wire up a smart Thermostat because I only have V+ (red) and Vg (white) running from my control board to the Thermostat. How do I bypass the control board completely in order to get all wires down to the thermostat point where I can install a smart thermostat. Unit is Goodman, control board and current thermostat are Carrier. Thanks!

[@JerseyMikeHVAC]

is it just for AC or is there heat involved too?

[@davemarshall9640]

There is heat involved as well

[@JerseyMikeHVAC]

Heat & AC typically requires running new thermostat wire when converting from communicating stats like that. Sometimes 18-3 wire is run from the electronic interface module (EIM) to these com stats where it might be possible to do it without running new wire in heat only or cool only applications. Unless you're very lucky and they ran 18-5 wire to your communicating stat and only used 2 of those wires for V+ and Vg...or the EIM is right next to your thermostat already...

[@davemarshall9640]

Yep they ran 18-5 wire from the EIM to the stat but only connected white and red. At the EIM end on the stat side, white and red are also connected and the rest are terminated/cut and not connected to anything. Then on the other side of the EIM all 5 wires are heading off to the AC unit.

[@JerseyMikeHVAC]

@@davemarshall9640 Perfect. Then you should be able to splice the thermostat wires together color for color at the EIM and just hook up the smart stat at the other end using all 5 wires. Just make note of what color wires are connected to what terminals on the EIM from the unit so that your spliced wires to the stat land on the same terminals they were on at the EIM before you disconnect them.(R from EIM to R on thermostat, W at EIM to W on stat, etc.)

[@andromerful]

Thank you sir very helpful

[@jackg3854]

Great content mate 👍

[@JerseyMikeHVAC]

Thanks 👍

[@johnraylangstonjohnraylang5924]

PS The theme is a 4 wire system. It has white Red green and yellow. It has no other wire that you can hook to . In the unit there a O wire on the broad that other wire come from the side of that main A/C breaker or it called the main contact comes off the side. So do I need either one or can I hook them up to any of the four wires that hooks up to the thermostat.

[@ValuePig]

very helpful, thank you so much!

[@JerseyMikeHVAC]

You're welcome!

[@bduff1992]

Damn no wonder I almost burned to death when I hooked up my new thermostat

[@robbieoden3703]

Please help. I tried installing the Google thermostat only to find out I have an old system. So I decided to reinstall my Wright temp model 6022 thermostat. I only have heating. I have a black red yellow and green wire. I first had the black wire on the Common connection but when I put my thermostat on auto and heat, I could hear it click but My unit did not come on. It will only kick out heat if I turn to the switch to on and heat. It will not work on the Auto button. So I thought maybe the black wire should be installed under B. It only clicks and nothing happens. What am I doing wrong? Please help.

[@JerseyMikeHVAC]

When you say you only have heating, do you mean only the heat works or that this is just a heating system and there is no AC? What kind of system? Forced air heating? Water boiler? Steam boiler? How did you have everything wired other than the black wire? Those two bits of info could help me figure out what the issue is. Normally, G terminal is for the fan. Typically, a green wire. W is for heat, most likely the black wire. Y is for cooling, typically yellow wire is used. Red is used for 24v supply power to the R terminal.

[@robbieoden3703]

@@JerseyMikeHVAC I have forced heat there’s no cooling unit at all. I do not have a white wire. I only have yellow red, green and black.

[@robbieoden3703]

Red is hooked to RH, Green is hooked to G and the yellow wire is hooked to Y. I do not know what to do with the black wire.

[@JerseyMikeHVAC]

@@robbieoden3703 Put it on W. If it's still not working then, take the door off the furnace and you'll see which wire goes on which terminal there. Just repeat the same for the thermostat.

[@robbieoden3703]

@@JerseyMikeHVACthank you

[@lukeleiden197]

Awesome video. What happens when you have three wires on a terminal in a control board? I have three on my c terminal from thermostat, condenser, and humidifier.

[@JerseyMikeHVAC]

A lot of guys will steal 24 volts off of a yellow wire that proves the pressure switch for the 24 volts needed to operate the humidifier solenoid. The common at C just completes that circuit. C from the thermostat completes the circuit needed to charge the stat. C from condenser is to complete the 24v circuit that engages the contactor to turn on the outdoor unit.

[@lukeleiden197]

@@JerseyMikeHVAC that is exactly what they did. So it is fine to have 3 wires at the c terminal and can't hurt the board. Can the just be all connected at the screw or would a wago or wire nut be better? Thanks again.

[@JerseyMikeHVAC]

@lukeleiden197 It won't hurt the board, but I would prefer to use a wire but to tie them together with only one wire on the terminal. Don't like the wago connectors. Electrician friend of mine doesn't advise using them.

[@Dognme]

I have a Honeywell RTH7600 thermostat for my Goodman heat pump, I have 6 wires a Red,Yellow, Brown, Green, Blue, and White my thermostat has Rc/R with a jumper, O/B, Y, G, C, L, E, and Aux any ideas on which wires I can connect to what