Top 12 Problems/Mistakes when Installing or Replacing Thermostats! HVAC Tips!

[@acservicetechchannel]

Tool List- www.amazon.com/shop/acservicetech Support- www.patreon.com/acservicetech For those that are looking for the tools used in the videos: (Linked Below) Here is a link to the self drilling white wall anchors- amzn.to/2xRvoJh Here is a link to the Pro 3000 24v Thermostat used in the video- amzn.to/2keuUbs Here is a link to the Heat Pump 24v Thermostat with Aux and E Controls- amzn.to/2x8ISBE Here is the link for the Irwin Wire Stripper/Cutter/Crimper amzn.to/2dGTj2V Here is the link to the 3amp fuse 25 pack- amzn.to/2y2zkFC Here is the link to the 5amp fuse 25 pack- amzn.to/2z4SyKD Here is a link to the thermostat 3/32 screwdriver -- amzn.to/2hxt7uK Here is a link to the Fieldpiece SC640 Multimeter- amzn.to/2x8k4Kb Here is a link to the Stanley 6 in 1 screwdriver- amzn.to/2x7NuaZ Other tool links can be found in the video description section. ACSERVICETECH is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon. All of the ACSERVICETECH Playlists- kzbin.info/door/OZR-1IqsAer9wzlvFgb4mAplaylists?view_as=public If you want to support the ACSERVICETECH Channel and receive more HVAC content, check out www.Patreon.com/acservicetech

[@drock1383]

acservicetech add 1 more to the blue wire to b terminal-blown fuse. Is it ok to use a 5a fuse instead of a 3a? No big deal to go and get a 3a fuse, just wondering. Thanks big time. I was wondering if i was gonna have heat tonight.

[@acservicetechchannel]

Always use the same as the system calls for, thanks!

[@dansummers4980]

Thank you sir fixed my heat

[@AH-tx1nj]

Through watching this video and looking at my thermostat I installed this spring I corrected my Jumper issue. Thanks for the help. The heater is on and working. My wife is happy im the man of the house and you just saved me $ from having to call a hvac guy. Thank you.

[@michaels48]

7 years after your video was published and people like me are just now learning about the damn FUSE!!! Replaced my blown fuse and everything started working as normal. Thank you for the video!

[@cooleyray]

this for sure saved me. I crossed the red and grey by accident I had no idea why my furnace wouldn't kick on and then this video mentioned a fuse. $6 later and my air is back on. Thank you!

[@kgwoodward1]

This video helped me immensely. I moved my thermostat from one room to another, and was absolutely certain I had rewired it correctly, but the system wasn't still working. I couldn't for the life me figure out why. Turned out to be problem #6 in your video - I blew the furnace fuse by accident. I never would have figured that out without your video, and/or a service call from local HVAC repairman. You saved my money and time. Thank you.

[@daethule]

I would've never even known to check the blown fuse, and yours is the only video I found which mentions it. Fuse replaced and thermostat actually wired correctly according to the manual (which it helps to read), heat now works. Thank you!

[@dcolasono4582]

Just one quick tip to possibly add: Make sure when you tighten down on the terminal screw for each wire that your making contact with the copper wire and not the insulation.

[@rubenapalma794]

You people are amazing!!!! I been watching so many videos and none of those give me the right information until find yours. there is no way to go wrong with such explanation, clear and to the point knowing each and every mistakes that could happened I do not have the right words to express my gratitude. Thank you very much!!!!

[@acservicetechchannel]

Thank you very much Ruben!

[@acservicetechchannel]

If you want to support the ACSERVICETECH Channel and receive more HVAC content, check out www.Patreon.com/acservicetech All of the ACSERVICETECH Playlists- kzbin.info/door/OZR-1IqsAer9wzlvFgb4mAplaylists?view_as=public

[@Matt_224]

@1:29, that's when my brain clicked and I realized what I did. Thank you. Your video save me hundreds to have a HVAC guy come out on Memorial Day to replace a fuse that my dumba$$ blew by hooking up the blue wire. Thank you.

[@sammarshall7463]

Found out the hard way, too. B-is for Black NOT Blue. Go figure- the Blue wire goes to the C terminal. Is there a real reason B goes the C, instead of just using a Black wire as the Common???

[@sammarshall7463]

Gotta find the furnace circuit board to replace the 3amp fuse. In the morning, good night!!!

[@ReneeDooley]

You're a life saver. I knew the wiring was correct but didn't consider the fuse. Thank you so much!!

[@dadsworkshopbykipplabrie7982]

You win you made the best video and best explanation for us HVAC dummies. Thank you thank you thank you! My thermostat rabbit hole has ended.

[@andy2310ify]

You saved me 125 dollar visit from an HVAC technician, someone had wired my thermostat wrong and was able to fix it with this! Thank you so much

[@acservicetechchannel]

Thanks Andy!

[@andy2310ify]

acservicetech my white wire is going into the AUX port should there be another white white that runs from AUx into Emergency heat?

[@acservicetechchannel]

You can if you want emergency heat to turn on by itself without the outdoor heat pump, thanks

[@ll-bp6lj]

That's good!

[@jonathandill3557]

I had reinstalled my original thermostat because I was afraid that the new one wasn't working properly, but this video gave me the confidence to open up the air handler (after turning off the separate breakers at the air handler!) take pictures of the terminals and wiring diagrams and try again. It turned out that the changeover timeout was just longer than I expected (missed the "waiting for equipment" message before) and the new thermostat has been working great ever since.

[@protegosolutions5765]

one of the top thermostat videos on youtube, thanks for your information

[@acservicetechchannel]

Thanks protego!

[@stumpy7777]

I'm not the smartest tool in the shed but this just made me a little smarter and I was able to fix my thermostat thank you

[@isbesoooasian]

as someone thats hates working on electrical wires, i was able to troubleshoot my problem. much thanks!

[@jbroheretoday]

Watched a bunch. Yours is the best. Wish I had found it first. Thank you.

[@davidguberman4780]

Problem #8 is often the most overlooked and most frustrating problem to cure. Thanks so much for posting pointing this one out!!

[@acservicetechchannel]

Thanks David!

[@KingOfErehwon]

@@acservicetechchannel Consider using a small, plumbing vice grip to hold the wires as you switch the backplates.

[@meatypunk]

Thanks so much for this video! I had blown the 3 amp fuse and was going crazy trying to figure out the issue. Saved us from a cold night tonight.

[@davidharris9451]

AC Service Tech, thank you very much!!! Your guidance and teaching has been a tremendous help.

[@acservicetechchannel]

Glad to help David!

[@Tito_hvac]

Thank you. This is the best explanation I’ve watched about thermostat wiring

[@acservicetechchannel]

Wow, thanks!

[@kdouglass7131]

A/C guy came out today and told me my thermostat was bad. He could replace it for 345.00. I said no and found your video. I think I can replace it myself and save about 200.00. Thanks for such a great video.

[@acservicetechchannel]

Thanks!

[@petesingh292]

Why people charging too much money just to replace stat? I charge only $185 here in Northern Ca

[@MilesKnowsBetter]

Just replaced my thermostat over the winter furnace was working fine it stated to get hot and my AC compressor would spin but furnace would not blow. Went over all my wiring issues they were right after watching your video it was set to electric and heat pump I never saw that option during install. Thanks so much for your video its back to working great keep up the good work ...

[@acservicetechchannel]

Awesome, thanks

[@erpgolfer]

Man, great call on the fuses. Never would have known 5 amp fuses were inside the furnace? I have dual, and they both blew. Actually, all of your tips are great. Wish I would have watched before I started, but I'm now up & running. Thank you!!

[@acservicetechchannel]

Thanks erpgolfer!

[@nicolek5747]

I think I may have finally figured out the issue with our thermostat after years of dealing with intermittent issues with the heater powering on. I'm going to try tightening the cables right now. Thank you!

[@joyroc885]

One of the better videos out there. Only thing I might add is that on older systems like mine blue goes to o. So make sure you note it before removing it.

[@Chataleki]

Hello, I’m so grateful that you have taken the time and knowledge of explaining which wires “should” go where and why. Your direction is very helpful. I just moved into a condo and did need to call a technician at $78. to determine my problem The thermostat was that not working was probably an original as my home is now 20yrs old. He was such a kind and honest man telling me he’d have to charge $485. to charge the thermostat. I don’t have that kind of money and my homeowners warranty I always carry was a day away from kicking in, so he was so great at pulling the cover off of my thermo (something I thought would break it straight away, because I honestly had no idea that’s how to even work or change it. ** back to my problem **... I followed directions, put the stickers on where the wires had been. Everything seemed like clockwork and because we’re going down to freezing temps at nights so I was thrilled to get my heat working. I don’t want the programable option on this Honeywell model I chose so have been using the override method. When I’m hot, I know that and if I’m cold I’ll adjust it, so no need to have a set schedule to keep me comfortable. Ok...finally my problem 🙄,i discovered today...because it actually got warm today, that I wanted to cool my home just a few degrees and that’s what I’ve been trying to figure out the last 6 hours. What did I not do correctly. I have a hydroponic system so I followed the setup listed in the thermostat direction. When I switched it over to cool, I can’t get it to kick on. Your explanation of the wires might be helpful only obviously I’d like some backup now because my A/C isn’t kicking in. I’m 60 and often can repair easy things and today with Utube it’s almost foolproof, and that word of foolproof hasn’t been on my side with this thermo. And now with your tutorial I might have a chance, However, with my current problem and question obviously “I’m” not foolproof. I’ll try to check and rewire where my mistake may have happened and hopefully I haven’t ruined anything. Wish me luck. Sending me a little advice would be extremely wonderful if you’re reading this blog, and my problem is probably one you’ve encountered. Thank you again for your tutorial on thermostat education.

[@acservicetechchannel]

There may be a dip switch on the tstat on the back side or you may have put the wire that was in y into the new tstat at y1 instead of y/y2, thanks

[@Chataleki]

Hi there! Thank you for that. You may not believe what happened but I’ll tell you anyway. I was ready to punch myself when I’m holding this top part of the thermo in my hand and was just staring at with a whole bunch of anxiety when I noticed that the very end pin is bent and that’s the port where the mm

[@olay650]

Good tips. Perfect content, not too long, not too short. Great video. Thank you.

[@acservicetechchannel]

Thanks Olay B!

[@UremicFrost]

Thank you so much! 4 wire thermostat. AC worked but not heat. I ran a jumper from RC to R and now my father-in-law thinks I'm HVAC certified 🤣🤣 Blessings

[@virginia347]

Very easy to understand! Thanks so much!

[@acservicetechchannel]

You're very welcome!

[@arulmoviemakers]

Great Tips! Thank you! My replacement thermostat was expecting 'C' connection, but my existing thermostat did not have C, but there was wire available, but not connected. I opened the HAVC and connecting the 'C' wire, and connected the new thremostat- but it was not working - I though i blew the fuse. After seeing your video, I realized it is the auto-shutoff safety switch!! once i put the panel back on it started working again. Thank you very much!

[@sgtrollinski8090]

Thanks, just switched from 4 wire to 5 wire, luckily the C wire was there just not being used. My heat wasn’t working because I had to switch my red wire from RC to R instead, and put a jumper between the 2

[@domingoruiz2904]

Thx. for excellent info. 👍

[@acservicetechchannel]

Glad it was helpful!

[@billytrant9512]

Thank you ! Just fix my heat . Jumper wire fell off. Must have happened when Painters removed the thermostat

[@acservicetechchannel]

Thanks Billy!

[@karld3155]

Great video, well spoken and easy to understand and learn from. Couldn't have found this video at a better time

[@acservicetechchannel]

Awesome, thanks Karl!

[@Gary-ts6dh]

9:48 - FIVE MINUTE DELAY! This one bit me hard. Several years ago, I ran around for the full five minutes with my voltmeter checking to see if I turned the correct breaker on, checking for integrity of the disconnect fuses, and making sure I had 24v to my new battery-operated TStat. (Thanks for the heads-up; but, I would have put this one first. I bet I'm not the only idiot out there that doesn't read the installation manual.) When my HVAC/R instructor turned me loose on a system in the lab last night to connect gauges and calculate superheat, he didn't tell me about the delay (he just handed me a set of gauges and an IR thermometer and said go to it.)

[@bookworm81151]

Thank you. This was a really helpful. and saved me almost 200 dollars.

[@acservicetechchannel]

Thanks Bob!

[@josevaldez3648]

Ikr

[@jaredstone9487]

How did you save $?

[@MajesticL.]

Had I seen this earlier I wouldn't have lost those $200 😆 Damn! Oh well. Maybe next time.

[@forexchallenge7379]

Good video bro thank u for sharing

[@acservicetechchannel]

Thanks for watching

[@jacksmail7725]

Excellent video. TThank you..

[@acservicetechchannel]

Glad you liked it!

[@KennethArnoldarnoldservice]

Thanks so much for making this excellent video! I am sure that you will save many people lots of headaches and problems when trying to install thermostats! Thanks, AC Service Tech!

[@acservicetechchannel]

This is Kenneth from Arnolds Service Company Inc right? Thank you for what you do as well! I still remember my wood shop teacher and the impact that he made on me. May the Lord Bless You and Your Family! If you need anything, let me know! Thanks!

[@KennethArnoldarnoldservice]

Yes, This is Kenneth from Arnold's Service Company. You and your videos have been such a blessing to me and my customers! Thank you so very much for all your blessings, and for making all of the great and awesome videos! God bless you and your family today and always!

[@acservicetechchannel]

Thanks a lot Kenneth! Have you checked this video out on the thermocouple and the combination gas valve- kzbin.info/www/bejne/hpqmnpmNZteHiLs and this one on the water heater thermopile?- kzbin.info/www/bejne/iHK2c62BlL15aM0

[@randywoodruff9989]

Great Video and explanations !!! Thanks

[@acservicetechchannel]

Glad it was helpful!

[@lomex_1417]

highly recommend this purchase!

[@rymakazlova9629]

Thank you very much, it was a really helpful video!

[@acservicetechchannel]

Glad to hear that!

[@Comedianmsanita]

This was VERY HELPFUL THANK YOU

[@acservicetechchannel]

I'm so glad!

[@allamericanconex]

Nice video. New batteries. All works but No Back Light. Two wire, heat only Thank you

[@johncote2776]

Great Video! Another problem is someone used hex head screws to attach the thermostat on the wall. Hex head screws stick out too far and don't allow good contact between the thermostat base and the thermostat. Always important to use screws that are flush with the base.

[@acservicetechchannel]

That would do it, thanks Blue Collar!

[@andrewarzoian4266]

Outstanding video, thank you. When I initially installed my new thermostat I indeed connected the blue wire to "b". I switched it on but got nothing. No heat etc. Most likely I blew the furnace fuse?

[@redskinsfan5227]

Great video

[@acservicetechchannel]

Glad you enjoyed it

[@Jessiesuain]

Thanks man I learned a lot by the same thermostat model

[@TelematicsLegend]

Thank you for showing me where the fuses are, saved my mom $200.

[@wheeltwavel]

Thank you thank you for your video. It's 1:30am freezing outside and I decided to install a similar stat. Shorted the thing out on the c terminal! Board on the furnace went dead no lights or anything only blower fan capability I nearly sh%t myself I took off the circuit board cause I saw a spark out of the corner of my eye but when I inspected it I didn't see the fuse. I also wired it all wrong as the instructions were incomprehensible to me. Watched this video and now the heat is on!

[@mbrick]

Great video. You are very thorough and I learn something in each of your videos. Thanks.

[@acservicetechchannel]

thanks MBrickner87!

[@The-H-inADHD]

Wanted to thank you for all the great help and videos you make and post!!

[@acservicetechchannel]

Thanks GhostReaperX!

[@The-H-inADHD]

You can't tell from my youtube lol, but I'm going to school for HVAC at the moment so I watch your videos and we have even watched some in class.

[@acservicetechchannel]

I got ya, awesome to hear! Out of curiosity, which videos did they have you watching in class?

[@The-H-inADHD]

We watched refrigeration cycle and one on superheat and subcooling.

[@acservicetechchannel]

Are you at a college, technical high school adult course, or trade school? I am always concerned at how much people pay for some options.

[@mirooovuujjj7918]

Awesome video,thank you for sharing 👍🏻

[@AZ_sunshine]

appreciate all of your videos (& book), has helped a lot with my original problem. Question . .should i replace tstat wire from wall to attic terminal due to ecobee tstat burning up? Few details: . I lost power to thermostat & boards after installing an Ecobee5 tstat, which brought me to your videos. My system did not have a fuse. I replaced the transformer, added a piggy back 3A fuse to the secondary side, still no luck, so I replaced the timer board and ignition control module and finally power back at tstat, boards etc. Once the ecobee was powered up the screen said 'delayed start-up" then read 100 degrees, then 110, then 120! I had to use an oven mitt to remove it. The ecobee contacts melted on the back on one side. Now back to no power. Before moving forward would I need to replace the tstat wiring since the insulation appears to be slightly melted on the copper wiring? thanks for your thoughts if you have time.

[@lancerudy9934]

Ac service tech thank you for all the great videos!

[@acservicetechchannel]

Thanks a lot Lance! Also the paperback just was released today at acservicetech.com thanks!

[@Kimmykat2700]

I wish you could help me here in Kentucky! I've had the worst luck with my HVAC since the condenser and compressor was replaced! They said it was my thermostat...2 years later I've replaced the entire system as of last week and it's still cycling off and coming right back on 90 seconds later. My power usage has tripled since the first install on the original system. 300x more wattage usuage than prior year or month, and I can see the usuage by the day, wk month, yr, etc and it aligns perfectly with the first install inside the air handler.They've came to my house at least 25 times with 10 techs. My original system was a Rheem and I think they've done something to make it drain voltage but NO ONE can figure it out. I'm currently sitting here after having surgery, watching videos trying to figure it out while it runs non stop wondering how I'm going to pay the power bill! It's set to 74 but feels like it's actually 70. It runs all night long and if internal temp is registering 74 as it's set on, it still cycles on without the temp rising to 75. I can bump it up to 75 hoping it'll cycle off and instead it comes on. It's as if the temp is wrong or it's pushing electric heat somewhere. Idk but I wish I could fix it😭

[@nurfetalic205]

Craig you always sailing. with the wind nice presentation thank you buddy.

[@acservicetechchannel]

Thanks Nurfet Alic!

[@williamflynn5647]

Hello Great video makes it easy to understand what is happening with a t-stat and the HVAC equipment

[@acservicetechchannel]

Thanks William!

[@daningram3143]

Thanks for your videos! I’ve installed a new digital thermostat. No matter how long I run the air conditioner the thermostat will not change temperature. The air blowing is 58 degrees. Any idea why the thermostat will not pickup the house temperature? Thank you!

[@jeremyp6516]

Thanks for the video!!! The little jumper fell out of the R/Rc terminals and I had no clue that was the issue until I came across this video.

[@acservicetechchannel]

Thanks Jeremy!

[@rodgarcia6563]

I have a garage heater with W G C and R. It works fine with a basic 2 wire thermostate. I put in a Honeywell programmable unit with no C. I hooked up the R to R with a jumper to RC, the W to W and used the G for independent fan operation. I can turn the fan on but after setting the thermostate it is calling for heat but the flashing led in the heater stays slow, it flashes faster when heat is called for. Triple checked connections, good clean new wires, new batteries. Everything looks like it should work but no heat. Put the old two wire unit back on and heat comes on. I am at a loss. The thermostate is a RTH221B Honeywell Home programmable thermostate and the furnace is a 50000 Btu Heatstar. Also I did make sure to switch to Gas/oil operation on the thermostat. Any ideas? Thanks in advance and thanks for the video

[@douglasmccray2305]

I have fumes coming from my vents in my HVAC system could it be from the thermostat wiring?

[@karagregory69]

Good Info. I thought you looked at OLD thermostat, take photo of wires before disconnecting wires, and match letters up to terminal letter on new. I never realized G=Green, Y=Yellow etc. Just what ever wire is connected to Y on old, put it to the Y on new regardless of wire color. If green was on Y on old, put Green on Y on new one. It always worked when I replaced thermostats using this method. Some have a switch in the back for Gas or electric heat.

[@acservicetechchannel]

Yes always replace new thermostat with wiring like the old one. That is just the thermostat color code that technicians should follow for installations of new thermostats, thanks!

[@paulhong732]

Thank you ❤❤

[@warrior59paul11]

Alot of people are switching their analog for digital thermostats in their RV. The typical Rv 30amps service has a 12 volt (7.5) Red wire that is connected to the analog stat. That wire is no longer used to power the stat if batteries are used in the stat. This is my understading as well as the high and low fan speeds which are brown and blue wires connected together ,which only gives the high speed fan setting (toogle switch installed gives low speed option). Could you advise on this and address this for campers? My camper has red, green, white, blue, yellow and brown wires. Thanks

[@Ms._Carriage]

#3 on the switch on the back. For an all-in-one system, with using the jumper, furnace/ac, would u still switch it to "gas or oil" even if its an electrical furnace..?

[@gupttura2766]

Thanks for the video...very good explanation for learners. I bought a Honeywell T5 WiFi thermostat. After opening my existing honeywell, I realized there is no wire in 'C' terminal. I believe I would need C wire to supply power to new thermostat. I checked the board on the furnace and it has a RED wire in C terminal...not sure where this red wire going? WHat options do I have to install wifi thermostat? In my thermostat, I have wire in Rc (red), Y (blue), W (black), G (green) just 4 wires in total.

[@acservicetechchannel]

You need to run an additional wire or possibly do away with the g wire and use it for a common. You would need to test it though in heat and cooling to make sure it still turned the blower on. If your indoor unit does not have a control board then you cant try that. Also some boards do need 24v to g, others dont need it.

[@gupttura2766]

well I hired someone to do the job because I also have HRV system. My board on the furnace have too many wires to figure it out. Thanks for your suggestions. We use G wire for C. It is working ok.

[@noel888]

i read that i could remove the programmable section and just leave the wiring in tact. If i get the same thermostat and just replace the old program one, would that wiring be good enough? Also how do i detect the right fuse from my panel when i am alone?

[@tptm100]

Question: If you were to test a furnace control board that had a blown fuse with a your meter probes where the fuse goes would the meter or the transformer get damaged because the cause of the short was still present when you repower the board?

[@dmorgan28]

Thanks for your expertise.

[@acservicetechchannel]

Glad to help!

[@patriciacs85]

Any tips for wiring a new thermostat when you have just a boiler for radiators. And only 2 wires coming out of the wall. I tried RH and W/E on the Sensi thermastat and the boiler just turned on

[@jianbinhuang]

Great video, just wanna say thank you.

[@Darignobullseye]

THANK YOU!! I needed help and you Greatly helped me! Thank you!

[@ionu4535]

This is what makes KZbin good; few gold nuggets are out there, but find most are POS. Would have paid $$ to see this video before I replaced my thermo; if I had, would not have blown an attic fuse that cost me $75 on a service call.

[@acservicetechchannel]

Thanks Ion U and sorry to hear!

[@brenth2858]

Excellent help! Thank you!

[@acservicetechchannel]

Thanks Brent!

[@teabee44]

Can a 2 wire furnace run a t-stat without batteries? It would need a hot (r), common (c) and heat (w) right?

[@Blackdog4818]

Would the "jumper" already be there in an AC/Heat Tempstar system? I just got a new furnace about 2 years ago, and the guy said something about getting a new thermostat because mine is an old mercury slider, not digital. If I only have 4 wires coming out, I'd have to jumper R and Rc? I've realized it's about 4 degrees off and would like to replace it. Thought it was going to be easy. Thanks for the video because I would never have know the difference between the 2 Honeywell digital model numbers. There is no battery in my current thermostat.

[@andrewsims7182]

I'm fishing the KZbin community for help. My HVAC system was staying on towards the end of the winter last year. As far as I could tell the both the indoor and outdoor unit ran all the time. Also as far as I could tell the heat strips did not come on. The pipe copper line set felt warm, but the temperature stayed at 70 degrees where I had the thermostat set, it just never would shut off unless I switched it off on the Tstat... Since it was getting warmer anyways, I limped through on the wood heat leaving the system off. This summer the AC side worked flawlessly. I am however ready to troubleshoot to see what is going on with the heat side. Any advice would be appreciated! Great video! Thanks.

[@andygalindo8978]

Thank you just love this . You make it easy.

[@acservicetechchannel]

Thanks Andy!

[@ericenriquez9155]

have you ever had a short on the control board ? popping the 5 amp fuse.

[@MRCOOL8377]

Just saved me a lot of trouble and got my family some heat tonight. Great video, great explanation, made my problem solving simple!

[@acservicetechchannel]

Thanks MRCOOL8377!

[@ll-bp6lj]

Awesome!

[@SonicBoomC98]

Seems like it would be best to take a picture of the old one before starting the change out

[@liaf525]

So just to make sure I’m understanding, the C wire provides power to the thermostat so that it works? I could have a thermostat without batteries?

[@ThunderStruck15]

That is correct. The problem comes in an instance like mine where there is no C wire coming from the cluster of wires in the wall. Because the Yahoo the wired the trailer I live in for some reason thought batteries were the bestest =[ that would have to rewire from in the wall to get a hard powered thermostat instead of a battery-powered thermostat.

[@TheJohndeere466]

Actually the c wire is the common wire or a neutral. So the r wire is the 24 volt hot wire but the c wire is the neutral that allows a completed circuit back to the furnace. Without the c wire you would just have a 24 volt hot coming from the furnace and when the thermostat called for heat it would close the contact and send the 24 volt back through the w wire to signal the furnace to turn on. the furnace will work fine like this but the thermostat itself has no neutral to complete the circuit so it can power itself if it has wifi or is a programmable thermostat or if it has a lighted screen. Some thermostats have batteries for this purpose but most with wifi wont work without the c wire.

[@kennethmccann6402]

Also, I put caulking in a hole because thermostat goes haywire by exterior doors or windows opening and closing is bring cold draft for heating start up too soon which was interior is already too warm.

[@peterv1806]

Outstanding info - very well described - thank you!

[@acservicetechchannel]

Thanks Peter!

[@PJMDValley]

Good video ..... most common problem is people don't do proper research.

[@lightsobrite]

Ty for your last speedy reply....much appreciated!!!!😊

[@acservicetechchannel]

That really sounds like a bad thermostat, thanks

[@kasmotkariin7920]

Thanks for your video, it's really helpful. My question though is do i leave my R wire in the thermostat side connected and connect my 24v external adapter to C and Rc? I'm trying to hook a T5 Honeywell and I have a 4 wire system (heat and cool) in place. Thanks.

[@acservicetechchannel]

You would keep the R and Rc connected.

[@tiberio1352]

​@@acservicetechchannel Hello !! Thanks for your video. Please, I have also a 4 wire system coming from the wall. R, W, Light Blue, Green . In the OLD t'stat light blue was connected to Yellow in the thermostat. I connected the same way to the NEW thermostat, R and Rc with a jumper. Is that oK? I thank you in advance.

[@stacyveith4297]

Love the music in the background!!

[@networth8754]

My existing system is Gas Furnace and single AC unit. My existing thermostat has C,G,W,Y and R (no jumper). The new Thermostat has the choice of RC or RH with a jumper. (no R). Question: Which terminal do I place the existing "R" wire to? RC or RH? Do I leave the jumper in or remove?

[@jerryhicks1242]

Does the "set" temperature allow the thermostat to change from the heat mode to cool?

[@danielmorgan827]

What if you only have a white and black wire in the wall. Can still use the thermostat type used in this video?

[@malloryhartt7695]

I currently have a 5 wire programable thermostat. I want to replace it with a new updated thermostat. My question is can I go from a 5 wire programable thermostat to a T2 non-programable thermostat?

[@eazy69ful]

Having trouble with my thermostat with the old one it had power now when I change to the new one no power have all the wires right I took a snapshot

[@louismartinez7772]

Great Video. The best I've seen on this subject. I am trying to install a smart Honeywell unit, my problem is per Honeywell I need 5 wires. I found three in the wall that were not used for my older unit. A white one, black one and a ground wire. Where do I put theses? Is one my C wire?

[@craigzilla100]

Great work and thanks for sharing! Question for anyone who can answer.. my mother in law had some guy install a new Nest thermostat in her home, ac/ gas furnace combo, but now the heat doesn't work. The AC works and the fun runs, but no heat comes out. Problem is, I don't know how the old thermostat was wired.. the next currently has Red to R, white to W, yellow to Y1 and green to G. This all seems right to me, but obviously there's an issue. I appreciate any help!

[@acservicetechchannel]

You might need to go into the settings to make sure it is set up for the correct type system, thanks

[@khaitran3709]

How can I find the furance in my condo, I don't know where is at so I can check the wiring and check that 5amp fuse also, cause my thermostat does not allow me to go past 50 degree?

[@billfriedman5219]

In a two story home where is the proper location to mount a thermostat. Up stairs close to the return air or downstairs not close to a window?