Troubleshooting if a Thermostat is BAD: Explained!

This is for testing if a 24-volt thermostat is bad. These are the steps you should take in order to verify that it is the thermostat that is bad and not the wiring or control board. When you make sure that the power is on to the unit, the light (if there is one) is lit inside the HVAC system and nothing happens when you turn the thermostat on then this video is for you. Supervision is needed by a licensed HVACR Tech while performing tasks as Experience and Apprenticeship garners Wisdom and Safety.
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Information in this video is intended for educational purposes only. Any work related to the topics in this video should be performed by licensed technicians or by apprentices under the supervision of licensed technicians. AC Service Tech LLC is not responsible for any possible damages or injuries caused by the use or misuse of any information provided. ▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
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[@acservicetechchannel]

Our Inverter Mini Split Resources: Mini Split Book on Our Website- www.acservicetech.com/mini-split-book Mini Split Paperback on Amazon- amzn.to/3ytHJSs Mini Split Paperback on TruTech Tools- www.trutechtools.com/BooksGuides?aff=8 Mini Split E-Book on Google- play.google.com/store/books/details?id=HN-iEAAAQBAJ Mini Split E-Book on Apple- books.apple.com/us/book/id6445178399 Our Single Speed and Two Speed Air Conditioning Resources: My Paperback and E-Book: www.acservicetech.com/the-book My Paperback: www.amazon.com/shop/acservicetech Read the book reviews on Amazon! Check out our new Articles at www.acservicetech.com/articles Support the Channel by purchasing tools through Tru Tech Tools! Use this link www.trutechtools.com/?Aff=8 Save 8% at checkout using code "acservicetech" My Service and Procedure Book- www.acservicetech.com/the-book 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) UEI DL479 Multimeter with temp sensor amzn.to/2jtsUbJ Magnet Jumpers- amzn.to/2PyKPQZ Alligator Jumpers- amzn.to/2PxqJXn Fieldpiece ST4 Dual Temp Meter amzn.to/2wc1ME3 Fieldpiece Bead K Type Temp Sensor amzn.to/2DBwKfs Fieldpiece Wet Bulb Temp Sensor amzn.to/2RRI7Tw Fieldpiece TC24 Temp Clamp amzn.to/2qHLyjZ Yellow Jacket Refrigerant Gauge Set amzn.to/2aenwTq Refrigerant hoses with valves amzn.to/2aBumVI Yellow Jacket Gauge set & hoses amzn.to/2vLVkV9 Yellow Jacket 4 Port Manifold w Hoses amzn.to/2BkuGIq FieldpieceSMAN360 Digital Manifold Set amzn.to/2BdoaD4 FieldpieceSMAN460 Digital Manifold Set amzn.to/2nB4Fe6 Compact Ball Valve for Refrigerant Hose amzn.to/2KUisW8 QuickDisconnect 90 for refrigerant hose amzn.to/2MMtVcg JB 6 CFM Vacuum Pump amzn.to/2nqbvo8 Appion Blue 3/8" to 1/4" Vacuum Hose amzn.to/2uYlVyc Appion Red 3/8" to 1/4" Vacuum Hose amzn.to/2uYg6Ro Appion Valve Core Removal Tool amzn.to/2uYr8WL Yellow Jacket 1/4" by 1/4" hose amzn.to/2umtcod CPS Vacuum Micron Gauge amzn.to/2v1nM3O Supco Vacuum Micron Gauge amzn.to/2v1JRiA RectorSeal Bubble Gas Leak Detector amzn.to/2ckWACn UEI DL389 Multimeter amzn.to/2xAdaJf Air Acetylene Torch setup amzn.to/2aQalsb 15% Silver Brazing Rods amzn.to/2gVLyLc Nitrogen Regulator amzn.to/2bXdR5f Nitrogen Flow Meter amzn.to/2brvoBg Other tool links can be found in the video description section. Shop through Amazon! Your Purchases through Amazon provide a means for channels such as mine to earn advertising fees from all purchases after clicking through. Prices are the same as normal- www.amazon.com/shop/acservicetech

[@inquisitvem6723]

so before i do anything, i should shut off power to house right? so i dont get electrocuted? then open the panel display? I have a honeywell CT500 that goes blank every so often and now not generating cold air...i have a brand new AC unit too. it has no batteries, so that cant be the problem. i also reset the circuit breakers and the display panel of thermostat still goes blank and then re-appears. it does this every few minutes or so. is it a problem with the wire connection of thermostat? is it loose?

[@acservicetechchannel]

I recommend calling a tech but they would shut the power to the hvac system off and take the tstat face plate off and tighten the connections on both ends, in the thermostat and in the furnace or air handler. After that they will check for 24v to the thermostat and if they have it then it is a bad thermostat. It could also be one of the pins not aligning on the back of the thermostat.

[@inquisitvem6723]

did u power off the thermostat? i see nothing on the panel at the beginning of vid.

[@darrylchappell3440]

How to replace thermostat for boiler heater

[@darrylchappell3440]

How to replace thermostat for boiler heater

[@terencechan7338]

Thank you for saving me a costly service visit! Your suggestion of tapping the R and G wires helped me confirm a bad thermostat! Thank you for taking the time to produce easy to follow instructional videos with detailed explanations that don’t require hvac training to understand!

[@acservicetechchannel]

Glad it helped!

[@sandrarichardson2713]

Hi---It looks like you understood what he said about the red and green wire. Did he say the thermostat is bad if the fan DOES come on when touching the red and green wires together or if the fan DOESN'T come on? Thanks for your help. Jesus bless.

[@terencechan7338]

@@sandrarichardson2713 Hi! He said if the fan turns on when you jump the R and G, then the faceplate/thermostat is bad. Good luck!

[@vetdadcubby4722]

Awesome, I just completed tech school last fall and I'm working for an HVAC contractor! ALWAYS learning!

[@acservicetechchannel]

Great to Hear and in this trade, we all will always be learning! Keep it up because over time you will move up the ladder right past those that stop searching for answers and learning new things! Thanks

[@frustratedmechanic6263]

The best instructor on KZbin... he makes it so easy to understand.

[@acservicetechchannel]

Thank you very much Dwayne Wallace! I am glad you appreciate the video!

[@cozmicmojo2181]

For anyone who's control panel is working and whose unit is fine but doesn't seem to be sending data: If continuity from the screws to the copper is good, look at the AC unit's circuit board and check the fuse(should be purple or amber). I accidentally blew it somehow when moving the thermostat. Easy fix!

[@aureannanicole3477]

Thanks! You saved me so much time. Couldn’t figure out what my problem was!

[@willlove7927]

Thank you I’ve literally watched atleast 2 videos every day and I’ve become a better tech because of you thanks a lot I have to get better at gas furnaces and diagnosing electrical issues

[@acservicetechchannel]

That is awesome to hear Will! Thanks for letting me know!

[@binjagav2053]

My man!!!!!!!! After I changed almost everything in the furnace, not works until I did the test G and R and the thermostat was bad . Now my furnace work like 7/11 store non stop. Thank you so much bro

[@tilnoenecp704]

*Easy to assemble **Fastly.Cool*

[@st.charlesstreet9876]

The explanation and demonstration is so very clear and Very much appreciated, Thank You!

[@erics9213]

Before jumpering the R and G, I would use a multi-meter and check for 24V A/C between the R and C.

[@acservicetechchannel]

Yes, sometimes there is no C to test from though, thanks Eric S!

[@AK99581]

@@acservicetechchannel Was just going to say, that method wouldn't do you any good for a thermostat with batteries..

[@AlphaGolf1]

I had a call where the AH was running but the condenser was not. I had no voltage between C and Y at the control board outside or the AH. Pulled out the Tstat and jumped between R and Y and the system came on. Tstat was bad.

[@cassondrad2280]

Awesome. Girl Power. You helped me figure it out. I GOT HEAT. I so refused to call service man. I knew if air conditioner worked and I tested just like you showed to boot the fan, then I knew it wasn't the furnace. I have where red wire could go either to RC or RH, it was at RC so I hooked red to RH and I got heat. Thank you

[@GomezTavo]

I have RC and RH. How did you test the thermostat?

[@AK99581]

Even though you now have heat, that's not really the proper way to do that. You shouldn't have to constantly switch your live wire over every time you want to switch between heating and cooling. If you only have one red wire coming in from furnace control board, it should be hooked into the RH terminal, while a separate jumper wire should be connected between RH and RC.

[@armenlock9619]

So clearly explained and helpful. Thank you so much. Lets me know if I should call our utility that installed the energy saving thermostat or if it's time to call an AC tech without wasting his time or mine.

[@acservicetechchannel]

That is great to hear, thanks

[@MrRasgabriel]

Thank you so much for helping me bring heat back to my home for my family!

[@robertnieves5848]

Thank you, I was able to fix my AC problems using this video, thanks for taking the time

[@acservicetechchannel]

Awesome to hear, thanks!

[@mostlikelywedoitservices6926]

Another way I have done it. I used the pins on the back of the thermostat battery operated type. Call for blower the pins should ohm out. Same thing for calling for heat. Make sure you are connecting to the correct pins because they are not marked you have to reference how the pins plug into the back plate.

[@Robginski]

If the heating works and ONLY the A/C won't work, what is the most likely culprit? The thermostats display is fine, as is heat. Do you have a video to diagnose A/C only? I think the fan is fine since heating is working.

[@rabdhall05]

Thermostatic expansion valve(TXV hvac)? I've learned that when they fail, that the heat can still work; they are designed to fail that way(generally speaking), so you'll still have heat if it were to happen in extreme cold season. Might not be of any help to you; just thought I'd suggest in case you're still in need, being it came to mind when I read your comment.

[@libertyfox7486]

Good Stuff, My pro TH8000 on Cool or fan, the heater turns on. This test should expose issue that I believe is 25 yr thermostat

[@joshr9358]

Great video! It is to the point and easy to understand. Thanks!

[@acservicetechchannel]

Thanks Josh!

[@stephenzoll4597]

What’s wrong when the thermostat works on fan only ? When put on auto the ac and the heat don’t work. It does nothing, no sounds or anything

[@HsingSun]

Thank you very much for your video. My system was keeping running when both inside and setting temperatures are matched, what is caused the problem inside the air-handler, need help?

[@Volusiaev]

If you need heat in an emergency, would you have to connect the three wires (r g w) altogether? Or will just jumping the r & w work?

[@acservicedaytona386portora3]

Again another great video...

[@acservicetechchannel]

Thanks Robert!

[@themaz6802]

First than everything thanks for the video well explained .. My friend I put the thermostat at 83 this morning and it shutoff all the sistem now it won't start. and nothing in the screen I put new batterys and nothing.

[@acservicetechchannel]

Did you check to see if you have 24v on the indoor unit from r to c? It is possible the power at the indoor unit is off or fuse is blown, thanks

[@themaz6802]

Yes I do the thermostat was the problem. I buy another one of the same i just put the new in it problem solved..thank you very much for your help.🙏🙏👍👍

[@Lemurian.Quartz]

Is there a follow up video of what to do if this doesn’t work?.. I recently got a new condo.. I installed a “smart thermostat” by EcoBee. It worked fine for a few months but then suddenly stopped. I’ve flipped all breakers, I tried the things in this video.. what is weird is that since it is smart, it will send me notifications when it turns on about the temperature. I will be at work, and out of nowhere (nobody lives in my condo than myself and my cat) it will turn on for like 20 minutes and then go off again..

[@human-sn7lk]

I have a 2 wire Carrier edge thermostat- any way to test that?

[@DrSolo-qb1ze]

Hello Craig. I was working in the field and ran across a thermostat that the voltage on the R and Y was 16 volts, it also showed 16 volts in the air handler and 16 volts in the condenser. Testing the Red with green, and Red with white both registered 27 volts. What could be causing the voltage drop? The contactor does not show any voltage on the coils, but when testing the coil for ohm it shows 12.8 ohm and it also has continuity. The contactor is not sucking in at all. What could be the problem? Thanks for your input.

[@koolmodee4542]

Thanks - just tested mine and it was, indeed, the thermostat - fixed and back to cool for $25.

[@acservicetechchannel]

Awesome, thanks!

[@Dave-um1hl]

Hi. The screen on my thermostat is blank. I replaced batteries, nothing. A couple days was back on. Now blank again…but, if I press the temperature up, it comes on (not the screen, the furnace). Also, if I turn fan on it comes on. Any ideas 💡. Thanks so much.

[@geojor]

very practical video, thank you ...

[@acservicetechchannel]

Thanks Pei Broker!

[@Markvdubr32]

If I’m jumping power to check the heating operation I always add the fan into the jump beacause I don’t want any thermal overloads to burn out by turning the heater on without the fan running

[@justinsanders6276]

What causes the ac to keep running when thermostat temp reaches but it’ll cut off at night when outside temp cools down?

[@victorrojas7071]

For residential home with local thermostat. Possibly a schedule for the cooling on the thermostat.. 1 yr later and no one could comment their best guess. Comments are greatly welcome

[@victorrojas7071]

The ac with cold air keeps running after reached setpoint? If just fan is running blowing normal return space temp air, then blower probably has a schedule. Or the contacts themselves are bad in the thermostat and the unit shuts down late at night due to low pressure/ low limit with cold outside air. Then resets the next day

[@kelleewilkerson6822]

Sure is hot in here this summer but im going to miss these low electric bills once i do get the ac fixed one day. Big difference in 250+ per month and 30-40 per month!

[@stillmatic03]

Last night was only night 3 for me.. running the fan on myself wasn’t so bad even though it was 86 in here (Florida)

[@Eddy63]

Awesome video. Good teaching tool ...please keep up the good work ...

[@acservicetechchannel]

Thank you very much!

[@jaelin38]

acservicetech I have a White Rodgers thermostat that is not working right. I have no control of the temp settings. I touch up or down arrow it goes to 90 by itself. Heat kicks on and run for maybe 2-3 minutes and drop to 62 and eventually cuts off. Is tstat bad? Please help me

[@titanicsauce2152]

I learned alot. Thank-you!

[@barryward192]

Do have to turn power off for to see if fan come in

[@andrewskerbitz1358]

Thank you! Info helped diagnose the thermostat.

[@acservicetechchannel]

Glad to help Andrew!

[@robertomurri1278]

I have a question if you don't mind answering it. I have a Honeywell thermostat, and it would blink like the thermostat was about to turn off completely. So I switched the coin cell battery and when I put the front plate back on to the back part mounted on the wall. I waited for it turn back on, and I put the cool air to auto and on 65. The fan never came on tho, and even when I bring it down to the lowest temp. It would still say "Cool On", but nothing. What could it be? Should I do what you did in the video? I did turn the breaker switch to Off, and then back On and it worked for a min then it shut off. Smh.

[@christophermoore9897]

So if you jump the 24v wire to the g wire and it turns on (thermostat is set to auto not fan), that means the thermostat is bad ?

[@dubbya57]

The only way to get my heater to kick on is to change the fan selector from AUTO to ON. Then when the desired temp is reached I change it back. But then it wont kick on again when the temp drops. Should I just replace the thermostat?

[@antoinewong5539]

At 4:48 you said if the fan not come on do you mean fan blower or condenser fan?

[@acservicetechchannel]

Thanks for the question. I am referring to the blower motor only turning on. Thanks

[@miketreat]

Great video. Thanks for the help

[@acservicetechchannel]

Thanks Mike!

[@mikellandrum6673]

Any idea what would cause the blower motor to blow harder once I removed the jumper wire to diagnose the thermostat. My blower kept blowing for about 20 seconds after I pulled the jumper wire and it blew harder than it did when thermostat was working

[@lexus3577]

When you say fan, are you referring to air handler fan or compressor fan? My AC is not getting 24V at contactor to turn on compressor and compressor fan but air handler fan is working. I'm getting 24V b/w R and Y, R and G, R and W on thermostat. When thermostat calls for cool, G and Y goes from open to shorted (connected). So the thermostat is working fine, correct?

[@carlitosducoing8507]

So where is the thermostat located ?? Mine rums for 8mns cool..but fan stays on forever

[@aron352352]

The fan? The blower or condensor fan?

[@nld-bl5ct]

My Lennox Air Handler CBA 27 fan will not come on on circulationg "ON' setting since it was installed 3 years ago. Just running AC from my attic. Would like to circulate the fan all the time. I have even changed out the thermostat. Any thoughts?

[@draugami]

My thermostat is set for 60 degrees at 3 am. The thermostat still runs at 68. Is the thermostat unrepairable? How long does a thermostat last? 10 years?

[@ricter591]

Thanks Helps a lot.

[@acservicetechchannel]

Glad it helped

[@CtTrammell]

How do I reprogram this unit ?

[@56rmax]

Do you have a video on testing the thermostat wiring for shorts and or breaks?

[@acservicetechchannel]

Yes I do believe. Look through the "acservicetech Thermostat Troubleshooting Playlist" for the videos there, thanks

[@xhacu9625]

For some reason. On my Goodman single stage furnace. I jump r with the A/C and it works. But my heat and fan don’t. Any reasons on why?

[@ebiedog]

My ac wasn't blowing cold so I had a tech recharge the refrigerant. It helped but now, a week later, whenever I switch the thermostat from ON to Auto, the fan doesn't blow. Any suggestions?

[@chingonyayo]

Thanks for the awesome video bud!!

[@acservicetechchannel]

Glad to help chingonyayo!

[@mikewhite7608]

thanks this video helped us at our home

[@acservicetechchannel]

Thanks Mike!

[@jerrodwilliams6789]

also If the reversing valve solenoid was beginning to short out would it fry the defrost board or the thermostat? its a lennox 13hpx-030-13

[@chickedwin7194]

Believe or not sir, you are the best

[@acservicetechchannel]

Ha ha, thank you very much Chick. I am glad you enjoy the videos!

[@chickedwin7194]

@@acservicetechchannel Sir pls i need your help. How do you check sub cooling on a mini split with no service valve on the liquid line. Thanks in advice

[@acservicetechchannel]

So if the minisplit is a vrf then we the manufacturer usually doesn't give us any charging guidelines for it. What I have found though is that in cooling mode when the temp was above 70 degrees, many systems operate at 0-5 degrees of superheat on the full speed emergency cool call. The only reason that they function like that is so the saturated state is arger and they use the accumulator to protect the compressor. In normal units, low superheat would be a big problem for the compressor. The manufacturers just want us to use the total weight method for checking the charge which is a complete recovery, pressure test, find and fix the leak, pressure test again, vacuum, break the vacuum with the total amount of refrigerant that the system says it needs per the rating plate plus additional line set length, thanks

[@chickedwin7194]

@@acservicetechchannel great

[@mindofmayhem.]

My heat- off-cool button is stuck. It will go the left towards cool, center, but won't go to the right (heat) when pushed. Any ideas? Mine is the opposite way from the one in the video.

[@jerrodwilliams6789]

Have you encountered a lot of problems with nest thermostats? Mine just quit powering the O wire so the reversing valve stays in heat mode with the thermostat set on cooling.

[@acservicetechchannel]

Hey Jerrod, did you check for 24v volts by reading the o and the c at the outdoor defrost board with the thermostat on cooling? Thanks for your service!

[@jerrodwilliams6789]

Yes I did and 24v was not present at O. it’s confirmed it’s the nest thermostat. I plugged the one from downstairs into the upstairs unit and the unit started operating properly. if the reversing valve solenoid was beginning to short would it burn out the thermostat or the defrost board? Thanks

[@acservicetechchannel]

Technically, it should just blow the 3amp fuse at the indoor unit before hurting any control board or tstat. It would be likely the thermostat than the board but with the power off, unplug the compressor and take an amp draw on the reversing valve by wrapping the low voltage wire around the amp clamp 5 times to read the low amperage and divide by 5 if you thought that was the issue, thanks

[@bradh6185]

I have a blank screen on my thermostat. Outside unit, so no drain pan. Thermostat wired to house so batteries not needed. However, the screen comes on when I install batteries. But nothing else happens. But the two snowflake icons flash. This is a 3-year-old PRO1 t701 thermostat with a Comfortmaker unit. What would you recommend I check? It's a hot Saturday night in Texas and having a heat stroke in the past, I don't handle heat well.

[@acservicetechchannel]

You would need to check the 3 or 5 amp fuse in the outdoor unit after turning the power off. test from r to c with a multimeter for 24v, thanks!

[@luisausay2462]

thank you very much SR. you are the man!!!

[@acservicetechchannel]

I am glad you enjoyed the video Luis!

[@ferminrosa9620]

Thanks very useful ❤️🙏

[@contraptor10221]

i put a new thermostat this summer honeywell RTH111 it work well , i try to turn on the heater today i hear the gas came on but the fan is not working or do i need to wait a little bit and the fan came on

[@acservicetechchannel]

If the furnace is trying to turn the heat on then it is receiving the signal from the thermostat. It is past that and in the furnace. It sounds like maybe with the power off the capacitor should be tested or at least a tech will start there if the blower motor is not coming on. This one would test with the power off. ---- kzbin.info/www/bejne/nJ3FhqeCgsqGhbM

[@DaBuick]

I’m having intermittent thermostat issues. Going to replace it tomorrow am when the store opens. I appreciate the video, it confirmed what I had done.

[@acservicetechchannel]

Thanks for letting me know!

[@thewanderingadobo]

I did this test and it did turn on the fan. Is bad thermostat also be the reason why i got limit circuit lockout? Thanks in advance.

[@acservicetechchannel]

No a limit circuit lockout would be from one of the sensors or from a component within the sequence of operation only. A thermostat is just a signal voltage going to the control board terminals. Check out this video on the sequence of operation----kzbin.info/www/bejne/q3zWg6OPotyfpK8

[@vufirst]

So to manually turn on the cool/AC, I would need to turn on the fan and the compressor. And to turn the heat on, I would need to turn on the fan and the heater on. From another video, I would say to turn on the cool AC on manually, I would short Red, Yellow, and Green wires. Moreover, to turn on the heater on manually, I would short the Red, White and Green wires.....Am I right?

[@acservicetechchannel]

Heat needs to go through its 7 step sequence of operation which includes the fan turning on. Heat does not need g jumped. Thanks for your comment!

[@mml1224]

good vid...but wait do i have turn the unit off at the circuit breaker or near the unit BEFORE i jump the red/green wire? i would think the unit should be on, so then the fan can come on if does happen to trip? please help

[@acservicetechchannel]

The unit would be on while jumping from r to g at the thermostat. You can turn the unit off for safety while taking the cover off initially and then turn back on for testing, thanks!

[@mml1224]

​@@acservicetechchannel anything i can do to test the TSTAT wo doing that? My TSTAT, delayed when dropping the temp from 78 (all day on at 78) to 75, cool word just blinked for 15 minutes, NO cool blower came on!.... then turned on after 15min delay.... 2nd time it happened, i shut off the unit for 30 secs. and turned it back on, and tried dropping the temp, and it delayed for a bit 5 mins or so but the cool fan came one.....does this help on what it could be??? Blower or TSTAT?

[@acservicetechchannel]

@@mml1224 If this is an ac only then you can remove the thermostat face and jump from r to y or r to y and g. If the air conditioning turns on and runs with no problem it is not your control board. Make sure to not turn the compressor off and then back on in under 4 minutes. The refrigerant pressures need a chance to equalize.

[@mml1224]

@@acservicetechchannel Thanks, but if the the a/c blower comes on after jumping r to g or r to y, then its the t stat? Or what else can it be, I heard a blower motor capacitator?

[@vetdadcubby4722]

To the point and direct, great job keeping it simple!

[@acservicetechchannel]

Thank you very much, glad you enjoyed it! Here is the playlist for thermostats if interested----kzbin.info/aero/PLxnHR5_D2ojzDfU1IjPpzdhi_mUGe3F7W

[@KindCountsDeb3773]

My Honeywell TH5000 works, turns on ,etc. BUT it is wildly inaccurate. Displays wrong house temps and will come on in AC when temp reads 77 IN house and No way is the house temp 77. SO, I get very cold in my house on A/C. I'm Not technical, thought maybe I could reset/reboot it, etc, but not sure. Any advice??? thanks

[@acservicetechchannel]

Sounds like you may have batteries that need to be changed in the thermostat or that the thermostat needs to be replaced, thanks!

[@ianinoc2663]

connecting directly of red to yellow means no indoor fan will be running, only compressor.. how about red to white, does it mean only heating and no indoor fan? t.y. :)

[@PhyllisBennettNana]

Having problems with the air conditioning sometimes when it is on there is no cool air coming out..had a wellness ck up in june..guys said outside unit was fine just needed cleaning.. But once in awhile it seems the spark doesnt start the cool air..we turn it off for 10 mins..the on and it will start..could it be its not firing up correctly?

[@PhyllisBennettNana]

Also inside temp will say 82° and will not go any lower..til we turn it off for 10 mins then restart.we.always change batteries first a check fusebox..fusebox not hot..

[@chriscavender9482]

My furnace no longer works in auto mode but does in manual on mode. Fan will run and furnace will fire and heat. Could the thermostat be the problem if it switches manually? Thanks

[@acservicetechchannel]

Are you talking about the manual fan on and fan auto. If so then it sounds like the furnace is not calling for the fan to turn on after heating up. Do you have one of these and is the furnace older. If so, this may be bad. It is a fan limit control. --- kzbin.info/www/bejne/oqPSh6KYoa5kpsk

[@shawnavery6048]

I got rth5100b is there a video to show me how to hock it up in my RV

[@joycebreen2986]

Everything works but I can't get my number above 37.The room temp says 27

[@carybodiford4730]

Very helpful,,,thanks

[@carlosking8720]

Do i need to connect 3 wires together to check my heater? I mean the red is power and the fan wire plus heater wire? or just 2 wires red and the heater wire? Thanks

[@acservicetechchannel]

Just two wires R and W as the furnace will know when to turn the fan on by itself. Thanks

[@Marjie73]

My furnace won’t shut off how do I test to see if it’s a bad thermostat? The only wires are a white and red

[@acservicetechchannel]

You can take the face of the thermostat off and see if the furnace shuts off. Look up "acservicetech thermostat playlist" for all the thermostat troubleshooting videos, thanks

[@mssullivan4067]

I just noticed the blue wire is hooked in the "y" yellow spot. Been working for yrs until now and i just noticed. Is that common? The problem I'm having right now is my thermostat says cool when it's turned on heat, but heat is coming out. The set temperature isn't correct though. I have no idea what the heat is actually on. Once it gets warmer enough, i just turn it off or it will continue running bc the temperatures never match up. Possible problems?

[@acservicetechchannel]

That sounds like you should have the thermostat replaced. The previous tech may not have followed the normal color code. You can verify the colors by looking at the indoor unit control board terminal letters thanks

[@mssullivan4067]

@@acservicetechchannel Thank you. I removed the batteries and cleaned the inside. I think I will still eventually have to switch the thermostat though because I noticed the numbers won't show up every now and then. I will check the panel and colors though.

[@robira1313]

Any idea why my heat pump won't shut off after reaching the desired thermostat setting? It does turn off if I turn off the whole unit at the thermostat. Just not when it's supposed to when it reaches the desired temp. Any ideas on that?

[@acservicetechchannel]

Sounds like a bad thermostat, thanks

[@tomdonald2495]

ok now it makes sense

[@acservicetechchannel]

Thanks Tom!

[@seshachary5580]

very educative thank you. regards

[@acservicetechchannel]

Thanks Sesha!

[@acservicetechchannel]

Sesha Chary, I am very appreciative that you chose to Support the ongoing work of AC SERVICE TECH through Patreon! Feel Free to email me any questions you may have at [e-mail] also let me know what questions you would like answered or shown in the quarterly Insider video, thanks!

[@corinnemoring500]

I have a question the hurricane I just had knocked my power out for a day and when the power came back on my a/c unit didn't... What's wrong with it?

[@acservicetechchannel]

Is the thermostat power on? Is the indoor fan not running or is it just the outdoor that isn't running? Basically, did the breaker turn off, did a fuse blow inside the unit or a fuse blow at the disconnect at the outdoor unit? I was just looking for more info, thanks

[@katanatac]

My furnace fan wont turn off by the thermostat even when switched to the off position, what do you think the problem might be?

[@n9neduece]

katanatac bad T stat

[@katanatac]

Sorry, not really up with the talk of the trade, what is a "T stat"?

[@acservicetechchannel]

It could be the thermostat, thermostat wires, or the relay on the board. Have you seen the acservicetech Thermostat Troubleshooting playlist and the videos at the top?- kzbin.info/www/bejne/pnepYnagZ7uherM

[@acservicetechchannel]

n9neduece was saying thermostat in short. Thanks!

[@katanatac]

Now my transformer burned up, it had smoke coming off of it.

[@barryward192]

I have a t701 thermostat it show rc and rh connect with a jumper do I jump with green and rc

[@christyinthecarolinas]

I have this same thermostat and I've changed with fresh batteries and the display is all wonky. It is only showing partial numbers. Any ideas?

[@acservicetechchannel]

It sounds like the thermostat is bad or is not getting the right ac voltage on the r terminals.

[@jimmyung3212]

Thank you!!!

[@acservicetechchannel]

Thanks jimmy ung!

[@vjnblnum2303]

Thank you sir

[@acservicetechchannel]

Glad to help Vjn!

[@vetdadcubby4722]

Thank you, looking forward to it!

[@hitemup85]

My outside fan is on but my unit in the house won’t turn on what could it be

[@acservicetechchannel]

That could be a bad indoor fan motor or just a bad capacitor, thanks

[@jttaylor2970]

How do you turn off your unit if the thermostat isn't working?

[@AJservicetechAZ]

JT Taylor pul the disconnect or shut it off at the breaker?

[@jasonsanchez8006]

What if your unit makes a clicking sound when jumping 24v to your fan motor.

[@acservicetechchannel]

24v to what fan motor? Do you mean to the g terminal?

[@jasonsanchez8006]

Single phase. Goes to a gas furnace

[@jasonsanchez8006]

Its basic 2 wire t stat. (Low voltage)

[@momx2o534]

What if the metal jumper broke? Any way to wire it or do I need a new thermostat?

[@acservicetechchannel]

You can make a new jumper out of 18 gauge wire. We bend it and then flatten it with a hammer on a thick piece of metal or we use a jumper left over from another thermostat, thanks

[@momx2o534]

acservicetech thanks so much!!

[@sandrarichardson2713]

I'm a little timid about even asking this question....if the face plate of the thermostat is off and you are jumping the wires outside of the backing plate..how are you turning off and on anything? I'm lost a little (or a lot---lol) on this. My AC is blowing but not cool. Trying to troubleshoot a little to see what I could try to replace but hate to replace parts that are not bad. Anyone with a suggestion....I welcome it. Thanks much. Jesus bless.

[@s.e.d6021]

my thermostat has steadily been dropping it now says 50 degrees and ive set it on 71.. needless to say its stuffy..i changed the batteries and it went up to 51...somebody able to advise me at ALL?

[@pollydecesere6883]

is there a way to turn my thermostat up i have to put a cold cloth on it to get more heat.

[@acservicetechchannel]

Here are some reasons depending if you have digital or a mechanical thermostat. It sounds like the thermostat is not reading the temperature correctly. If this is the case and you have a digital thermostat which is non adjustable then you would either replace it or just set the temp up higher. The thermostat thinks it is hotter than what it is so you would just have to set the temp up higher. For instance if you had to set it at 77 to keep the house at 72, it may turn on at 70 and shut off at 72 possibly but read as if it is 77. If you have a mechanical thermostat then you could turn the power off to the furnace and adjust the heat anticipator dial under the thermostat face plate to a shorter cycling rate. Move the dial in the opposite direction of longer cycle by about a 1/4" or .05amp and then turn the furnace back on and test it out. It should turn on sooner and have a lower temp difference between when it turns on and turns off. Then turn the furnace back on and see how much it helps. If you need to adjust again just do the same procedure until it turns on and off again at comfortable points. I hope this answered your question! Thanks

[@darlazy1]

Thermostat unit screen was damaged and could only read if the fan was on auto or circ. Changing the fan option did not do anything so I tried this. When I used pliers to jump the red n green wire a small spark happened and then nothing happened. When I place the unit back on, there is no power and the word fan that was legible before is no longer there. What can I do now?

[@acservicetechchannel]

The 3 amp or 5 amp fuse is likely blown but not because of jumping r to g because that happens any time the thermostat calls the fan to turn on. You should replace the thermostat and replace the 24v fuse in the indoor unit, thanks

[@darlazy1]

AC Service Tech LLC what caused the power to the unit to go out if not jumping r to g then? It was working fine prior to jumping. Also is there a specific 24v fuse I need to buy or are they all pretty much the same and fit with any indoor unit? Lastly where in the indoor unit is the fuse located? My indoor unit is located in the attic if that helps. Thanks

[@acservicetechchannel]

It could have if there was already if there was a problem short from g to the c wire but if you were to test any 24v thermostat, they connect r to g for fan because 24v comes from the indoor unit and connects to g at the tstat and comes back to the indoor unit to power the g terminal on the board or g wire going to a relay. It could be a spade or bottle fuse but turn the power off to the unit and check it if you are a technician. This channel is for technicians in the field and those at HVACR school. If you don't have electrical experience then I would call a tech in to replace the tstat, check your wiring and take care of your fuse or any other problems. They would be able to figure problems out with a multimeter, thanks

[@susidowns5288]

I don't have a problem with the fan coming on. I can't get it to turn off without pulling out relay. Help. I am guessing I need a new thermostat?

[@acservicetechchannel]

Turn the power off then pull the face plate off of the thermostat, turn the power back on and see if the fan turns on, If it does, then turn the power off, take the thermostat face plate off, see if it turns on. If it does then, after that turn the power off and disconnect the fan wire from the furnace or air handler, then turn it on again and see if the fan runs. This will tell you if the problem is in the tstat or wire, thanks

[@kevindelk]

I jumped the red and green and fan came on. But the red and white did nothing, no heat.

[@acservicetechchannel]

If you jump from r to w at the control board of the unit with the door switch closed and the heat turns on then you have a bad thermostat or thermostat wire, thanks!

[@bdmappliancerepairllc4436]

What if your furnace doesn't stop when it gets to desired temperature just keeps running

[@acservicetechchannel]

That sounds like a bad thermostat or bad thermostat wires. If it shuts off after disconnecting the thermostat face then the thermostat is the problem, thanks

[@allenbrown7791]

I have a hunter programmable an I was wanting to know what the switches on the back of the panel are it says non/hphp sw3 witch one should it be on I have gas

[@acservicetechchannel]

It would be non heat pump if you just have an ac with gas furnace, thanks