HVAC Electrical Troubleshooting! How to Find a Low Voltage Short!

[@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 Fieldpiece SC640 Multimeter- amzn.to/2x8k4Kb Here is a link to the Fieldpiece SC660 Wireless Multimeter- amzn.to/2gWDUhc Here is the link for the Irwin Wire Stripper/Cutter/Crimper- amzn.to/2dGTj2V Here is the Link to the "Lil Popper" 24v 3amp Breaker- amzn.to/2xWcVrR 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 Stanley 6 in 1 screwdriver- amzn.to/2x7NuaZ Here is a link to the thermostat 3/32 screwdriver - amzn.to/2hxt7uK 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

[@danieldummett3731]

Honestly brother your videos have helped me to be increase my knowledge so much over the past year that I have been watching. Thank you so much and continue to do the great work that you do.

[@acservicetechchannel]

Thank you very much Daniel!

[@MrJwinne]

I’ve been following this channel for over a year now . All this guy does is make you next level . How anyone could thumbs down his tutorials is mind blowing . He’s better than any HVAC teacher out there and providing nothing but knowledge for free . That equals putting money in your pockets . Just had to put that out there . Merry Christmas !

[@acservicetechchannel]

May the Lord Bless You Joseph! Merry Christmas!

[@MrJwinne]

acservicetech likewise my friend .

[@rubin2200]

Yeah I love acservicetech. His videos help me understand what I am being taught at school a lot better

[@acservicetechchannel]

Thank you very much Rubin!

[@MrJwinne]

Rubin Hands down the best on KZbin . His teaching skills are impeccable. If I had a teacher like this when I first started out . I would’ve been next level very quickly .

[@franciscoflores2862]

I hope you're and your Family are showered with blessings for all the work you put into sharing your knowledge. You're one great dude!!!

[@acservicetechchannel]

I appreciate that very much Francisco!

[@dbru2650]

You have used a great example by pointing out the condenser control wire. I have found that a large percentage of the shorts in a control system is in the control wire from the board to the condenser. Homeowners and Landscapers (and in some cases chewing rodents) cause havoc with the control wire near the condenser with their weed whackers. Great videos. I went to HVAC training in 1978, I'm an old-timer now, but you are the best instructor I've come across. Thanks for helping out the lesser experienced techs, your videos are great!

[@WinstonFlorent]

On another video I noticed you said open line. It's all good. Thanks for sharing all your knowledge for free.

[@acservicetechchannel]

You bet!

[@aaronshoyt]

What if it didn't blow my fuse, but instead in blew my transformer? Also great video.. Best hvac channel on KZbin.

[@ahinnaynoble6938]

Wow! I've learned more from your videos than the school i attended.

[@powerpooch2000]

Great video very informative. I enjoy the way you present it with all the components within view on a table. Unlike the other videos I've watched particularly the ones on the field with the noisy motors blaring on the background and the terrible camera angles and bad lighting. they should all be done like this. Kudos

[@acservicetechchannel]

Thank you very much powerpooch2000!

[@frankcorrieri]

Thanks for your help buddy. I was able to track down my short (something the techs said they couldn't do) after watching this video. It was the yellow one going from the board to the outside unit. Instead of running new wire, I just used the brown one that wasn't in use. Many heating cycles later and no blown 3 amp fuse

[@acservicetechchannel]

Glad it helped Frank!

[@tonyneil9660]

glad i found this video, very clear and simple

[@edwinjewell5359]

You Really are Great at your craft Thanks for the help you give. Stay Well and keep up the Great Videos.

[@acservicetechchannel]

Thank you very much!

[@antoniosantiago2770]

Anything under 8 ohms on a contactor will blow that fuse also. I’ve had it happened. Thanks for your videos. Big fan.

[@acservicetechchannel]

Thanks Antonio!

[@capitolrefrigerationheatin7501]

on the coil of contactor?

[@antoniosantiago2770]

Capitol Refrigeration,Heating,and Cooling on a 24 volt coil yes. Ohms law.

[@antoniosantiago2770]

Capitol Refrigeration,Heating,and Cooling That would be a three amp fuse. Odd call but if you ever get it you’ll see what I mean.

[@capitolrefrigerationheatin7501]

makes sense, i never thought of it that way,thanks for that info!!!!

[@romarues1]

Great job explaining. Can't be any more clear. LOVE YOUR VIDEOS MAN.

[@acservicetechchannel]

Thanks Roma!

[@gilbertopatino2616]

Thank you very much for another great video. May God bless you and keep you.

[@acservicetechchannel]

May the Lord Bless you too Gilberto!

[@tonyolivera7994]

your videos are my second school...Thanks dude

[@acservicetechchannel]

Thanks Antonio!

[@tedatondo8793]

Great teacher. Mexicans in here

[@geojor]

valuable information on a common problem, thank you ...

[@acservicetechchannel]

Thanks pei broker!

[@gilbertopatino2616]

Thank you for another great video.may God bless you.

[@acservicetechchannel]

May the Lord Bless your endeavors!

[@nurfetalic205]

Nice video and good explanation. Very straightforward.

[@acservicetechchannel]

Thanks Nurfet!

[@ddcws1]

Thanks Craig! Video cleared some things up.

[@acservicetechchannel]

Hey David, thanks and I hope it did. Let me know if you have any other questions on this or anything else. I hope you don't mind, I put your name in the description for asking the question, thanks!

[@luiselizalde6757]

Excellent explanation Thanks valuable gift you have, Have a wonderful days.

[@acservicetechchannel]

Glad to help Luis!

[@bryantylerservices]

Awesome.. Instructional video... Appreciate contractors/ instructors as yourself! Bryan Tyler refrigeration

[@acservicetechchannel]

Thanks a lot!

[@juiceybananas5489]

Good info on those god-dam low volt short , thank you.

[@michaelcostello6991]

At 3:31 you talk about the 2 red wires that go to the safety switches.Its not clear what they do. Do they cut power to the thermostat if any of the safety switches open ? A schematic of what your doing would have been a great bebefit to help newbies to follow and reduce basic questions like this one . Thanks for video. Michael

[@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

[@whitesheatingairappliancer7101]

Great video, thank you.

[@acservicetechchannel]

Thanks Ron!

[@rickdebacker100]

I love your system mock-up, but I think OL stands for open line. Just my understanding. It may in fact be 'over limit' but what exactly is over what limit? I need to know these things! Thanks again. Keep it up!

[@acservicetechchannel]

open line, open limit, over the limit of resistance that the multimeter can measure.

[@5822huron]

Now this is good

[@acservicetechchannel]

Thanks!

[@knighthvac4876]

Great video , Alot less intimidating laid out like that ! Thanks for posting

[@acservicetechchannel]

Thanks Knight Hvac!

[@joservargas32]

Excellent videos. I wish my boss could explain things as well as you do.

[@acservicetechchannel]

I am glad you are enjoying the videos!

[@drifter436]

Thanks for this lesson. Can you tell me a good study guide for the epa 608 universal test. Thanks.

[@acservicetechchannel]

Are you taking this through escoinst.com, epatest.com, local supplier, or another curriculum source? Each test will be slightly different and different strategies used unfortunately.

[@drifter436]

A friend that teaches at the local tech college is going to give me the test when i am ready. I was looking on line and found a lot of info, but was trying to find a good book.

[@acservicetechchannel]

The test questions are different through each testing agency presently. That was why I was asking which one he uses, thanks

[@drifter436]

I see. I will have to get with him and find out. Thanks so much for all the videos you put out. I have learned a ton from them and thanks for all the info on the test.

[@noahpuckett4851]

Great video learned a lot thank you very much.

[@acservicetechchannel]

Thanks Noah!

[@04DynaGlyde]

Thank You for these videos! I work in HVAC as a helper and I'm trying to learn use of multimeter. For detecting/trouble shoot any type of trouble such as electic motor problems, capacitors, transformers and contactors. I want to learn and have a clearing understanding of testing volts, amps, hertz, and contiuity etc. This is all very confusing, and where to start and or comprehend. I just don't know what to look for. Please help????????????

[@acservicetechchannel]

Hey Carl, yes it can be confusing and it certainly takes time to understand what you are reading and why. If you are looking for videos maybe look up "acservicetech multimeter" or "acservicetech psc blower motor" "acservicetech capacitor". The multimeter ones will give you testing of functions and reading voltage, blower motors will give resistance values and capacitors will give mfd readings. Thanks and continue on your journey!

[@michaelcostello6991]

You say at 8:43 you need to always disconnect the wires from the control board so we dont measure the resistance of the resistors in the board. Can you explain what these resistors are for. Why does the Y wires not go straight to the condensor. Thanks Michael

[@airmechanical7163]

Excellent video.

[@acservicetechchannel]

Thanks Air Mechanical!

[@befriendmywater142]

Very informative, Thank you. I have a question, my transformer was burned when I turned on the AC. I installed a new transformer and it was burned again a few minutes after I turned on the AC. Which part of the system should I check besides the contactor to find the low voltage short.

[@acservicetechchannel]

You should connect a 3 amp spade fuse along with the two spade connectors on the 24v power of the transformer. This way the transformer won't blow like that. Disconnect the wiring going to the contactor and at the indoor unit and see if the two wires have a resistance reading. That would be bad as it should read 0.L. Also check the yellow wire against the common wire from the indoor unit to the tstat. Make sure that they are disconnected first, thanks

[@earnestthompson6763]

They also have a tool call short pro tool works a little better than the lil popper and safer because it will identify a short below 3 amps

[@checks_3749]

It would be great for you to teach me I’m totally lost and these videos help a great deal. Your awesome 👌🏼

[@acservicetechchannel]

I am glad that they are helping, thanks Brooklyn Droner!

[@donnierobertson3088]

Great job

[@acservicetechchannel]

Thanks Donnie!

[@jimbola77]

thank's partner for sharing super video!!! God Bless.

[@acservicetechchannel]

Thanks Jimbola77, Happy Sunday!

[@martinm7912]

Great video! Can you do a video on twinned furnaces please

[@mondoalvarez2486]

Hey AC Service tech always have liked your video and long time subscriber was wondering could you do some videos on some package units like you have with your residential units. Ones with two compressors, multiple fans, ecnomizers, ect.... I try to search for videos and they just don't compare! Thanks !!

[@acservicetechchannel]

Thanks Armando, I will keep that in mind as I get a chance, thanks!

[@DW-vl2wi]

Try this on for size: 5v at R. 27v at AHU bus. 5-10v at a junction between T-stat and AHU. Both safety switches are connected and have 27v passing over them and connected to R from T-stat and G from condenser. Also, the T-stat has old 7 wire setup, no extra wire, just old wires to swap around. What you gonna do? This what I'm going to do. I'm going to remove some form of heat, just to get 24v at the T-stat. Inform the h/o of what I did, and get another tech out to replace the T-stat wire, and confirm wiring at AHU is satisfactory. Residential work can really blow sometimes, ahahah.

[@acservicetechchannel]

Ha nice. I am having a hard time understanding where you were taking your measurements from exactly but thanks!

[@WinstonFlorent]

Excellent explanation of the workings of HVAC system, however I need to correct you one thing, you keep referring to the OL on the multi meter as over limit, the correct term is open line. Hope you accept it as constructive criticism.

[@acservicetechchannel]

It can mean many things, open line, open limit, over limit and two others. In some videos I say open line and techs will say it means something else. The bottom line is the resistance is so high that it cannot be measured and the circuit is open. No prob at all and thanks!

[@ОляП-д4х]

good video!

[@babaolowo35]

Thanks 👍

[@mostlikelywedoitservices6926]

Good Stuff

[@SombraLocs]

Great video! Is there a big difference between the SC640 and the SC660?

[@acservicetechchannel]

The SC660 is wireless so the SMAN460 will detect the temp readings, thanks!

[@michaelcostello6991]

Why do they ground the common at the gas valve and not at the transformer ?

[@andrewthacker114]

Good helpful clip

[@acservicetechchannel]

Thanks Andrew!

[@steelod1528]

Hey craig i bought the 3 amp lil popper and the male terminals on it did not fit into the female fuse connectors on a lennox unit i had done did you have to change the size of the male connectors in order to get them to fit

[@tankttehctiw8776]

Excellent

[@acservicetechchannel]

Thanks tank!

[@joshisaacks1526]

I've been confused lately looking for low voltage shorts because r (or 24v hot) will have continuity to ground I believe through the coil on transformer. I have a problem remembering or knowing what resistance values are normal for things like that

[@davidmayhall6567]

Simple fix with inspection and a Dvm. Look for cut wires outside by weedeaters look for wires melted or bad splices no tape on connections no romex connector on furnace and wires shorting to ground

[@acservicetechchannel]

Ha ha yeah those are nice and the easy ones to find for sure, thanks!

[@PBS-nm1uu]

lost on this one where is the molex plug wired to ??

[@neilvestervictor180]

just want to ask what text book for refridgeration basic and higher level

[@INLANDEMPIREKING]

Having an issue on a package unit system worked 1 month after installation. 2nd stage cooling is causing unit to shut down on high limit. Changed the board and working for 2 weeks now again out on high limit. I have it now wired for 1 stage rn so customer has cooling the compressor 2nd stage is good ohms ars good. New ductwork 4 ton I have 14 ,12, 12, and 10 inch duct off plenum 20 inch return

[@cooldude2245]

I’m not getting 24 volts at contactor. I think the blower motor at the handler is weak too

[@JL-fq8yy]

acservicetech thanks for posting this video. I have an issue. When I do the first check behind the 12 pin connector to ground / the metal frame the meter reads 0.00. And during the last time the furnace was running it smelled like something was burning. I traced all the roll out switches and wires with no visible fraying or grounding noticed. I'm able to turn on the power, and I can switch on the fan, but it attempts to turn it (fan) on but it doesn't actually turn on the blower. I paid $60 for a tech to tell me the circuit board was bad, so I paid $100 dollars and replaced the circuit board. Still no luck, if I turn on the call for heat at the thermostat the fuze blows.What could be the issue? I've tried your colored wire checks and continue to see "OL". I think I might have burned the thermostat but it appears fine, no charring or smelling of burnt connections?

[@acservicetechchannel]

Hey J L, Here is the Link to the "Lil Popper" 24v 3amp Breaker- amzn.to/2xWcVrR Here is the link to the 3amp fuse 25 pack- amzn.to/2y2zkFC -- what you could do is start disconnecting an item at a time. You would need extra fuses or the lil popper if you can't seem to find it with resistance readings. Start by taking the tstat face off and jumping r to w for heat and see if there is a problem, if there is then it is not the tstat face. Next disconnect the wires going to the board and jump r to w there to try to turn heat on. If it works then the problem was in your therm wire or tstat. If it doesn't then the problem is in front of that at the board. You could also trun the power off and disconnect the transformer leads and test the voltage coming off of the transformer which should be 24-29volts, let me know how you made out, and if you are still having an issue. If you want to support the channel patreon.com/acservicetech thanks

[@titusjordan5886]

how is the transformer in circuit with the fuse, for the fuse to protect the transformer

[@acservicetechchannel]

Yes the fuse is there to protect the transformer, thanks!

[@antoniosantiago2770]

If you check r and c and the control board do you get OL OR do you read resistance from the transformer incorporated in the board.

[@acservicetechchannel]

Any time you take a resistance reading, you must disconnect the component or wiring from anything that has a control board. You should check the wires disconnected from the board, thanks

[@joshsimpson7073]

I have burnt two transformers in a row. Both burnt only on the primary side. Can a short to ground on the secondary side cause the primary side to burn up?

[@erickandrade1921]

Yes. It fucked me up too cause I was taught in school a low voltage short was gonna short the secondary but i worked on a blew up transformer on one of my dad house and it was a shorted wire going to the low pressure switch was runbing and eventually exposed and shorted on the suction line and I looked at the back of the transformer anx fhe primary was black so yes

[@luishernandez5394]

I have a package unit that keeps blowing the fuse on one of the transformers it keeps tripping after turning it on for 10 seconds. But I disconnected the g wire at the low voltage terminal block and it didn’t trip anymore but also the 2 condensor fan motors don’t come on . It is a 208/ 3 phase unit but the condensor fan motors are single phase 208/230 with a 10 mfd capacitor. Anyways I had also found to bad fuses one one of the legs of power at the disconnect and at the unit on a terminal block before the power enters the unit. What do you think is going on? Low voltage short

[@chrisackerman7305]

AC Service Tech LLC just gotta say Ive been watching your videos all day and theyre very informative. This video is the exact problem im having. We have the fan running and when we turn it to COOL the fuse blows. Everytime. I feel I have narrowed it down to something on the AC unit itself. I replaced the 3 wire running from board to unit because it looked old and dried out. Wasnt the fix. Still blew the fuse. I then unplugged the 3 wires from the AC unit and turned on COOL and the fuse DID NOT blow. Wires plugged into AC unit...fuse blows...wires unplugged from AC unit fuse doesnt blow. So now I can use some help from here. Im thinking contactor or capacitor. Any and all advice would be greatly appreciated. Thanks ahead of time.

[@acservicetechchannel]

Check the resistance reading of the 24v coil that the two wires connect to on the contactor. Make sure those two wires are disconnected with the power off first. If it is 0 ohms then yes the coil is shorted together, if it is .6 or higher then it is correct. Also make sure the coil does not have resistance reading with ground, thanks

[@chrisackerman7305]

AC Service Tech LLC alright I did it exactly how you did in the video. I tested the contactor and it read 1.4 ohms. Tested the wires and it read OL.

[@chrisackerman7305]

So I had already bought a capacitor and contactor. Just installed them and boom the AC turned on. Not really sure which one was bad but it's working now. Again thanks for all the videos and knowledge, you've been super helpful.

[@acservicetechchannel]

Awesome, thanks Chris!

[@officerkrupke4966]

Chris, your contactor coil should read between 15 to 20 ohms. 1.4 ohms means that the coil wire is shorted internally, lets say for example a coil made up of ten feet of wire is now essentially one foot of wire, and from ohms law, less resistance with the same voltage applied, means increased current or amps. Fuse blows. Capacitor would have no influence on low voltage ckt.As part of springtime maint. for your ac, check capacitor capacitance value if your meter has this setting, replace if its below listed values by five percent. Also check contactor coil for resistance. If below 15 ohms, replace it, its going bad. Also make sure high voltage connections are very tight. And as always shut outside unit power as well as indoor unit power off before any maintenance on outside unit.

[@lancerudy9934]

OL is open line.

[@acservicetechchannel]

Ha ha again! Thanks Lance!

[@ycnalcmot8993]

Some say over limit. Some say open line. Some say over load

[@Matts_Crafty]

some say open lead :)

[@tonymontecino]

Hello, I was checking a heat pump system that had a short in the control wiring. while I was trying to find the short I removed the fuse and install a 3 amp lil popper and as soon as I turned the power to the unit the transformer burnt out, it smocked. My question is, why didn't the lil popper tripped? FYI, the short was between E and neutral.

[@acservicetechchannel]

It sounds like that lil popper was hung up. I have my students use lil poppers in the classroom and I put faults such as shorts and their lill poppers open the electrical circuit within 1-2 seconds. I am not sure but what I would say is to find the short with resistance reading and the thermostat wires disconnected from the control board. If you need to put batteries in the tstat or use a mag jumper to do your connections then that is fine but you are testing for any resistance value between a potential hot and C or hot and ground, thanks

[@tinymanthebeast]

Can continuity work too right??

[@acservicetechchannel]

Continuity is the same as resistance but will give an annoying beeping noise. You should always go by the level of ohms read and not by the beep. You may think something is closed electrically but come to find out that contact has too many ohms across it do to burnt contacts, thanks tinymanthebeast!

[@bottitabaki3073]

Can you please lower or change the very first sound, it just so loud Thanks

[@acservicetechchannel]

Botti, the newer videos over the last 1.5 years have a quiet intro, better audio and video quality, thanks

[@steelod1528]

So do you have to buy a 3 and a 5 amp lil popper

[@acservicetechchannel]

Just the 3 amp one. You don't have that many instances where you need the 5 amp one.

[@steelod1528]

@@acservicetechchannel ty i appreciate your time

[@zekenzy6486]

Thanks you

[@acservicetechchannel]

Thanks ZE KENZY!

[@hvactechwanttobe1499]

hello i see you using Fieldpiece SC640 Multimeter and UEI DL389 what is the one you like best for HVAC

[@acservicetechchannel]

They work about the same and seem to have the same reliability as far as I have been able to tell! Thanks

[@Jim89240]

I understand that if any power wire touches common, a fuse will blow. But how bout a power to power short. Had a job the other day where the zone panel was putting out all theae crazy different voltages, pretty much just spiking up and down all over the place. Changed the zone panel and in turn stabilized the voltage but still something wasnt right, i had a call for heat on a paticular zone but it wasnt transfering over to the equipment side of the panel, eventually the problem was solved and R was in continuity with g when i rung it out. Changed the wires and call for heat transfered through the zone panel. Can you explain this? Im guessing what happened is power junped from r to g and backfed through the stat and bucked the panel with 24 v on 2 terminals at the same time. Kindof a mystery to me, i dont fully understand why this happened. Anyway your input would be much appreciated

[@Jim89240]

Also by my info can you tell if that zone panel even needed to be changed? After all i did get stable voltage on the new panel, and another thing i forgot to mention is that i replaced the tstats with a couple of t6's. The old stats were the white round honeywell ones that are supposedly power stealing, also when i had the new panel in the old tstats were compleyely out of the equation, which makes me wonder if it were those tstats producing those wacky voltages, i also own 3 meters, so i compared my readings on both and they were puttin out the same result

[@acservicetechchannel]

Usually a hot to a hot would not be a problem if it was all from the same transformer but it sounds like you had a hot from two different transformers touching, one from your zone panel and one from your air handler if it was g. That would certainly cause an issue, thanks

[@Jim89240]

@@acservicetechchannel holy shit dude, its funny you mention that, because the transformer for the zone panel was literally sitting right on top of the air handler transforner inside the electrical cabinet of the AH. They were literally right next to eachother. Is it possible power could have jumped from one transformer to anothrr in such a confined space?

[@acservicetechchannel]

Literally on top? That is not good. The magnetic flux lines of each transformer would be in the same area. Make sure they are not on top and at least 2 inches away from each other horizontally, thanks

[@reynaldohernandez5957]

Why is there a leak in the drain?

[@ltherealist3729]

What if the 3 amp fuse blows intermittently every 2-3 days.I checked all the low voltage and can't find anything.

[@16419leo]

I HAVE A CARRIER AC UNIT, AND THE FAN IS RUNNING CONTINUOUSLY, I REPLACED THE THERMOSTAT ALREADY, WHAT DO YOU THING THE PROBLEM IS? THE FAN IS SET UP AT AUTO IN THE THERMOSTAT. ANY IDEA?

[@acservicetechchannel]

Have you seen this? - kzbin.info/www/bejne/rYmWmXanrLqdoac - afterward ask whatever questions left, thanks

[@liverdelove]

Fan relay on control board welded shut. Normally open

[@chonghoshin6460]

Why 24 volt fuse blows on heat pump unit., it runs for day or two and fuse blow, it runs fine on emergency heat for several days but when Condenser is on it t blows 24 volt fuse blows in air handling unit.

[@JackTheAviator]

wish there was a video on how to test for heater furnace shorts , how to test each component for a short and what the readings should be, everyone skips that part.

[@scientist100]

O.L = Open Loop no?

[@justingrant7074]

Is the steps to locate a short on an electrical furnace similar? I have a 5amp fuse that keeps popping. I've been looking all over any can't seem to figure out where the short is, could it be the board itself? It's a 17 year old split York system, heat pump / air handler and electric furnace, that has had a fair amount of work done on it over the years but this year it doesn't seem to want to heat. AC works fine, fan by itself works fine, but when I turn on the heat the fan kicks on, the heat goes on, then a few minutes later the aux heat turns on and it blows the fuse. The outside unit kicks on and feeling the line even warms slightly when the heat kicks on, but not long after it blows a fuse. Earlier in the year we had a HVAC guy come out and after me repeatedly asking him to check the capacitor, he replaced the blower motor (twice, as the first time he said he accidentally blew it by reversing wires or something), and then after it still had issues (freezing up) he checked the capacitor and replaced it. Now I'm worried when he replaced the blower motor he messed up something else, or since he didn't seem to know what he was doing placed an incorrectly sized one that may be drawing too much voltage and is fine with AC is going but when the heating elements need to run pops a fuse...

[@acservicetechchannel]

So the fuse actually has to do with the secondary 24v side and not the high voltage primary side which is where the blower motor is attached to. You may have too many 24v relays which are adding up to an amp draw higher than 5 amps on the 24v side. I would have a new tech look into the added up amp draw of all the 24v relays or by using ohms law and testing resistance on all 24v relays, thanks

[@ronmurphy00]

Could you maybe slow it down a little for the people that aren’t so great at this I think that would help a lot of people or maybe I missed something maybe you’re just talking to repairman to do this every day not sure but thank you for the video

[@christianbaker535]

What is the probleme if the fuse always blows after 2 or 3 hour?

[@acservicetechchannel]

It sounds like a possible amp draw problem on the 24v circuit or an intermittent connection problem on the 24v circuit between one of the hots and ground or common, thanks Christian!

[@christianbaker535]

acservicetech thanks for the reply

[@hvacguy11]

Maybe someone can help me with this strange problem at least for me anyway. Customer replaced his thermostat. I Checked all the wiring and he showed me a picture of the previous wiring and it was correct. When I turn the heat on the fuses now pops I removed the jumper from R and RC and the heat turned on and fuse stopped popping obviously the AC dosent work now. The old thermostat had a jumper and as far as I can tell the wires weren’t moved. The Y wire was spliced in the ceiling and one end runs outside and the other goes to C on the board. Why does it work all of a sudden when I take the jumper out. I could not find any short and stupid of me I didn’t try and by pass the thermostat.

[@acservicetechchannel]

There is a short to ground between either the y and ground or common, or there is a short between the g and ground or common. Look up the video "acservicetech finding 24 volt shorts fast" thanks!

[@lancerudy9934]

O L is open open line.

[@acservicetechchannel]

Hey Lance, It can mean open line, over limit, open loop depending on who you ask but I like over limit, thanks

[@rocker8692]

Is it some where or some Where's lol

[@acservicetechchannel]

Maybe somewhereish, ha ha

[@rocker8692]

acservicetech thanks for videos,they are the best

[@JDT738126]

I thought the "OL" meant "open line"?

[@JDT738126]

Also so that wire shouldn't test for .04 ohms? That's a high resistance reading for that low voltage wire?

[@JDT738126]

Nevermind, so you essentially got a resistance reading across two different wire therefore they have a break somewhere under the sheath?

[@acservicetechchannel]

It can mean open line, over limit, open loop depending on who you ask but I like over limit, thanks

[@acservicetechchannel]

Yes the two separate wires were somewhat touching under the sheath, thanks!

[@MrRcerda0]

24 volt is going to the circuit board but i not having 24 v getting out to the the thermostat, is my circuit board fried.

[@acservicetechchannel]

If you measure 24v between r and c then you could try jumping r to g to see if the fan turns on, then r to w for heat. This would show if the tstat or the tstat wiring is bad, thanks

[@throttlebottle5906]

troubleshooting bah! just do what everyone I know does, call me :))

[@acservicetechchannel]

Ha ha! That is how I base my tests for my high schoolstudents, like a phone call and they have to describe how to test or fix the problem. No multiple choice!

[@morrisdaft8]

Thank you