Low Voltage Short: What You Need to Know

For some technicians this is a hard problem to solve.
But not for you because you are being trained by the master.
Video #1
Troubleshooting Low Voltage Short HVAC Basics Video
• Troubleshooting Low Vo...
Video #2
How to find a low voltage short HVAC Basics/ Process of elimination Video.
• How to find a low volt...
I hope you're having a blessed day and I hope your healthy and you're happy.
Please don't forget to subscribe hit the bell and definitely hit the like button.
If you want to learn more about relays and transformers check out the video
• How Do Relays and Tran...
Fieldpiece SC440 True RMS Clamp Meter
amzn.to/3rdGZ0e
Join this channel to get access to perks:
/ @taddydigest
Wanna Learn more about hvac? Check out my hvac tips for technicians playlist.
• HVAC Tips for Technicians

[@michaelrichards656]

Hey Tad, I spent half a day chasing a short on a split system in a hotel. I checked all the wiring at the condenser as well as inside it. I checked all the wires at the handler. I tried replacing the thermostat. I even replaced the thermostat wire. It ended up being a short coming from the solenoid coil at the reversing valve. That one hit me like a ton of bricks. It was a brand new system and I would have never usually gone there. 🤔

[@daddydaughterlilbrother7696]

Same situation here

[@KrisMoreno-uk9to]

Where is that at I had one at a hotel as well but it was at the transformer

[@kevinlawson8124]

I’m a HVAC from Port Allen, La. Keep doing what you’re doing, I can never stop learning!

[@TaddyDigest]

Awesome! Thank you!

[@jmead6121]

Good quick easy Find & versification ...sometimes its much easier on an pkg unit rather than running back & forth on an split but always same principle ..shorts used to be puzzling when I 1 st started out 35 yrs ago in HVAC / wasted quite fuses till i got an 3 amp popper ..started out with an 5 am popper & 1 st usage the 5 did not pop & got my xfomer the 3 woks great ..it will trip or so far it has ..100 % of the time ...also great tool out is an " A Zebra Brand or others " Short Pro Tool " that lights Up upon an R - C connection ...connects one lead to R or hot 24 volts on one side & then attached the other lead to each LV circuit @ Tstat or air handle / one @ a time while amp clamping the one lead to test for hi amps draw as you just showed also ....but connect to > G , Y .Y2 , W . W2 till light comes ON & you've found witch wire is shorted usually pretty quickly & now trace it back to the each of its components attached to that tripped wire & so many times its an shorted rubbed wire / Lots of bad Contacts / or sometime sequencers or bad tstat Great Video & Thanks

[@phillipmills4226]

We have been having a lot of issues with bad contacts lately. Using my ohms meter to check my resistance on contacts has helped me out if you have a low resistance you know thats the issue . Grab a new contact and check the resistance that will give you a idea what to look for. Great video!

[@michaelbt6777]

First of all, thank you for all your videos. The most weird short I had, it was in a unit that has the Common side of the transformer grounded. After a long chase, I disconnected the ground wire and the fuse did not pop anymore. It ended up being the ECM inside the air handler. When ramp up it was sending voltage back through his own ground wire, to the case of the unit. It was around 40V, enough not to trip the breaker.

[@TaddyDigest]

woah that is a weird one thank you for sharing that one with me you rock

[@jasonreist2528]

I never thought to make a pigtail for the resetables. I have a 3 and a 5 amp in my kit for the same diagnostic process. They really help isolate the trouble spots. Great teaching brother!

[@ncooty]

Great channel. Really appreciate your structured, practical, plain-spoken presentation style. You show what needs to be shown and say what needs to be said. I especially like that you cover the contingencies that you're _not_ seeing in a given situation. E.g., "OK, that blew the fuse, so we know X. Now, if it _hadn't_ blown the fuse, we'd know Y, so we'd do Z." That really shows that you're focused on teaching generalizable skills and not just showing how to solve a problem in this _specific_ case. Thanks. Hope you keep it up.

[@TaddyDigest]

Yes sir absolutely I am not doing these videos for me. I am doing these videos to provide experience to others. Thank you for noticing brother

[@carlosdclaveria819]

great video, I got my certification years ago, unfortunatlly I could not find a job. I leave in Illinois, and your video is great, thank you very much for sharing.

[@TaddyDigest]

You're welcome carlos thank you so much for watching

[@josephpuchel6497]

Hey I first automatically physically look everything over for bad wires , ground outs and any smell from burning contacts or connections. I usually pick it up during this inspection. Excellent video

[@TaddyDigest]

Good stuff joseph thank you so much for commenting and watching the video

[@NathanielTore-md4sd]

Thank mate for The Learning tips on low voltage..IAM a HVAC technician from Papua New Guinea..

[@TaddyDigest]

Glad to help

[@bill944]

I would've liked to see the ohm reading on the coil of that bad contactor. Had one dedicated to the heat strips in a Trane air handler earlier this week that was blowing fuses. That coil was reading .3 ohms and I believe the replacement was 12. Good video. I had one years ago with a rub out like on the second segment of this video except it was a compressor lead. Finished a p.m. and everything was fine but a huge lightening storm was rolling in. 45 minutes after I left my dispatcher called and asked if everything went well. I told him yes and he had just gotten off the phone with the customer and they didn't have any cooling. I went back the next morning to find a hole blown through the suction line on the compressor. Brazed it closed, just a small hole, and called it good but I was in a hurry because another lightening storm was coming in fast. That night the customer called again, no cooling. Went back the next morning, a huge hole blown out of the suction line and had some missing insulation on the compressor lead but I didn't have any missing insulation on the first blow out. Customer wound up filing an insurance claim and got a whole new system. It was good for them because the old system was R22.

[@TaddyDigest]

Great experience Thank you for sharing all this information ohms on the bad contactor coil was .7 And I'm pretty sure the new contactor was 15

[@keyronwiley2003]

Visual inspection is always recommended and important. I had a short today on the tstat wire for the condenser due to the wire rubbing against the metal cage. My meter did not show a short between the common and hot wire.

[@Ogtonyg]

Nice videos man. It feels good when you're a new tech and you know the answer before watching the whole video. Contactor turns on the emergency heat and blows the fuse then those coils are gonna be toast I'll bet. 👍

[@TaddyDigest]

Thank you very cool glad that you like this video

[@robertwilliams6288]

New to your channel I like how you take the time to explain what exactly you are doing with your analysis on the unit will keep watching. 👍

[@TaddyDigest]

Thanks and welcome

[@deanburke3041]

This stuff is very easy without a lot of experience.

[@TaddyDigest]

That's correct

[@hezekiahanderson5655]

Love your content dude. You don’t even know how much this is helping me grow as a new tech ! Thank you so much ! 😭

[@TaddyDigest]

You're welcome my brother so glad that you like the videos you're the reason I do the videos. Please join and be a member and check out my member's only content.

[@jackfrost5132]

Great video, like how you explain it for the simple man.

[@josh3386]

Thanks for all the videos taddy! I finished school recently and I’ve been working as a tech for 5 months now. Your videos really help!

[@TaddyDigest]

That is awesome!

[@aaronserrano4118]

That tattletale fuse is a game changer. Never thought of using something like that but then again I’m green to the service world since I was piping fitting for most of my apprenticeship. Definitely gonna add it to my set up. Love your vids, has definitely helped me out with the controls/service path I’m taking 👌🏼

[@thefreshride1510]

There is a fuse in AMAZON called lil popper. It helps to find shorts and you stop waste fuses

[@TaddyDigest]

Glad to help ☺️

[@aaronserrano4118]

@@jacobkennon9603 not true but ok 👌🏼

[@thefreshride1510]

@@jacobkennon9603 no

[@aaronserrano4118]

@@jacobkennon9603 you sound like a fraud yourself. Go for a soda bud

[@williamjohnson9282]

I dig having the ammeter on when checking for shorts, I've made it standard practice to ohm out contactors on my PMs, saves us a trip on service plan customers, and adds value to a Billable PM/cleaning

[@TaddyDigest]

Very cool Glad to have you here Thank you for joining please send me an email at @[e-mail] I have a bunch of guides I would like to send you

[@1madrs637]

I got one for you, have had 3 techs at my house. My 3amp in air handler would pop, I would replace it and it would last a few days until it popped again, eventually the 3A would just pop immediately. Tech came out, put a 5A, same thing, would last a few days, but after a couple fuses it would just pop immediately. Had a friend try to chase the short and all he could get was that it was outside. Replaced the board, and replaced the contactor. Still pops the 5A when we put the main fuse back in. This happens now with no power draw, both thermostats are set to off, and outside big handle fuse is pulled out. Still pops the 5A in air handler. Had a tech recommend replacing my signal wire from air handler to board. But that was just a guess from him. Any help would be nice lol

[@deanburke3041]

This is all the easy stuff for dummies. No wonder it's free.

[@kendrickanderson6313]

Great educational video for hvac techs. Continue being a force for good in the hvac industry Tad. I live in Memphis TN and I'm working on getting my cmc-c license. I'll be attending the prep course in Nashville on March 30th. Peace ✌🏾

[@TaddyDigest]

Thank you Kendrick That's Awesome news The prep course will be great You can do it

[@peterman8058]

Nice work!

[@PBS-nm1uu]

thanks for all the info

[@aarongray503]

Out of curiosity what hvac call had you stumped the longest and what was the problem/fix?

[@TaddyDigest]

that's a good question 🤔

[@ethandenny7242]

Would like to know as well, thank you

[@taketinnn33]

Appreciate the linked vids in the description section. Solid work, thanks

[@TaddyDigest]

You're welcome Let me know what content you need and I will be here to make it I'm here to help

[@taketinnn33]

@@TaddyDigest Anything and everything electric related is great for me because that's where i'm still the thinnest.

[@GARGOLASPERFORMANCECOATINGS]

Much appreciate the vid, the resetable fuse is great, I will be making one like the one you've made for sure ! Thanks again !

[@TaddyDigest]

No problem 👍

[@KrisMoreno-uk9to]

Hey tad where can I get that fuse popper

[@mjvick]

The test circuit breaker is 32v. Does that effect the amps that would trip it .. I guess it’s more amps at 24v?

[@robertspadezhinton]

Can i use a 5 amp fuse popper to do the same job as a 3 amp popper..?

[@TaddyDigest]

yes

[@chrislester3152]

Hey I had a 12000 btu mini split and a 18000 btu and I had these on twin breakers or the 12000 was in the same as my fridge and it was giving me a pc04 error code and it also went into a defrost mode randomly at 50 dagrees but I cured mine by taking it off the twin and I can put it back and causes it so it’s definitely the twin that causes it but I was wandering if you could explore and do a video about this because I see this a lot online and it would help alot of people to understand how the inverter compressor gets confused by the small milli volts that causes this , thanks for ur videos and hope to see one about this cause and cure

[@alfredhines505]

Hey Tad, I am Hines, from Florida. Today I have a service call that is giving me a hard time. The Air handler is not coming on . The 3 amp fuse was popping I change the contractor but the x13 motor still not coming on. It is getting the voltage. Is the motor module is defective?

[@TaddyDigest]

kzbin.info/www/bejne/qXXWpWWElMuVetE Here is a video to make sure the ECM motor has a call and voltage If it's got voltage and it's got a call. Then it could be bad for sure.

[@07JR]

Good job sir

[@TaddyDigest]

Thanks

[@TonyRodriguez-ok2ix]

Good stuff

[@TaddyDigest]

Thank you my brother

[@emtken2004]

I always grab the resettable fuses from old units before scraping them

[@TaddyDigest]

Me too man Good stuff

[@ranasultani9841]

Great man

[@deanburke3041]

A nail thru a stat wire behind some molding in a closet shorted the circuit in a church. I use a Lil Popper.

[@TaddyDigest]

glad you found the short brother Keep on keeping on

[@sharky5570]

Great stuff Tad

[@TaddyDigest]

Thank you 😊

[@roqueherrera8471]

TADD I’m from Dixon CA

[@roqueherrera8471]

Eres CHINGON

[@Eddy63]

Good info Taddy ... Thx for posting ...

[@TaddyDigest]

You're welcome thank you my friend

[@donaldatkins2942]

Awsome video thanks you for help

[@TaddyDigest]

You're welcome Donald thank you for watching

[@adolfovazquez8427]

Thank you nice video

[@TaddyDigest]

your welcome

[@eliasmoreno82]

Hi ted i have a problem with my electric furnace i recently replaced sequencer and limit switch and the heat strip glow ,when i turned back on the power my thermostat went blank no 24v already changed i checked transformer and 240v input but no 24v output i changed transformer but still not 24v pls help me

[@TaddyDigest]

you have a short

[@thefreshride1510]

Good video. I was waiting for this video yesterday but i could not to see it at time

[@TaddyDigest]

Thank you I'm glad you're here and I'm glad you watched the video

[@GainsorGainz]

Was working on a small hanging heater for a building. Transformer was shot and replaced it with one with a resettable fuse on it. Found the exact same problem with the coil on the contractor shorted

[@TaddyDigest]

Good Job 👍 thanks for sharing the experience 👍

[@ChapoTheCorgi]

Love the vid! I like the diagnosing videos you post

[@TaddyDigest]

More to come!

[@TonyRodriguez-ok2ix]

wires rubbbing on metal/copper is a common problem

[@timdelgado9710]

You’re a beast

[@TonyRodriguez-ok2ix]

when thermostat is bare no conduit it could easily get damaged.

[@The12stonesfan]

Hey Taddy, good troubleshooting. I guess now I need to start watching out for contactor coils hahaha.

[@TaddyDigest]

Thank you They can be shorted Sometimes you can smell it the burnt smell

[@Edmocci]

You’ve got to be careful using circuit breakers in place of fuses. They take much longer to open than a fuse since it is a bi-metal. In the time it takes to heat up you can certainly smoke (or de-smoke) a board. I understand it’s temporary for troubleshooting but you can burn things up while testing. Obviously you could de-rate the CB to compensate for the time lag but there’s not that big a selection.

[@TaddyDigest]

Great knowledge thank you

[@destroyer.e]

😂 Yo I’m signed up to your upgraded version how do I get some guides from you?

[@TaddyDigest]

Awesome Send me an email here at [e-mail]

[@roqueherrera8471]

Nice CARNAL

[@bellamaesuniverse6462]

Thermostat was not powered on, Transformer was burned when i arrived and the fuse was still good, replaced the transformer and system turned on, went to the tstat and it was showing low voltage. Went back to the attic and transformer was toasted and fuse popped. Went to the condenser and Contactor was toasted. Ohms on 24 side was at 0. Replaced fuse transformer and contactor.

[@alfredhines505]

Hey Tad, I joined.

[@TaddyDigest]

Awesome, my brother. Thank you so much for joining. Here is my email [e-mail]

[@aaronclark1599]

What would cause my fuse to pop when all T-stat wires are unhooked?

[@TaddyDigest]

Something in the unit Or thermostat wire

[@sonnguyen-ve7gn]

Hey Taddy, I already pay for joining the membership but I can not watch the video.

[@TaddyDigest]

Hey You have to be a level 3 member to watch any of my member only videos Make sure that you are a level 3 member Also make sure that you get my email [e-mail]

[@roqueherrera8471]

TADDY BEAR SAVES THE DAY!

[@roqueherrera8471]

I always pull them off the junk Lennox RTUs

[@sonGOKU._.]

Do anyone find resettable fuse link?

[@TaddyDigest]

I can put one in the link into description

[@sonGOKU._.]

@@TaddyDigestplease do

[@TaddyDigest]

ok deal

[@dwghtcrook]

I have had several low voltage problems. and it ended up being.customer put a nail in the wall.and split wires

[@TaddyDigest]

Oh that's a good one I bet that 1 was a pain in the neck

[@yonkromis7883]

You keep saying short but that wasn't a short a short is 0 Ohms

[@eatcommies1375]

Sorry to sound like noob but what exactly is “emergency heat”?

[@keyronwiley2003]

Emergency heat is when the electric heat strips are being used to heat your home when your other heat source isn’t working.

[@sonnguyen-ve7gn]

Yes Sir. Can you send your email again. Already $5

[@TaddyDigest]

absolutely [e-mail]