This is part two in our low voltage, diagnosis, video one thing you're going to notice is that it's cutting back and forth between a system that i'm working on a heat pump and then a straight cool unit. That bird is working on with some apprentices, and these are actually happening simultaneously, but we're kind of cutting between them so that you can get a sense of a couple of the problems that we're diagnosing in order to make it more enjoyable. Just to kind of attempt to follow, along with us, diagnose as we're diagnosing, there's kind of some strange things that show up along the way. But that's how it goes in the field.

Right things happen, and i don't want to edit out the the good with the bad also before we even get into it. I know some of you are going to comment about the blood spot on aaron's back. It wasn't a big deal. It looked like he jabbed himself with a nail while in an attic, nothing, nothing major but uh.

You know hey. Sometimes, sometimes you bleed a little in our trade. The people taking the video really wanted me to make him change his shirt, but i thought you know: hey, look we're doing a class. This is real life.

This is what's happening. You get to see the unvarnished look at what it looks like teaching at our offices. At kalos and we're going to go through a series of a couple things, so we're going to be splitting up and starting on a couple different units, but i want to start with a couple more simple things: um eric has one, and then i have one. So i want to start with one of the most common problems that i see, texts do and that result in shorts and all kinds of problems opens whatever they'll take a wire, regardless of whether it's eight wire, two wire four by five or whatever.

It is, and they'll do some version of this. What's the problem with that they just potentially - and i actually i don't know if i actually did or not, but most people when they do that they're gon na nick right there. So, what's the right way of doing it come here aaron i want you to come demonstrate come demonstrate for all of us with your crocs and socks. You are wearing crocs and socks right now all day.

I appreciate that yeah. You can't see them okay, so he still stripped around it, but now he's going to grab one conductor and he's going to all right. He's he's struggling here a little bit all right. That's that's fair enough! Fair enough! We're done here! We're done here! I want somebody else to give a demonstration bert come on or uh yeah bird yeah we'll have bird.

Do it i'm going to cut down the outer casing to create a line i'll make it easier for me to tear down this line so he's making a split in the casing that now, when we grab either the string or one of the conductors, it will follow That split and it will come apart, a lot easier, yep and i don't see a string available here, so i'm going to use a conductor collar that i'm probably not going to be using and take it so in on a heat pump. For example, what if you're using eight wire? What are the conductor colors, you generally don't use brown black are the most common yeah, i'm going to take it and tear it down the side, so i'm actually tearing the casing and then i'm going to fill the casing back like this. So now i have a point: pull this down a little bit to show people that i did a good job when they come later. You actually know how i did this yeah and then i cut off the point that i first cut into to make sure i cut any nicks out so then i'm ready to yeah ready to go.

That's exactly how you want to look so then you can cut your extra off and it's actually rolled back. So now it's it's better, not looking nice, there yeah it makes it you, you roll that into the metal metal edge, so the metal edge doesn't cut in through the wire when you're sticking it into the unit grommet. I think it called a grommet okay. It's like a homemade grommet, you just roll it up and stuff it in okay.

I've got it. I don't know what you're talking about, but that's fine. So the point is is that the point is. Is that i don't on a on a thermostat wire? I don't want to see you doing any ring around the rosie, because, even if you cut off the part you ring around the rosie later, it's still not an ideal way to strip through when you cut into it this way.

Now it gives you a path that you can then peel away. You agree with that. Eric it's very possible yeah, okay! Well, i mean, if you have a string and it's but again i don't like your way, my way's better. Do it my way? It's simple! It's really simple: it's almost impossible to grab on that string right, even though you've been doing it.

The other way, this entire time you're absolutely going to do it my way now, yeah, i'm sure i i'm sure i'm certain of it, okay. So what's that? No, why are not off all the unused ones? No, not generally, i mean generally in residential, we're just wrapping it back around around the base of it, but the most common causes of problems uh in especially in newer installations, are what we just talked about ringing, bringing it nicking it pulling it through and nicking it Or scraping it when you pull it through the equipment in residential new construction, especially when metal studs are being used. One of the most common causes are pulling it through a metal, stud and chafing it when it goes to the metal stud, so anytime, you're running a conductor of any type through anything, you need to make sure that there aren't any sharp edges at all and the Best way is to just always use grommets use a designed, grommet or connector, rather than just pulling things through metal openings. Just a just important practice also think about where we're going to route this.

So, let's think, let's talk about a heat pump for a second, so in a heat pump, if i'm routing some wires into an air handler, if i'm routing some wires, we've got to pretend this is a heat pump here, i'm routing some wires into a heat pump Through where the evaporator is, i think, to myself. Well, it doesn't matter if this touches the evaporator right, because the evaporator is cold, but the problem is: is that in heat mode that evaporator coil can get pretty warm? Now a lot of people will argue and say yeah, but it's not going to get hot enough. That it will melt the conductor yeah, but what happens if there's a system failure like a failed, lower motor, something like that it can potentially get very hot. So that's just an example.

Think about where you're going to route your cables and make sure that they're not going to be touching anything that's going to either melt the jacket or just vibration over time is going to damage the conductor. So those are all important things to consider next thing. I want to do here is i want us to go ahead and wring out our wires. I want everybody to actually come up here now.

Actually, i'm going to let ryan do this so go ahead and go ahead and get both ends stripped back on this. On this conductor, let's grab a meter all right, so we're going to have josh here you go josh you're gon na grab the meter well, but before you use the meter at all, what's one of the first things you do that we just talked about put it On home scale ring out the yeah, that's right. So now it's not gon na okay, because yeah you're on the mega home scale. There you go there, you go.

That's fine there! You are all right. So we know that our meter is working now go ahead and strip off the end here, but i want you to go ahead and you don't have to actually measure it, but if i measure right now between any two of these conductors, what am i going to Measure with an ohmmeter - i'm not exactly sure, but i know you're going to measure something you're going to measure open or infinite. So there's a measurement, but the measurement is no path open, right, infinite, ohms, because why, on the other end, those conductors aren't connected to anything right now. If i want to confirm that there is no break in these wires between here and there, how would i do that if you were checking for a short, that's something you might do, but this is the key thing: if there's a break in one of these wires, What is that called? It's called an open right, so i'm checking for an open and if i'm checking for an open, i'm looking for a break, i'm looking to find where there is no path where i would expect there to be a path right, and so this is a common test.

Now this isn't always the way you would do this, but i want you to know how to do this. I want you to know how this works, because this is an area where a lot of new techs get confused, because somebody will say especially a lot of senior techs who, like the method of owning out wires. That's actually not my favorite place to go to, but some people like that and they'll say: did you own out the wires and they'll say yes, i did but there's a lot of different ways. You can oh mount wires right.

So this way that i'm about to show you is a way that you own out wires to confirm whether or not you have an open. So what i want you to do is strip back those wires a little bit longer or actually, let's just do we have a wire nut sitting around here somewhere, so we're going to connect all of those wires together, all those conductors together and then we're going to Measure yeah just connect them all together, so you don't put that you don't put the two probes in the same place at the same time. You put this one over here there you go so now. What do we know, because now, connecting from one conductor to the other is the same as connecting both meter leads together, which means what which means close.

We have not available 0.4, so we're measuring a little bit higher resistance, but they're essentially the same. So that means that these wires are completely intact and we can measure all of them together. So we could measure blue and white together because they're connected on the other end. We would expect to see that right, but now what happens? If let's go ahead and take a go here and mess it up hard to watch, isn't it that's a fairly realistic break that you could get you know yeah a mouse, choose it! Something like that now i want you to measure between these and see.

If we have an open anywhere all right, so that means that okay but hold on what did we learn? We don't have a path between green and white, but what does that tell us eli? What does it tell us where, on one of those on green or white right, so now we want to figure out which one it is. If we can, is it green or is it white? So what do we do? So, let's go from green to a different color, ah all right, so which one is it it's white all right, so go from white to every other color and see if you get anything nope yeah. So we know now that we have an open white, an open white. Do we do this test? If we have a, i don't know blowing fuse.

Is this a test you do if you have a blowing fuse? No, is this a test you do? If you have a long fuse, is this a test you do? If you have a blowing fuse, it is not a test, you do if you have a blowing fuse. I want you to really get this in your head. This is a test you do. If you have a circuit, that's not energizing when it's energizing here, but at the other end i'm not getting anything so now you can check to see all right.

Where is my open, but you can also just use voltage. Do that go ahead eric? What? If i told you, i would check that if i had a blowing fuse, because i would want to check if my common wire is shorted to any of my other hot wires without wire enough without wiring. In the end, you're not checking you're, not checking for an open yeah. We're saying that the the time that you would primarily do this test is going to be so you're.

Okay, so explain to me again: does anybody do anything sure yeah? But if, if common was rubbing out okay on one of those wires, okay, it would cause a blown fuse right. He could test that by jumping all the wires together, but leaving common out of the wire nut and then doing the test in here to see if any of those wires had a path to comment. Okay, yeah sure sure, but not, but not specifically. This test that i just showed, but a version of this test yeah, you probably wouldn't need to wire, not everything together, because you had the path you'd.

Have it pretty much all the time right, but you could yeah that probably again, probably wouldn't be the way. I would do it, but yes, that is a possible method, but again the key thing here is understanding what we're trying to test for what we're looking for not confusing, opens and shorts opens you're mostly going to have something not happening. It should be happening. Shorts you're mostly going to have a blown fuse or you're going to have circuits energizing when it's not their time to energize.

But all this starts by first understanding the system enough to know what's going on here, because that's what we're going to get into here in a second is doing some diagnosis on what's going on and then working into the the actual diagnosis. I want eric to come on up here. Eric come on up and i want you you're, so you're gon na have to hold your mic. I want you to demonstrate why you set this up and what it what it signifies.

This is the situation that we ran into earlier. Where we had the wire inside of the air handler. We can identify the colors, but the one outside was so baked in the sun. We couldn't identify, we had two whites and two yellows.

I want you to touch one of those wires to ground, but not all of them, so that one color is color is red. So we would mark that one red right now that one's identified. So what this, what so, what he's saying you would do in real life is, if you can't identify on the outside, you could just take these and connect them to ground if you have a good ground, but we just confirmed that we did that test alone, confirmed If you did, if you checked all of them and none of them rung out well, that's very likely. You don't have a good ground path, but we use ground.

All i did was just took this red wire and touched it to the metal frame, and then she checked each one to the copper, which is also grounded and could figure out. Okay. Now this is red, so i'm gon na do i'm gon na. Do the next one here? Okay, what do you got three red and green? None of them were labeled if they were all the same color wire.

Even if you have the same color wire on his end, he could designate a color and you could designate a color outside if you had eight black wires one red exactly so. Do you all understand how we're using the ohm meter here and i like to start with the ohmmeter, because it's the easiest one to just intuitively understand is looking you know, you're looking for a path, you're checking what we call continuity. Continuity is just a path, no path test, we're not looking for a specific ohm value or anything like that. We're just looking for do we have a path or don't we have a path, but in this case we're using it to identify.

Do we have an open circuit or to identify what circuit is which again, that's not going to be super common, but you get why knowing how the meter works leads to these sorts of solutions all right. So now we're going to split up. We've got two different systems here and i want to set the rules like i always do. I don't want us to guess.

Guessing is the enemy of low voltage. Diagnosis here is the impulse the impulse is to get close to where you think you have the diagnosis and then call a senior attack. That's a really bad habit. Call the senior tech once you've already done.

Everything and you're already sure you're sure then call to double check if you just want to, you know, make sure you're not making a mistake, but don't call with half-baked information and some guesses thrown in. So that's the same thing we're going to do here. So each one of these systems already has a problem built into it: you're going to energize the equipment and you're going to find the problems, and then we'll do as many of these as we can alright. So you are not allowed to open the boxes in this case on this gas furnace.

It's the box behind the thermostat on this one. Here it's back behind, because i that's where i will create problems open shorts, those sorts of things. So our main team here people touching tools i want to be aaron and tanner - okay, aaron loves low voltage. Shorts he's really good at finding them.

I know i'm not telling you it's a low voltage short either. I'm not telling you it's a level destroying a couple. Other things we've got some magnetic jumpers here. If you want to use them and we have a couple of the short pro tools, so you can use these and place your fuse.

So that way you don't keep blowing fuses. So i'm just telling you there's a problem. I'm not telling you what it is aaron, let's go, we got, we got a meter here, we got uh, we got a uh driver here, let's start with again knowledge of the equipment. What do we know so far? We know it's a heat pump.

Okay, um. We know that it's indoors - okay, both of them blower, is going all right. So what do we know? We know our blower runs. Okay, compressor fan is running okay, i know our refrigerant is flowing through.

Okay thermostat is on. Okay, float is dry, okay, so everything's working. Okay, yep, it isn't cool things wrong with this thing, that's okay! So what can we see on the thermostat? Nothing, nothing thermostats, blank! Okay, so where to next float switch, that's a guess, but yep, it's a good one! It's a good one! Okay! Is the system receiving any voltage? Okay check the breaker? Let's start at the basics, do we have power on at its source, all right so check the breaker somebody anybody? So we got the breakers on all right. We won't have power okay.

So let's go look next because we've got the door off okay and it's not all right. We've identified identified that so we have a switch on the door. We already know from experience that keeps power off to our to our circuit board and power off to our transformer right, all right. So, let's close that switch.

So let's go ahead and tape this shot. So i had. I had set this to a be fine. It straight hole, cooling.

I know why it should have been in heat mode right. I know so thermostat. So why isn't it in heat mode? So why isn't it correct? So that's interesting now we're finding a different problem than we originally even thought. We were finding so that was that was the problem i put in.

It was supposed to be right programmed incorrectly right, and i was going to test you to see if you could catch that, because you've never made that mistake before. Actually, i used to make it all the time i know so it was in cool mode. We wanted heat, we don't want it, we don't want it to be in heat, but it wasn't in heat, it wasn't in heat when it should have been in heat yeah. If the problem was not what we originally thought, which was that it should have been running in heat based on how i had it set up now, let's go ahead and run it in heat and see if it does run in heat.

So what are you doing? You're you're just touching, to make to see if the to make sure it reverses out switched over correctly tips, you're going to feel heat here, you're going to feel cold, so it is running and heat now too yep. So for some reason it was energizing. The reversing valve, even when we had it, set up for a straight cool unit, yeah, which is kind of interesting and the reversing valve is coming off, so it is properly running. It is not short, yep, okay, so anyway, we're not going to focus too much on that, because uh that's kind of weird yeah, i'm not really sure why that happened, but uh still programmed for that.

Wasn't my expected behavior now, what's the danger of doing this? What's the danger that i'm doing right now run and say you're gon na pull in, but i'm doing this with power and that and there's power on the back side of the switch right. Oh yeah, yeah, yeah, so yeah you can turn off power before you. Do it or actually know exactly where to touch and not to touch our switch. Is now closed.

What do we have nothing still blank thermostat we're gon na have to start moving into diagnostic. Now we just tested our meter on live camera, so i think our meter's working, but where you want to check yeah, i'm gon na check. If we're getting any voltage to the board, i don't see so voltage coming into the board, yeah so i'll open. If high voltage, you could check it there, but it does plug into the board.

It's probably more accessible there to see if you have high voltage, but what but what voltage powers our board 24 transformers yeah. So we could go straight to the transformer and see if we're powering it where's the transformer plugging into the board here. So this is our power supply to it. This is the high side and then the 24 volts comes out the other side and right here on red and blue okay.

So that's where you could check if you have voltage coming out of the trans transformer, so we're switching our meter to what vac checking for 24 volts between what what's coming out of our transformer here, the red and uh yep. So one side is going to be our hot and the other side is going to be our common all right. So what do we got going on all right? So we don't have the blower's not going system he's not in delay. It does have battery it's in it all right, you're always checking he's checking the float, which is a good practice to start batteries out and system shut off, which means red, okay.

So all right. So, let's just talk about what you just did so i'm interested in that. So you heard it go on and click off, but then you remove the batteries. Why did you do that? I did that because a lot of times the float stitches, the float switches will trip and if the batteries are still in this you'll still have it just display all right so you're, basically using that in place of a in place of a meter, i mean you Could have pulled the face off and checked with a meter, but instead you just use that and i'm all for that.

That's a perfectly good way to do that. So what you know is is that you have no, what we have no 24, no 24 volt power right, we're not feeding the thermostat now. Does that mean that the problem is in the r circuit, because r is our 24 volt power could be common too right now do we do we suspect that we're not sure i'm not sure yet, but what did it do when you first turned it on what What happened it kicked on it clicked and then it shut off so what's most likely because it did kick in, we popped the fuse. It's most likely that you popped a fuse right, because if it was, for example, a common that was completely disconnected, it wouldn't have come on and then gone back off again.

So using your senses, i like what you did with the batteries using your senses to diagnose is always first, so let's go ahead and get it open. So we need to check between that. That's what creates our 24 volt circuit you can see. So should i take that off or it'll probably be easier to reach? If you take this off yep there's a couple different ways: you can do this, but let's just give you a little room so put your meter in on the side of the spade on blue touch the metal behind there down here, and then you meter on red On the other side, and what do you got okay, so we got no voltage coming in to our coming out of our transformer okay check if we have any going in yeah, so we need to check if we got any going in okay, so this would be Uh one leg here and one leg on any of these neutrals: all the neutrals are tied together, so find that spot where you can touch metal, neutral, no voltage, so we're still chasing our problem back further and further to power supply.

So we're not getting nothing from here, and so, where does power supply come into the board from from the switch from switch, so power will come in from our breaker and, like you said, first go into this junction box and from the junction box it'll be broken By the switch and then straight to the board, but what did he do i can't tell from here? If they are, they look like they are. So, let's just look at the diagram. Real, quick and it'll show us on the board, which one of these is power. Coming in from the switch, so we're looking for line 1 is right here, so l1 is going to be our power coming in and you see how it goes through.

The switch right here comes in and then connects to l1, so we'll check on l1 going into the board. So what we're checking is, is the power coming into the board and just not coming out to the transformer, or maybe it's not coming into the board at all. So we'll go straight to the power source, we'll find l1 on here and check that yeah yeah. It is, you have to come in from the bottom to any neutral, yep nope, okay.

So what have we learned so far, then we're not getting power to the board yeah we're not getting power to the board and we're not getting power to to the transformer. So we don't have power to our 24 volt generator, the transformer, and so now we got to keep chasing power back. Where are we going to go next? Where do you want to go next? What could happen in here that could break power? What human error uh? No yeah not wiring it right, but if it happens suddenly, what's another thing you could do wrong that later on would cause a problem screw it in there right, yeah, some kind of a wire knot right, there's a connection loose connection, yeah loose connections, so it could Be a wire nut, loose connection in there okay or same thing on the breaker, so before you're sticking your hands in there, you would want to check and just make sure that it's off and you'd want to check each leg to ground on this one. Here that's going to be kind of tricky to do.

You would actually either check it at the primary of the transformer or you could just kind of put a lead into your uh. Your wire nuts um. So go ahead and do that quickly. So we are now on.

What's so before you before you even do that we're going to put it on ohm's scale, you already did it okay, good all right all right, so you go each one to ground. That's a safety check because sometimes because you could have just one leg: that's energized, yep and that actually commonly will happen. You have a disconnect or a breaker that has one leg: that's still connected, pull it or you pull a disconnect and one of the metal pieces gets stuck in there. Yep get a good little it's a fun day.

When that happens, i got zero. I tested both okay, so we're good all right so now now, what are we looking for now we're looking to just confirm that our fuse did pop? Did it yep? Okay, so it blew now. My suggestion is going to be to go ahead and pull that out and put in. I was going to put our short pro pro, which, in this configuration, is actually kind of tricky to do, because you have uh alligator clamps, what they uh yeah.

So this works as a fuse and it just doesn't yeah it works as a fuse. It just doesn't pop. It gives you a light instead pretty hard. So there is our blown three amp fuse, which he found pretty efficiently turned on and then blue.

So now we got to figure out why that's happening. What we don't want to do is just keep putting a bunch of these in there and wasting them, so we replaced it with a short pro to save fuses, we're using something else. Oh okay, where did that? Come from, it's got a reset button on it: okay, which is right here, yep, so that one will just trip. Okay, that's a good one! I, when i'm using these breakers, i always prefer to use the three amp rather than the five, because they're going to be more prone to trip more quickly, so we don't damage any circuits, exactly exactly yep, go ahead and turn off the power whenever you're opening up A electrical box like this that maybe potentially has a loose connection inside or you know, has high voltage, kill your power first same thing he's doing here.

He kills the power before well. There's a fuse here, but we haven't. We haven't needed to check it because that's our 24 volt saying this after yeah right. So if our transformer is not even putting out, then we're not we're not worried about the fuse, yet there is voltage back there.

So what's a better way, he could do this. Okay, you can pull the disconnect right. This would be. I guess this is symbolizing our breaker panel, so you don't have that option on the breaker panel or we can unplug it so go ahead and take this off.

We do have a plug here that we can unplug, but you wouldn't typically see that on the unit this symbolizes, our breaker panel in the garage you're gon na, have to take that off without unless it's sketchy like that, then you can kill maine to the house Before you take it off nobody, nobody sees our problem. Yet anybody in here all right, mario you're right what what circuit are we doing? What voltage are we dealing with for a furnace? I mean yeah, 120, 120, you're right and so we've turned on. We we have both of ours, we had them all on it. Were they all on yeah, oh okay.

Well, maybe brian set up our problem inside our electrical. I thought you only turned on this one, no okay! They were all on here, all right. So now we got them on, let's find out, if we're actually getting voltage out, checking between hot and common coming out of the breaker arming uh between hot and neutral yeah. There's overcoming power first right, yep go go ahead and check the incoming power.

First, that's not! Actually, our incoming that's our condenser, so your incoming is going to come into the top of the bus bar, oh ready, so you have 240 and then neutral. So let's check our 240. well we're going to check between our 240 first. So we have 240 and a neutral, but we're going to check 240 that will allow us to check.

Oh, you can't see it. That's what your problem is. Oh there, it is okay, all right, so our main breaker is off, be like the same as a main yeah. You want to go so we're just slowly chasing our power back to its source, apparently a new main breaker for the house.

That would be commonly, but you would check the main breaker and if you weren't getting it there, it would be an issue with the meter or a power supply to the home to check one leg at a time. Then you would go to the ground yep. Then you would go to neutral would be the most accurate there yeah instead of ground of the box, yeah, so uh, apparently the the entire training unit was not plugged in. I hope that's actually what we're supposed to be finding otherwise we're gon na plug it in and then start over and find the real problem that brian created short pro just uses a light as an indicator, so you're not actually tripping at all all right.

So now what are we going to do so now? We know we had a blown, it blew a few and it kicked on and off right um, which means we weren't getting 24. um. Well, we weren't getting 24 because the fuse blew right so now. What do we, what type of system fault do we have? We have a short, we have a short okay.

So now we need to identify where the short is exactly and we want to figure out exactly which circuit it's in and then we can figure out exactly which conductor it's in, and we can do that a couple different ways. But i want you to approach it. However, you would want to approach it first, so normally with this, i will unwire separate my air handler wire going to my thermostat and my air air handler wire going to my condenser, okay and i like to wire nut them and on them out. Okay, that so i'm fine with where you started there, but don't wire up them and we'll open them out, because wire, nutting them and owing them out is the test that we did for an open, not for a short, so we're looking for a short right now.

So i would suggest, do the same thing: pull them out, unhook them, but do not unhook common. Do not unhook common. We need to keep the common intact in case. That's where the short is shorted too, because that short, that's blowing, the fuse could be shorted to ground.

It could be shorter to ground, but it could also be shorted to the other side of the circuit, which is common, which electrically on this unit is the same as ground because ground, because the common is dedicated to ground. It's actually grounded on the common side. So just another way to approach it. I would unplug the low voltage wires from the transformer and just start sticking meter leads into wire nuts to find the circuit that's shorted, to either common or ground.

Now on this one, this one, so you would actually just start buying multiple blue ones. I would pull these. I want you to use eric's method before you use my method. Well, let me get the correct size wire nuts, on this uh somebody put some falling off.

One time, okay, i appreciate that. Look at that. I did it. They just kept falling all right, so eric's method is using an ohm meter on a de-energized circuit, which is better for a couple reasons.

One of the reasons that it's better is that you're not going to shock the circuit by continuing to energize it, and the other thing is, is that if we can get good connection without pulling the wire nuts off, this is the only downside to this. It's a little bit more of a pro move. If we can stick in there and get a connection to it on the other side of the wire nut, we don't even have to pull the wire nut off. I would also be doing a good visual inspection, though on any of the field.

Wiring connections and even the factory ones, to make sure something's not rubbed or crossed either way, doesn't matter good question. It's a service call as soon as i take off the panel, i'm looking at the wires that are wire nutted all together and i'm trying to confirm what wires they have going to wear right, potentially damaged yeah. And that's that's a good point and also look at the thermostats exactly if somebody recently replaced the thermostat. So does it look new, that's an indication because that happens all the time.

What's a common mistake that customers make that results in a blown fuse when they wire up a thermostat, they don't shut the power off. That's a common one and the other is that the equipment with the reversing valve yep, and also making sure that it's set up. Not that the the thermostat doesn't come factoring from straight cool or factory for a certain way. That's a big one.

Another one is a lot of, and this isn't older ones, but a lot of thermostats had a b terminal and they would say b blue. They would hook blue to the b terminal, but b is actually the heat mode, reversing valve call, and so when it goes into heat, it would blow uh below the fuse that way. So you'd get a bunch of those calls 211. yay.

We have power that power. Now we started our blowers running. This is pretty exciting. We currently are not blowing a fuse.

We have a blower running, but our condenser has not come on. Yet we're not going to be able to cool this customer's house without the condenser coming on. Are we in cool mode? All right cool on is flashing, so our thermostat is in time delay. It'll only be five minutes.

Delays can take a long time. It's really easy. Okay, oh good! Go ahead! All right, so jessica looked up the manual on the thermostat she's going to remove the time delay and we won't have to keep repeating this time delay process to save time, instead of because we can't immediately find this model online we're just going to bypass the thermostat, Because what's happening is that the time delay just keeps repeating, so we got something causing that a shortened thermostat or an over current or the thermostat is experiencing too much load. And it's just resetting the time delay we're just going to bypass the thermostat just to try to figure out what the problem is.

So how can we do that? Why not okay go ahead and what what are you going to wire net okay? She said r, g and y, so what is our g call gon na bring on and our white call, and why are we connecting him to red, constant power, so we're going to take a wire nut and we're going to jumper, red, green and yellow and hopefully Figure out, why is our time delay resetting every time it it expires goes across five minutes. It resets try to figure this out. You picked up on something you could hear it so immediately. We don't have our blower running, which it should be we're getting the signal for the blower to run and the condenser is not running and it looks like we have an error code.

What's that fuse okay, the error code. So how can we make sure the the fuse is actually blown oh panels over there? We could either foam it out, so we could either own it out or look at it visually. If you're looking through this fuse you'll be able to see, we have a black mark where it's actually burnt and you can tell it's pop, but let's go ahead and test that with my meter, we're going to find out if we have a path still reading infinite. We don't have any path, so we've blown a fuse moving on to eric's method here, so we're going to use the ohm meter.

So we have it on ohm scale right now, right, you're always going to there. You go exactly always double check, and so now you have to unplug both wires from the transformer, or else you get a false reading right back. We already checked this, so we know power's off way, no power's off exactly yep, so you're gon na so you're pulling the wires off of the secondary, so both you're common and you're hot, and then your way am i checking from i would comment. I would check every wire nut to ground first first, because your commons still bonded to ground the way that that spay terminal is on that transformer yeah.

If you see what he's saying here, the common your your ground and your common are still connected together. So you can just well, you don't have to just touch the ground. Just touch one lead the ground to that point: we're getting potential there. What are you getting as far as yeah? I wouldn't be worried about that.

Okay, so this is another. This is why this is a pro move, because you're noticing now you're measuring the ohms of the load, because you're going through the entire circuit. Now exactly so, what you're looking for is not 14 ohms you're, looking for something much closer to zero, so go through each one and find the one that's much closer to zero on a system like this i'd be most concerned with stuff in single digits, because usually The compressor contactor is the biggest load and it's around 10 to 15. carrier is the sponsor of our podcast and we're very thankful to that really yeah.

Actually, it's really low care, yeah, there's two stage systems. What i want to put in my own okay great, so this is the trick, and this is why i don't i don't love this method for a newer tech. Is that they've got to make sure that they've got really good connection inside each wire. Now i've already mentioned that you could take wire nuts off if need be, if you're not getting in there with your meter, and you don't have to pull wires apart, though you could, like you, just just did there, so that is that is common.

So yes, you're going to get zero there, because that is common all right. So what do we got there? We have 1.2, okay, very low, all right. So what is that? What does that tell us? What's the conclusion that there's there's a short because it's taking a shortcut off of the load that it's designed to go through? Okay, so it's a short in what conductor, though in the uh? What conductor is that green green got it so or g? So now the next thing i would do is i would actually disconnect these from each other and check them individually to ground to figure out. Is it maybe somewhere, you know going back to the blower, or is it actually that conductor? So in this, in this method, we disconnected from the transformer so we're not using voltage we're doing it, de-energized we're using the ohm meter and now we're measuring a low ohm path between g and ground, specifically because on this, transformer g and ground are bonded together.

They're connected together, not g, common and ground are connected together already. Now, that's not always going to be the case, so you have to think through all that, so there's a lot to think through um good way, but now, let's do it my way, which is going to prove the same thing. What are we going to do next? I'll put on the pro short tool, so we don't blow another piece of pieces. So what did we learn from our previous experiment about the fuse blowing? What have we learned from the unit running already? Well, the blower was running earlier without any problems.

So it's going to be why so it's got to be on the hood okay. Why and our time delay is connected to our y call, so it tried to run and it reset, because it it wasn't getting now we could disconnect the wire yep and connect it leave the other two connected and all right. What are we going to need in order for this to work, something a reusable fuse, the pro tool? Where is this yep, so we're going to use the reusable fuse that was out here? So we don't burn through a lot of fuses? Okay, so we don't have a short there right now. What what's the rating on this? Does it say yeah 2.2 amps, so this should pop at 2.2 amps and the one that blew in there before was a three amp fuse yeah.

So now we connected our red to green and it's running, it's not blowing anything yep. So now we'll do the we'll connect red to yellow, probably just be able to touch them together. There's enough room here that you can probably touch them together and see what happens. Yeah, it's immediately dropping out, okay go ahead and our light came on signaling.

There is a blown tube yep, so our light came on signaling us that we had too too much voltage. So we got a short on yellow. So how are we going to find out where this is? Where is our over current on yellow? You start at the condenser yep go ahead open a good short investigation starts with a visual inspection and, if you don't see anything obvious start looking elsewhere. So this is a straight cool.

We don't have a defrost board to worry about. Do we have low voltage, switch it uh, i mean low pressure. Switches looks like we don't so our path goes straight to here we still have power, and then we have our low voltage wire running down along here and back to our board, so it could be anywhere in there right. Why don't? We use the meter to try to isolate where this short might be right, and so can we do that by trying to do wires together, like you said before, and then test it again nope.

So we're not looking to see if we have continuity. We know we have a path already. We just have a path to the wrong spot, which is most likely ground. That's probably the first thing i would check.

So if you were to disconnect your yellow and then take your meter and test between yellow and ground, you should have no path between yellow and ground, so we could own between ground and yellow and find out if we have a short on the ground somewhere by Doing that all right, we'll turn it off. You want to meet up now, yep, so let's go ahead and turn off voltage. We don't want power while we're trying to do this so now plug those back in disconnect all of your wires from each other other than your commons. Everything but congress yep we're leaving the condenser connected as normal yep uh we're no we're just actually.

Okay, since we already know which circuit it is we're just going to do this one just to save time um, so you can leave everything connected other than other than this one. Now we're going to energize put all your wire nuts back on other than your g. Next time you take this out, and then you get this little sticker thing that you can put a zip tie through and you zip tie them right down here - all nice and neat nice and neat yeah. I really don't le.

I don't like that little. This is just the potential: that's how they get their ul rating really because it separates, oh because it's that wires from the yeah yeah. Okay. So now before we energize in this case, because we're - and this is the same kind of test - you do - you know what we call the redneck test on your compressor.

It's like the last test. You do to make sure that that is the circuit, because before it was tripping the breaker right now we're going to go ahead and energize it safety glasses on energize it and see. If now, with g disconnected, does everything else run as expected? Does everything else energize and run because i'm trying to take a shortcut here in order for this to, in order for this to work properly, we have to, we still have to disconnect everything um so, but something interesting is happening here, this finally tripped, but you saw It tried to run a couple times. The thermostat has an overload protector in it, so when it's when it sees too much current, it actually starts resetting and that's actually an issue that we had um with a couple models of thermostats, where it made it hard to diagnose short circuits, because it would actually Just sit there and stay in time delay forever.

It would never come out of time delay. So that's something that you will see in some cases with short circuits where it won't trip the fuse, because it never allows it to stay energized long enough, all right. So now, let's do it the proper way, shut off the breakers. Let's disconnect everything and i'm going to show you the way that i would typically confirm it in one pass for a newer technique.

You have the thermostat doing that on especially on the newer ones. Where you pull the base off the wall, it disconnects the thermostat from all those wires, so you could sit there with jumpers, jumpers yeah. That would be yeah. That would be another way, just making sure yeah just double checking yeah.

I don't want to get shot, make fun of your video, though okay, so now listen most of your systems. Common is going to be tied into ground at the transformer. So if you leave common hooked up on the circuit like it is right now, then you're going to get a path to ground when you check yellow to ground, because it's actually going to travel through your load and back to where it's grounded so you're going to Want to disconnect common yeah during this test, so you can actually see what's going on there yep, so he's got yellow to ground. I would have checked from inside yeah at the air handler that would have been just fine yep check ground that wire you're wired yeah.

Your wax your wiring, that's good, okay, so he's not getting any path. Now, what yellow are you checking? You're checking the yellow going straight to here we're supposed to be checking the wire the low voltage wire, okay, any path there. So, according to the meter, we don't have a pass on our yellow thermostat wire between here and connected all the way back to this unit. Okay and remember what we said about common common is grounded at the transformer, so there should be a path which is why we removed it.

So we wouldn't get confused by that. So if we don't have a short anybody, anybody want to start trying to fill in where this. Where could this be happening? What could be going on transformer? I mean a contactor could be contactor. What would what would the contactor be doing? That would cause a short chatter chattering that that might happen if there's a short or a voltage to draw.

So what is a short? What would we talk about a shorts, an undesigned path, something happening, but what what causes a blown fuse over current? So we got too much current. This one was rated for three amps. If it's not a connection to ground, like say, let's say it was rub out on ground. That would be a path for the current to take without any resistance right.

But if you notice we already checked common is hooked up to ground and the other side's hooked up to yellow. We do have a path back to ground through the component. Why doesn't it blow a fuse? What slows down the current resistance? The coil where's, the coil in within the contactor? Exactly so that coil actually generates a load that creates resistance and it slows down the current that's trying to get to ground. But it slows it down enough that we don't exceed three amps.

We don't pop our fuse. So maybe we have an issue there. Maybe we have an issue with our. We got ta check the home someday yeah.

So let's, let's check the ohms on the contactor. So what to eric's point again - and this just comes down to the irritation of disconnecting wire nuts um - you could do you - could just pull the thermostat off the wall and do it there. So now you're you're jumping each circuit, because what we're trying to find now is which circuit? Which conductor is shorted? Which conductor is tripping the breaker right now. We already know because we test it the other way, but i just want to demonstrate um how this would typically work.

So now we have to do not the common, though common, whenever you're doing this test leave common completely connected and disconnect and yeah disconnect everything else. Uh, no, in that case it doesn't matter, but you have to have you have to have that path connected back one thing to keep in mind too. You may not see a lot around here, but i used to see a lot is in apartment buildings. They would join the condenser to the thermostat and the thermostat to the air handler, so your junction wouldn't necessarily be in the air handler, keep an eye out for that and attack it accordingly, because you'd have to do it.

You'd have to approach it differently, yeah. It is making it into a real rigmarole. Isn't it all right? We good. I left this one on, but i disconnected both slopes.

So now we have our r circuit a red right here and we can just use this one. So we're going to take each conductor. Now and we're going to touch them individually to that in what setting and we're not going to we're not going to use a meter at all. So this is a meterless test at this point now we're now.

What we're doing is we go ahead powering on so common's still connected, so it's still connected to ground everything's connected the circuit's still intact, but now i have 24 volt power right here right or at least i should we can confirm it, go ahead and confirm that From red yep we're just going to confirm, we have 24 volts there. So now we're going to take each one of our circuits and connect to our 24 volt power supply. We've confirmed that we have it and we're going to find, which one blows the fuse yeah just start wherever you want, does it blow the fuse? No, it doesn't so it's not that circuit go ahead and go to green now. It took a second though this is what i don't like about these breakers, because, even though that's a three amp fuse, did you see how long that thing took like these things are notorious for burning up, uh transformers? That's why the smaller, especially the five amp ones, yeah the five amp ones.

I've had all kinds of. So that's why i prefer short pro because it just doesn't. It has high resistance in it, and so that prevents it from causing a problem. It's just basically the light lights up.

This is where things can get tricky jessica. What's the load called through a contactor yeah, the resistive load, it's a different type of load than like a a uh light bulb inductive handler conductive load. Okay, i thought you said 26. No no points all right point so 0.6.

So how much resistance is that? Because ohms is reading resistance right? How many ohms are you reading when you have a path like this, with with no resistance very low, so we got zero? We have almost no resistance across that contactor, probably not. Let's find out, though it looks pretty crispy yeah. It actually was stuck closed, but i don't think the contact is actually was that mine. Let's, let's test this one, another old one, your hand's a little shaky there but yeah.

What is it 10 to 15 yeah yeah? It's a two pulse, probably more like ten yeah, so this one's 14., the load that this produces, is actually generated.