Bryan explains what wide-narrow-wide diagnosis is in the troubleshooting process. He also explains why it’s so effective in the HVAC trade as well as how you can use it to do thorough work and earn good money. This video was taken at an HVAC training event in Birmingham, AL.
When a good diagnostician walks into a home, they look at the problem very broadly or start with a “wide” approach to diagnosis. They don’t limit their scope to a certain component or head to the call with a fixed pre-diagnosis. Good technicians listen to the customer, look for new thermostats, check the filter, and note every detail they can that could be relevant to the system performance.
Once you’ve noted all of the noticeable broad items of interest with the whole system, you can shift your focus to finding the main thing that is keeping the HVAC system from working. Check your static pressure and other diagnostic readings on the airflow side. Weigh the charge as well to see if you might be dealing with a leaky or overcharged system. Even if you don’t find any airflow or charge problems, you can still check those things to rule out possible issues.
Pay attention to line set lengths, missing accessories (e.g., crankcase heaters), and start gear (capacitors) as well. Check everything you can before you run test the compressor. Being thorough is the key, and most good companies should allow you to be as thorough as you need to get a proper diagnosis. (However, that requires a balance of thoughtfulness and efficiency, and you need to charge an appropriate amount of money for good work.)
Read all the tech tips, take the quizzes, and find our handy calculators at https://www.hvacrschool.com/.
When a good diagnostician walks into a home, they look at the problem very broadly or start with a “wide” approach to diagnosis. They don’t limit their scope to a certain component or head to the call with a fixed pre-diagnosis. Good technicians listen to the customer, look for new thermostats, check the filter, and note every detail they can that could be relevant to the system performance.
Once you’ve noted all of the noticeable broad items of interest with the whole system, you can shift your focus to finding the main thing that is keeping the HVAC system from working. Check your static pressure and other diagnostic readings on the airflow side. Weigh the charge as well to see if you might be dealing with a leaky or overcharged system. Even if you don’t find any airflow or charge problems, you can still check those things to rule out possible issues.
Pay attention to line set lengths, missing accessories (e.g., crankcase heaters), and start gear (capacitors) as well. Check everything you can before you run test the compressor. Being thorough is the key, and most good companies should allow you to be as thorough as you need to get a proper diagnosis. (However, that requires a balance of thoughtfulness and efficiency, and you need to charge an appropriate amount of money for good work.)
Read all the tech tips, take the quizzes, and find our handy calculators at https://www.hvacrschool.com/.
So if there's one thing that i could teach somebody, that's like here's, a concept for a troubleshooter for somebody, who's a technician. Now, people skills - you know, integrity, work, ethic. Those are things that are more important, but i'm not going to teach most people that you either pretty we're taught that by your parents or you're, probably going to have a hard time in life, but in terms of a technician. This is the concept that i want to teach people start wide, go narrow, then go wide again when a really good technician goes into a house.
The first thing they do is they start really wide. They don't jump into. Oh, i bet it's like a pastor. I used to have this guy.
His name is jimmy who i would ride with and uh. He would guess what was going to be wrong with the next job before we got there, it was his favorite thing to do. I bet you this one's going to be whatever, and i bet you you know could guess that in many cases it was the thing that he guessed, even though it wasn't the thing that he guessed. If you know what i'm saying so, you want to go in with an open and very wide mind, and the first thing is to listen to the customer.
Actually, before you even listen to the customer you're listening to the equipment when you're walking up how many times when you walk up to a house, well, you notice the oh connection, fans running, but it's real quiet, sure enough! Compressors not running could be failed run. Cap could be a lot of things right. Probably a field run gap because that's what it seems to be a lot but you're paying attention as you go and then you go in and you talk to the customer. So maybe it is that failed run cat.
Maybe it is the backed up drain could be, i think, your market's probably like ours. We probably have a ton of backed up drains when it's humid humid markets really struggle with that, but you go and you talk to a customer. So what's it been doing you're? Looking at the thermostat you're paying attention hey, you know what that thermos. They got a new nest thermostat on the wall huh.
I wasn't here last time or whatever uh yeah, so the customer yeah, whatever uh, when did when did the? When did you get the new thermostat, the nice new thermostat here, oh yeah, my husband put that in three weeks ago he blew the fuse, but he figured it out. He put a new one in oh we're going to check that fuse. You know you're paying attention to all those things chris stevens, i don't know if any of you follow chris stevens hvcr videos. He talks about big picture being really big picture about things.
That's where you start, but once your big picture once you've gone through and you've paid attention, i'm not saying you know check the you know, i'm not saying not to check the filter check it now's the time to check it check the underside of that evaporator coil. If you can get to it, look at the condenser coil condition. Look for wire! Rub outs, pay attention to the entire thing. Look at the install practices! You guys work on a lot of furnaces here, venting pay attention to that water heater. Does it look like that? Sucker's been back drafting you got that you know that hood on the bottom. It's all it's got a bunch of corrosion on it, pay attention to that, you might save somebody's life or maybe not save their life. We keep them from getting sick. You know maybe they've been having headaches for years.
You know, heaven forbid. I've been i've been very sleepy. Lately yeah, i bet you have you're just paying attention to all that stuff and then you go narrow. Now you find the problem.
You've already looked at all the possibilities of everything around it. Now you find the thing: that's keeping that piece of equipment from not working and that's where a lot of you know a lot of people who are good at process. People good maintenance, folks. They really struggle with this part and they would do really well from focusing on the rest of the stuff.
We talked about understand the refrigerant circuit. Understand the airflow side understand the electrical side once you figure that out now find the cause. Now, here's here's a trick. Question because this is something i'd, love to see more people do say you go to a system and it's four years old and you didn't install it.
I'm just painting a picture here. It's not that this matters so much it's four years old. You didn't install it. You show up you test it and it's got a grounded compressor.
None of this is outside of the realm of possibility. This is the sort of call we run into all the time. What else do you check? So you know it's grounded you've done the redneck test. It's it's it's! It's not! You know it's it's bad.
We got a grounded, compressor right, you didn't just use the supco thing and mash the button and it said bad. You know that it has failed. You did your good diagnostician, you know. So what do you do to back back out again and go wide again before you leave? You can't test the thing until you get the compressor in it.
Pay attention to airflow pay attention. I would go through i'd, go ahead and check your static pressure right now. You're not going it's not going to be exactly right because you don't have a wet coil, but you know you can get a pretty good sense. Hey if you've got a true flow grid, use that sucker that'd be great.
You know you're going to get a really good you're going to know exactly what your flow is. Look at your return size, look at your supply size, yeah, pay attention to the things that look like the customer. Just did the piece of equipment like like a new air filter. That's a good one! Here's an interesting one! Why don't we when we're there? Let's say the system is seven years old, eight years old, why don't we go ahead and weigh out the charge? Now? Does anybody ever do that ever thought about doing that? Why don't we now? This is assuming that you are coming back and doing the job. This is once you know that you're doing the job right, but why don't we do that? Because you got to pull the charge out anyway right it's coming out. Why don't we weigh it out because we would know something pretty. We would know some pretty interesting things about that system if we waited out what if we waited out and the system charge on the data plate was six pounds and we weigh out 12.. Do you think that doesn't happen? It happens all the time i had one.
The other day i have a young installer, great guy, an amazing young man, went to a system. He was having a heck of a time with it is having all kinds of issues and we went out on a duckling system that he installed and we weighed 21 pounds of our 410a out of that system, and i said aaron like what what was going on There he's like well it just kept going in the pressures weren't where they were supposed to be. I'm like that's not how that works. Like we've.
We've had this conversation, but trust me from now on. He uses a scale, i'm like hey. If you go in - and you know like you've, looked at the line set length and all that and you put more than a couple ounces more than this on that chart and your pressure still ain't, where they're supposed to be go ahead and stop. You know if you've got a system, that's got way too much charge in it.
There's a very good chance. That system has a restriction, a metering device issue or likely an airflow problem, because somebody was putting refrigerant in there. Why? Because my pressures ain't, where they're supposed to be - and what do they specifically mean by that my suction pressure isn't high enough? That's what they mean because they learn very early on that. If you don't get your suction pressure high enough, what happens? The evaporator coil freezes up, and that is very inconvenient because the customer notices that - and you got to keep going back right, so you get your suction pressure up where it's supposed to be so that way you can go home, but that's not how that works.
Obviously, so that's one thing: what if what if it's a system, that's supposed to hold five pounds or six pounds on the data tag and we've only pulled two pounds out of it: okay, could that cause a compressor failure yep both of those things low, airflow overcharged? Can those cause a compressor failure? Yep can undercharge causing pressure failure. Yep. Wouldn't it be nice to know if you have an evap coil leak. Now then later, when you go back and you try to pull the vacuum and it's not pulling down and then you just send it and then you have to go back three weeks later, this sort of stuff happens all the time, and it's also you know this Is a time saving thing you can do right now, a technician you're, the troubleshooting tech customer confirmed.
You ever need a compressor. It's warranty whatever all right, i'm gon na go and pull the charge out now, just make sure it is okay, it's right where it should be. I've eliminated that i've looked at airflow. I paid attention to that. All right we're going to go ahead and replace the start gear 2.. Now, if you're in commercial, that would mean always replacing the contactor as well, because single phasing is such a problem in commercial and residential. Do i care, if you replace the contactor or not? I don't care that much it's cheap as long as you wire it right, i'm fine with it. I actually worry sometimes about putting a new contactor in because you know might put a tuple in place of a oneplus and now you're uh.
Now your crankcase is not working or whatever you know, so it kind of kind of concerns me a little bit, but you know if you want to make sure you know, make sure you're putting in the right capacitor. That goes with the new compressor because it isn't always the same. That's another thing to watch for so putting in new start gear, you're paying attention. Oh hey! This has got an 80 foot line set.
This falls under the long line guidelines. Let's look that up. Oh, this system is supposed to have a crankcase heater and it doesn't have one could that cause the compressor to fail sure you get what i'm saying. How often do we take it to this nth degree to make sure that this compressor is not going to fail with all the things we can do before we even fire it on the first time before we wire it up and fire it up.
I just like to say that as much as i can, because my favorite line wire up and fire it up before we do that we do everything we can and then you run test it. Not the old. Well, i'm gon na have to run test it before. I can see if anything else is wrong.
There's a lot of things you can do before to see. If anything else is wrong before you start to run test it, and my encouragement is just do it - we get in this mindset where, let's say some version of well, my boss isn't going to put up with that. Your boss is probably a decent person who he's not okay, all right, i'm not going to tell him. You said that geez, your boss is probably, i said, probably a decent person.
Who's probably been kicked in the teeth by life, like many of us, have who's, probably trying to figure out how to make a profit and who's, probably struggling unless you work for one of these, you know white shirt companies where you get the american flag patch on The arm and your whole job is to sell, which i doubt it's any of you here, because why would you be coming to my class because you don't listen to my podcast? If that's the case, unless you're spying, are you the spy tony you kind of look like a spy, and by that i mean you, look a little too good. That's what i was going for there just just saying: okay, all right, if that's the case, you're working for somebody who cares about getting it right, then they're going to learn pretty quickly that you're reducing callbacks you're, reducing issues by being thorough. What i'm not saying is be the old-time technician who gets so grouchy and so beat up that you're dragging everywhere. You go you're saying i just i just work smarter, not harder. Here we go, i'm going to get there someday and i it's not what i'm saying, because you we've all known that guy too who's actually got a good mind um, but who has kind of given up the whole thing, and so that's that's not it, but you're Being efficient with your time, you're, not breaking your back you're just being thoughtful and saying we're going to make sure that we're going to prevent all these problems and we're going to charge along the way. Because that's the other side of all of this, when you talk about being this level of thorough, you got to charge for what you do, you shouldn't be the cheapest if you are the cheapest, why are you doing that? You shouldn't be in this room carrying as much clearly as you do to be here on a friday and not be like charging good money. Your doctor makes good money. Your dentist makes good money.
The lawyer makes good money. All those people make good money. You should be making good money not because you're selling everybody a piece of equipment and not because you're slapping a indoor quality product in every house and not because you're selling a maintenance contract in every job you go to. Although it's fine in some cases, if you're doing those things where appropriate, it's, you should make good money, because you're good at your job and you're doing the stuff we're talking about here and those are the types of if you work for currently work for a company That doesn't buy some of the stuff that i'm saying i'm not saying they have to buy all of it, because i could be wrong about some of it.
I might be telling you some stupid stuff. You know bert tells me all the time the stuff i come up with is stupid and he's probably right, but he's also a little stupid too. You all know that if you've seen the videos - but you know being thorough like this - was just gon na save everybody a lot of money - it's gon na make for happy customers thanks for watching our video. If you enjoyed it and got something out of it.
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Is there a place to watch this complete presentation??
Thank you for the videos. Very very helpful
This is great info for guys just starting and a great reminder for the seasoned guys. Complacency can cause numerous issues including death and 9/10 times the customer will point you in the right direction. They may not know a system like we do but they do know something has changed.
So much wisdom and experience of what is right in such a short amount of time.