Trevor thanks for joining us again on the hvac school podcast. Thank you so much for having me brian should i refer to you from now on as um mr refrigeration mentor, or something like that or yeah. If you wanted yeah, yes, i got a good ring coming from you yeah it is yeah the the refrigeration mentor uh yeah. So so trevor is now officially the ceo founder president chief magnate of uh refrigerationmentor.com and the site is up.

I just took a look at it: it's very nice, really slick um, there's some good podcasts up there. So i was glad to see that you know some good quality podcasts uh on on the page, uh yes and uh yeah. So it's it's a great site and obviously trevor's doing a lot of mentorship and training in the refrigeration space. We talked about that in a recent episode, but now we're back to the specifics.

So today we're going to be covering uh ae bulletin 1433 and just give us a quick overview of what that uh. What that covers, what 1433 is all about, so we're going to be talking about um cs compressors, so these are hermetic reciprocating, compressors and they're, starting to run on some of these newer refrigerants, like four four eight, four, four nine and high glide refrigerants - and i wanted To go through this because i think it's very important what is going on in these bulletins, not only in emerson's bulletins, they do a great job, laying them out as well as other manufacturers boltons. You need to check and find these compressor manuals, and i thought this was a great one to bring to the podcast to talk about today. Awesome yeah, so uh, specifically this cs compressor.

What type of technology is this? What's the what's the application, so you're gon na see it in applications. Smaller tonnage, probably you know between it, says one to seven horsepower right there in the designations so you'll be looking up to. You know how many thousands btu, depending on what temperature it is, but up to 70 80 000 btus for medium temp, maybe um 50. Some thousand btus for low temp i'd have to check that in either copela mobile or pss software, where you'll get even more information involved and uh you'll see that they'll do uh, high-tech medium temp extended medium temp ranges got it, but this is a you know.

So small-ish um reciprocating, uh, hermetic compressor, so you're not going to not going to open this bad boy yep you got pistons inside, but very common. I mean this is a. This is a very common compressor that you'll see on a lot of different equipment, and it makes it a great topic to kind of cover here, because there is some variability. I mean it's not.

These are not exactly the same as scrolls. We talk so much about scrolls, but these actually have some some differences here and right off the bat uh. It discusses um some some limitations, some operating envelope thing. So you want to start by talking about that yeah.

So right off the bat it talks about one that says approved operation envelopes for figure four and figure eight. So, that's something that you need to go and look at the operation envelope of the compressors, because you want to make sure that you don't run outside those envelopes when you start doing it with any compressor. It starts to cause um damage, so you'll see some of them there on page 16, 15, where that's the operating envelope. That compressor with r22, for example, can go from zero.

I'm just looking at brian's screen up to 30 degrees fahrenheit and then it can go from 90, condensing all the way up to 140, and this is for r22 in that right box. It says: 65 degrees, return gas. If you're, that's what you want to maintain. That's between 10, like i guess 11 degrees - fahrenheit all the way up to 30 degrees fahrenheit.

But if you look at that blue area say you want to run it at 110 and 5 degrees, 110, condensing 5 degrees evaporator. You need to have a maximum of 40 degrees because that that suction line definitely needs to be insulated and we all in refrigeration are. They should be insulated anyway, in any application in their condition, they should be insulated, but maximum 40 degrees. If not just say you run out that 65 degrees you're, probably going to be overheating, that compressor that's kind of what those blue areas mean exactly and just you know when we say return, gas, temperature or rg here we're talking about our suction line temperature.

We're talking about what is the suction line temperature right before it enters that compressor, um, so right off the bat we've got some really interesting and very practical numbers that we're looking to hit here. We can see, you know 65 degree return gas temperature, that's sort of the the you know the standard um kind of maximum uh. But then, if we're going to run a little little lower return gas temperature, then maybe we can run it in a little wider envelope and that's going to change depending on the refrigerant as well. So that was just foreign when we get down lower.

We look at four four, eight, four, four, nine 404, 507a and f, it's going to be a bit different, but so this is something you need to be aware of. So when you're you're checking that return gas tamper, you should always be doing this when you're doing troubleshooting and services always checking that temperature. So if we look on these compressors are approved to operate down to 70 degrees fahrenheit, and we just seen with our 22 was only 90. So it depends on the refrigerant again that discharge line temperature 225 and 107c.

I kind of like the way emerson is starting to add new things to their bulletins, just to help technicians understand the difference between fahrenheit and celsius, because, i think that's something units are very important as a technician to learn, because you never know what type of equipment You're going to be working on, it could come and bar, especially all these newer equipment coming from your propane co2 systems. Uh. It's good to understand that, and it's always good to learn more what the discharge valve backer 275 means. So on that valve plate there is you're going to have your valves and then there's something that you'll see.

I don't have a valve plate here to show. I wish i did there's a backer, so it doesn't really break off that discharge valve so it'll, stop it from um breaking or bending, and that's this looking. You don't want to go over 275 and then the oil sump, 200 and mortar wine is 275, and so these are tests that copeland have done and made sure that it runs in these conditions, um to verify that their compressors are going to work. For a long time and and in good standing, if i'm understanding this correctly, what what they're saying here is is that this is how they decided on the envelopes, so they decided on the envelopes in order to make sure that they stayed below these temperatures at these Different points in the compressor is that is that correct, that's exactly right and if you're, not, if you read the next sentence there, if the system cannot be guaranteeing those guidelines, you need to have a discharge line, thermostat six inches away set for 250 on these ones.

To protect that compressor, because if you're not keeping those temperatures, you're going to be overheating, that compressor yeah so and so it's interesting that they give you the envelope and then they even just you know they give you a little bit of. I don't want to say wiggle room, but they say, but if you can't now then do this, which is you know it's nice, i mean because they recognize not everything's gon na be perfect yeah, and i like that too, because it it gives a safety for your Customer right, i really believe in systems, especially larger systems expenses, and should have these extra safeties yeah. Oh well, we're looking at costs and stuff, but cost doesn't mean anything if it fails in six months. There's a lot of costs for everyone that that end.

So so next is super heat. Once again, we talked about this many times it doesn't matter if it's semi-hermetic, if it's hermetic, if it's a scroll, whatever compressor 20 degree supreme, you know that's what we're kind of looking for um, depending on the application we're seeing and i'm sorry, i'm seeing more with The new refrigerants, like r513 they're, saying it's mandatory to have 20 degrees superheat. If you look at a lot of the compressor manufacturers. The way the this refrigerant is made up that there's potential to dilute before you even hit that zero degree superheat.

So they're saying on certain refrigerant, newer, refrigerant, blended refrigerant that you have to make sure you have a super heat, a minimum superheat, so something to be aware of, but new, refrigerants yeah. So because, in the past, when we had um, you know kind of our old school, r22s and r12s, and all that we would say: okay, you're, not gon na have dilution until you hit zero superheat until you get a truly flooded condition. But now, when you have blends - and you know the refrigerants just aren't that aren't as simple as they used to be - we definitely have to ensure this, and so again i want to remind everybody when we say 20 degrees, fahrenheit superheat. In this context, we're talking about compressor, superheat, we're talking about superheat right before it enters the compressor six inches from the suction valve.

We're not talking about evaporator superheat, because you may have 10 degrees of evaporator superheat, but you're still in order to get 20 degrees superheat at the compressor, then you would have to pick up an additional 10. um. If you, if you're not getting that so say you have very short, coupled um sort of configuration, then you would need to you know, crank up your evaporator superheat in order to make sure that you're in that safe zone at 20 degrees superheat at your compressor. Because that's a it's a protection, you don't want it to be significantly higher than that at the compressor, because it can overheat and you don't want it to be uh significantly lower than that, because you can get oil, dilution yeah and that's what we see in the Super market or sorry co2 systems where they have to add a heat exchanger in the suction line, to bring that superheat up to make sure that you don't go below say 20 degrees or 36 degrees fahrenheit.

So i'm sure we're going to see something like that. Some sort of designs to help protect systems down the road we get down to 0.5 suction accumulator. They recommend having a suction accumulator, especially if you have over 6 pound charge in it in the system and then on systems with defrost harvest during tran uh transient operation. They recommend uh having an accumulator unless you have a suction header that can suffice that volume to prevent any liquid migration.

So it's important to understand this is more on the design side, so this will be for the manufacturers who's using these compressors. But it's also so good as a technician to understand this, because we know as technicians not all equipment works as in the lab as it should as in the field right. So it's something to review and check yeah and also it's good to understand why some systems have an accumulator and why some don't? Why some don't right, i mean that's a question that people ask: why does this unit have one? And why doesn't this one happen because they behave differently? I mean we. We talk about this a lot when you're charging a system that has an accumulator, especially if you're feeding you know, liquid into the suction line in real small amounts.

Kind of you know feeding in real slowly, which is the standard way we charge systems while they're running recognizing that that refrigerant's going into the accumulator - and it doesn't make it out into the system as quickly because it's metered through the accumulator. We did a video where we, you know we're, showing people how to charge, and we realized pretty quickly that we were overcharging the system because we weren't being patient and doing our video um. So so, literally just understanding, you know what you've got in the system and why it's there is is really critical, and in this case it explains it. You know when you have more refrigerant, that's a case where you have more likelihood that you're going to have um.

You know flood back you're, going to have more likely higher likelihood of of off cycle migration um when you have higher refrigerant charges, so um. So, just understanding that i think is is very useful for the tech yeah exactly get down to point six there, liquid line check valve so it says um with compressors, with greater than six pounds check valve is required between the receiver and the condenser, something to something That you wouldn't really think of you know when you're installing a system to see is there a check valve in there or not right, and it says this will reduce liquid refrigerant migration to the compressor during transport and storage. Also down below there. It says energize that crankcase here four hours before initial startup yeah, that's one.

That's one. That's been on specs for a long time and i think people have ignored it. But in many cases, especially when you're setting up a new piece of equipment, you could actually go ahead and get that thing powered up, get it running for a while before you um before you start running it. It really is a good practice uh in order to just prevent initially running that compressor with liquid refrigerant still on the crankcase yeah that exactly exactly point seven crankcase heaters, i any outdoor system.

I say you should have a crankcase heater uh any time and then it says even indoor applications below 40f have a crank case seater in there and required on any system with accumulator, because just like you just said there, brian, that accumulator has a bunch of refrigerant. The system shuts off you know, even if it has a pump down cycle in it, there's still refrigerant in that accumulator. If that compressor is colder than the accumulator where's that refrigerant going to go, travel right, so something to be aware of yeah and this references. Ae22.

1182 about liquid refrigerant control that that's a really good, um, really good bulletin to review, and we've talked about that one in the past. Okay, well pump down recommendation, so if short cycle occurs, please check these factors, and this is important. This is like for any pump down system. You need to check this.

If you have short cycling issues, it is you need to correct that problem. You do not let it go start it 75 times in an hour, because every time that starts up that compressor shoots out some oil it shoots out. The oil pop-out rate is really high on startups. So you need to understand that that system needs to run.

For some time to get that oil back right, so it says right here: low pressure sensor, if located right at the inlet of the compressor, will be more sensitive to pressure. Spikes, for that you know, may cause short cycles, so you got to think of that. Maybe it has to be moved well, it's been there since it was installed well just because it was in there since it's installed doesn't mean it was done correct in the first place right. So it's something you need to think outside the box.

Sometimes you need to check your low pressure setting. You need to understand that encapsulate. Non-Adjustable types are more susceptible for short cycling due to tolerance, and then, if you cannot stop that short cyclin happening, they recommend adding a five minute time delay and i've done that before. In the field - and i know many - other people have two, because you need to stop the short cycle because you'll run into uh lubrication issues yeah, one of the biggest things you see is here talks about the actual low pressure setting and number two here you see A lot in refrigeration people setting up the low pressure setting and pump down just way too low um.

They don't need to pump down uh as low as a lot of times people people set them up for and that you know that alone can cause more short. Cycling, so if you just want to click on table three, there it'll take you right down to the table and in the table it says: minimum recommended low pressure, control settings and then down below note, based on five f outside the lowest point. They have uh in the evaporator uh envelope, sorry at sea level, so that means they're, saying this: you set it to for 449 13 psig. That is outside the envelope of the compressor.

So you need to understand that too say because you say oh well, 13 is the lowest. You can go well, they're saying you can go 5 out so because the lowest for 448 is actually 16 psi. I checked it. That's the envelope, but with low pressure controls for when you're doing, pump down or shut off or safety, you can go outside the envelope for a short period of time.

You just don't want to run and run and run and run and run outside the envelope or short cycle outside, or do this all the time short cycling on and off yeah 100, and that's where you you can run into major issues with compressors uh have an Issue like failing uh there's a warning there look poe may cause allergic skin reaction. Everyone people, please use gloves eye protection. I've i've got stuff in my eyes, cut my hands oil in the face before and it's not fun. I have allergic reactions from it from it.

Right so it's you need to be safe out there, your eyes, your ears, your senses. You need to go home to your family and i always read the warnings, because i see a lot of people. They just skip the warnings uh and i used to too don't get me wrong. I used to skip them too, but it's important yeah.

We just had it happen. The other day we had somebody uh who was brazing and they didn't they weren't wearing their safety glasses and they somehow got a a brazing rod stuck in their eye. You know it's like that. Sort of stuff is awful and it's so easily prevented.

I mean, i understand a lot of people. You know you get busy if you forget, but you really have to prioritize uh, ppe and paying attention to this sort of stuff, because all it takes is one little slip up and you can potentially lose your sight or you know even worse, yeah and and that's So important you want to go to your family at the home, to your family at the end of the day, just be safe, take a little longer in the job. Don't worry what your service manager says or what your boss says. They want you to be safe.

As well, yes, they want their job done quickly, but if you're hurt and you're off for two weeks, you can't you're not out there working either. So they want you to work safe as well um as we go down just in the lower part there. It says compressor: recharge is four ounces, less than or initial charge. So when you look on copper, mobile, you'll see uh initial charge and then recharge.

That means that's the service replacement compressor always has less oil, so bill of materials like with 800 at the end for semi-hermetics, they will have less oil scroll, compressors um. When you go to your wholesaler, your supply house they're going to have less oil in it, because, if you're, replacing the compressor, there's oil in the evaporator and the condenser and the accumulator, so there's a reduced charge in those. That's actually that's something i had never heard before, and i've got that question in the past and of course, that just proves that i haven't read the bulletins as carefully as i should, but that makes perfect sense, uh and and actually is quite uh, quite thoughtful and Quite interesting so yeah, if the equipment already has oil out in the system, then that manufacturer, when they ship that replacement compressor, is gon na ship it with slightly less oil than they would for the oem application, which is kind of kind of brilliant yeah. And so practical consideration - i i haven't read this one before, but i thought it was pretty cool and we should talk about it like application restriction imposed on these models may require careful design.

So if you look at the first thing, you uh units operating at low evaporated temperature will be susceptible to overheat, with dirty, condensers and or restricted airflow. Well, we understand that, but with these these compressors it'll be even more um system. Airflow across compressor and condensers should be designed to maintain a discharge line temperature below 250., so they want that airflow to go across that that's so important. This is called.

You know, you're cooling, that compressor with that air and those condensing units. So it blows that air over it you'll see it time and time again, very important that you have that air circulating over there yeah they're, making a really good point here, which is that you may have a piece of equipment that's operating within the envelope when it's Brand new, but when you're running a lower evaporator temperature and you get a dirty condenser, what happens to your compression ratio? Well, it increases right and it increases more quickly when you have a smaller condenser, so they're kind of suggesting here, based on the sound of it that in the design, considerations consider putting in a larger condenser. So that way, you are less susceptible to um to issues as soon as that condenser starts to foul as well. Exactly exactly good good pick up there, brian uh traditional superheat settings txt may be too high to maintain return gas temperatures.

Well, we talked about that return that suction gas coming back. If you're in that you know, we said minus five, i think in 90 you need to have maximum of 40, so you may have to adjust that tx valve you. Never you never want to adjust the tx valve to um, really maintain the compressor superheat. The whole point of that is to maintain that evaporator.

So if the design is wrong and you have to increase that tx valve you there's something else going on with the system, you need to check suction line sizing liquid whatever it is, you need a check. Maybe it's the airflow across the that coil, i'm not sure but uh. If you're trying to adjust that compressor super heat and the tx file with the txl there's something there's something wrong yeah, so you need to think about it, and maybe even maybe there was even supposed to be a design for um. You know liquid to suction heat transfer or something like that in order to get that up, you know there's some other ways that you can potentially potentially do this in order to keep that compressor, superheat and the evaporator superheat, where you want another thing to keep in Mind is is that you can only adjust your your tx valve so low.

I mean we talked about this. You know kind of minimum stable, superheat, um, and so, if you're, in a place where you, maybe you need to squeeze a couple more degrees, lower superheat out of it, you may need to go to an electronic valve in order to accomplish that um or maybe a Slightly different tx valve design, so again that's kind of maybe a little unrealistic or maybe outside of what you'd normally do as a service technician, but just keep in mind that you can only adjust valves so low before they lose control. And you start to slam in and out of zero superheat, which then causes flooding so be careful with that massive hunting and that's a that's a tip too, like you just said there. If you get a lot of hunting, increase your superheat by one degree on your tx valve until it's to stabilize that and um point four uh or sorry point: three insulate your suction line.

That's a minimum yeah! You need to do that. All the time suction to liquid heat exchanger, like you just mentioned brian good job, uh, minimum suction line pressure drop. This is so important. A lot of people don't think about pressure drop, but if you're getting 12 degree 12 psi pressure drop from the evaporator to the compressor.

There's something going on. With that suction line, you need to figure that out. Is there a filter, dryer plugged? An accumulator issue is the suction line, size improperly in the first place, because when you get that pressure drop like that, that compression ratio is skyrocketed and you're going to fail, the compressor quickly anything to keep our suction pressure as stable as possible. No pressure drop is is ideal.

We talked about this with um suction line dryers. How important it is to have minimum pressure drops across those or minimal pressure drops across those same thing is true of your suction line. There's no! Nothing good comes of having a suction line. Pressure drop that isn't there for a reason and uh really.

The only one that that is a reason is is a suction line, filter, dryer and even that should be kept to a bare minimum yeah and i say uh remove that. I know it's not practical all the time, but you'll you'll see in this guy. It probably says 48 or 72 hours after run time, it should be removed. There's no difference with all the manufacturers.

Sportline says that danfoss says it um, as well as here's emerson says as well. They really should be removed, especially if you get any type of pressure drop across. I did see older ae bulletins where it says if it's a permanent install. You can have a three psi depending on the refrigerant and application, but that's three psi massive on that compression ratio.

Yeah, it's still costing you it's costing you in efficiency, it's costing you in compressor longevity by having that pressure drop. So you really wan na again when you're talking about sizing suction lines. Sometimes you have to accept some pressure drop in order to have proper return velocity. You know so there's a balance there.

It's not like you can just infinitely oversize your suction lines, um, but but it should be minimal. I mean it should be almost immeasurable in most applications um. Unless you have like a super super long situation. Um, it's not going to be significant or shouldn't be yeah, and that's something that you should understand is line sizing.

I know day daily or doing service. You don't have to size stuff, but i was having a conversation with a manufacturer last week and he was like he was telling me that um one of the engineers at a company said: okay. Well, i got a 5 8 liquid line going out to the this 1000 btu case, and it's not feeding what's going on. It should be enough liquid at 5 8..

Well, really, it probably should have been a quarter inch line going out to that case, not a 5 8. You know so because you need to think of that velocity. So i would highly recommend doing a little bit of research if you have never sized before. Just to get a better understanding of it yeah you do not want excessive refrigerant in the system.

That's that's a huge thing when people are sizing liquid lines as well. It's like in order to fill that liquid line you have to massively you know, add so much extra refrigerant, which now becomes an issue in the off cycle um. So, there's just lots of reasons why, when line sizing matters - and just you know, don't uh don't pass over that and think that it's not your job as a service technician. When you find something out of the ordinary, because we do as text, we find things that are out of the ordinary and just like we, you know just like we always hear.

If you see something say something exactly or read something. If you see something read something more likely: yeah yeah, no, that's a really good one get into deep vacuum operation here! Well, we know! Well, we should know that you do not want to start a compressor in a deep back. It's going to arc inside a high chance of it. I've seen this time many times cutting open these compressors as well as you want to have a low pressure control on there to prevent you'll, see low pressure control is required to protect against deep vacuum operations.

So what happens if your com, your system, has a leak, and you don't have a low pressure control that compressor is going to just run and run and run and run and run and over time, as all that refrigerant gets out now we start re, reducing uh. It starts to pull that compressor into a vacuum which now we have no insulation, because refrigerant would have been in insulation, and now we get a short and then you'll see a short, usually right at the fuse eye, the pins that are coming through the compressor. That's okay, compressor, cyclin maximum 12 cycles per hour, they'd like to see recommended off time between cycles of 10 seconds minimum. The recommended run time from startup shut to shutdown is five minutes.

It's good good to know. We talked about short cycling already yeah, that's great, and i love that they give these specific numbers, because you know the question will come up well, how much is too much right? Well here it is this. Is this tells you exactly how much is too much, and that doesn't mean that you may not want to even do better than this, but you know if you're, if you're, outside of this sort of you know short cycle envelope, this is a form of an envelope Too right we don't we want, we want to make sure we don't have more than 12 cycles and uh. We want our cycles to be 10 seconds minimum and run time to be uh five minutes.

So, if we're not operating within that, then it needs to be addressed. Yeah exactly and that's what i like about these uh these manuals. They really give you an idea on what to do right. Yep um cycle rate, so we talked about this already cycle rate, also contributes to oil log and, like i said, if you continue to have short cycling, you can have oil log in, but here it says each time the compressor starts.

There's a quick reduction in suction pressure and therefore crankcase pressure. The pressure drop causes a reduction in saturating temperature resulting in oil, refrigerant mixture, flashing into foam and vapor with the frequency results that the large percentage of the crankcase oil is pumped out of the compressor. So because that happens that that quick reject reduction in pressure on that startup that oil mixture refrigerant mixture pumps out even more so and you see you can have higher pump out rates and if this is happening, a lot you're going to get more oil. Out of that compressor quicker, which is going to cause uh oil issues right there, 13 too, and are you going to use this stuff every day? No, but the thing is, you can probably use what i've been noticing about.

Learning about compressors doesn't matter if it's semi-hermetic, scroll or hermetic. There is a lot of similarities and it doesn't matter what manufacturer it is. You can look at all the big manufacturers there's so many similarities. If you look at discharge temperatures similar, if you look at return gas temperature, it's similar with those refrigerants right.

So when you start getting into the habit of reading these looking them up, it's going to make your job so much easier, yup for sure starting como components. Heavy duty type one like they're, telling you exactly the type of starting components, because you can go and buy a star cap, that's uh low duty. They recommend high duty, have a bleed resistor across there to extend the life of the relay. So what happens? If you cut out that uh resistor or if you you put a start, um capacitor in with no bleed resistor, what happens you get sticking relays, which is a major problem? I mean sticking.

A sticking potential relay is a major problem because that results in your start, capacitor staying in the circuit, which is going to result in either compressor, winding failure, start capacitor failure or or both um. So that's the that's. The reason why you're gon na, if you don't have that resistor you're gon na get these arcs every time and those arcs are gon na eventually lead to contact sticking, yeah and uh. I think there are like 15 k, ohms 2 watt, resistor, something that you can have in your truck.

I uh, i didn't always have a heat gun on me when i was in the field, but it's something that over time i work on a lot of electronics. Now because i work at stuff at home, so i use a heat gun they're not hard to to use and put on there if you needed to good old soldering iron, yeah yeah, sorry, i said he couldn't yes, it's a long day already insulated terminal connectors to Be within the compressor terminal box, you'll see them on the right side. There, the molar plug connectors, uh motor protection, internal line, brake motor protector is provided in the single phase, and this opens a common connection to single phase motor at the center of the y connection of the three phase motor. So this is something important to know.

So if that internal overload opens that, that means your your commons open yeah and in the case of three-phase that means you're going to measure open to all three terminals. If it's single-phase. That means that you're going to read open from start to common and run to common, but you will read the designed. I mean as long as it's working properly the designed resistance or ohm measurement between run and start um.

So that tells you right there. When you have that uh kind of when you're taking those measurements, you know that it's a thermal overload a motor protector, that's open and not a winding issue, a hundred percent. That's a really good point! You! You should say that again, one more time, brian, because it's okay, all right yeah, so three phase, it breaks all three. So when you have an open motor protection or overload on three phase breaks all three, so you're not going to measure you're gon na measure, infinite ohms.

When we say when we're saying ohms, we got ta, we got ta distinguish between infinite uh or open uh and and closed or zero ohms, and so you're going to read, infinite or open in between all three so fairly obvious. But if it's single phase you're going to still measure when you have an open motor protector between start and run whatever the design resistance is so you know you can look at the copa mobile app and it will tell you what the difference resistance, what the different Design resistances are between the terminals, and so that's what it will be as long as the compressor is working properly within that tolerance. But you will read an open between common and run and common and start because common is not a winding on a single phase motor. It is just a common connection between start and run and right behind that common terminal is where they locate that thermal overload or motor protector, and so when that opens, that's how you can you know or when you measure it in this way, that's how you can Ensure that you know that it is an open internal overload and not an open, winding yeah perfect, because that i've seen so many in my in my time when i was with copeland come back and they would just start up and and we see it was overheating.

The compressor inside, but for sure they checked that and was open at the time, didn't let it cool down and - and it came back so - and this happens with a lot of single phase - compressors uh internal pressure, relief valve 450 to 550 psi. And when this happens, it results in increased compressor, current and uh protector ambient, which trips off that overload opens the protector high pod tests or mega home tests. You can check out ae 4. 12.

94. It's uh! Once again, i know we've talked about it before. You've talked about it many times when i was in the field. I didn't do many uh megome tests, but i've done a lot of them.

Uh inspecting compressors doing the high pot test and it's something that to learn as a technician to understand, at least how it works. If you ever need to do it, because they highly recommend all compressor manufacturers before you deem a compressor fail, you want to check that the windings you want to do a mega ohm test. You know you want to do all these checks before you say that compressors failed because 30 of the compressors that come back to probably all manufacturers there's nothing wrong with them. Yeah.

If you are going to use a mega, ohm, meter, um or a high pot, you just have to really make sure you know how to use it uh, because it can easily give you a false positive, so it can make you think that a compressor is bad. If it is not bad and often that happens especially on scroll compressors, because they measure a pretty low, uh mega ohm measurement but again look to the manufacturer's guidelines in this case, you know the the ae. 1294 bulletin is a really great bulletin. That kind of addresses this, but really one of the best uses for high pot and mega ohm testing, is to look at winding degradation over time as part of like a maintenance schedule, especially on larger compressors.

Most most cases, you can use your regular meter uh. You know your regular field piece or fluke or whatever you're using multimeter in order to do these measurements on the ohm scale and not require a mega ohm, uh tester, but sometimes it comes in handy and i certainly keep one on the truck for those times. But just don't jump in trying to use one and saying compressors are bad um without fully understanding the uh the tool yeah exactly because there's lots of them that are like 20 mega ohms and the compressor is probably still good. It just says: oh it's red! It's bad so yeah understand the tools, you're working with great point, yeah brian mounting.

They have springs inside them, uh to reduce vibration. These are resilient type mounts and they've been developed. So if you ever hear - and i've heard them before compressor knocking inside one of these spring mounts, so things could happen, um that they break inside too much heat um, they do have a spring on a lot of them. I have some holding force on the top or something to hold them down so that you tip them over they're not going to follow the springs off.

But if someone knocks them over there's a potential pulling plugs. Hermetic compressors are pressurized with seven to 15 psi of dry air before leaving the factory um. It should not be open to the atmosphere longer than five minutes yeah. That's basically that compressor that compressors uh.

Well, it's not the compressor. It's the poe oil, that's gon! Na start, sucking in moisture and if you're, in an area where it's high humidity, probably where you're at lots of high humidity, where you're at is gon na suck as much moisture as possible. There five minutes. So you don't pull the plugs off the compressor and then start piping, everything up and then pulling the dryers and fit everything first and then start brazing that the filter, dryer and that compressor should be the really the last two get the plugs pulled up.

You do not want to. You, do not want to expose that to atmosphere and air if you are going to install them and you're going to do kind of you know fitting dry fitting then get nitrogen flowing sooner. You know get nitrogen flowing to kind of get any air displaced earlier in the process versus leaving it open to atmosphere. Yes, great point: uh pull the larger suction tube, so at the top, there's we'll see down below there's gon na be three plugs.

There's gon na be the suction there's gon na, be a process tube and then you're gon na have the discharge tube. They want you to pull the big suction tube. First, we talked about this before on suction. You always want to pull that discharge because it's higher up first right in case the lower ones you'll get oil splashed on and you've got to wipe it off, and maybe the cell phos doesn't stick.

They go through the brazing procedure. Flow nitrogen, like you just uh, talked about because, if not can lead to blockage from that, you know, oxides, copper, oxides, building up so 100. Do it right. I know i've i've seen in uh, quite a few groups where people are like.

Oh i've raised in systems for 20 years. I've. Never nitrogen purge! Well, okay, maybe you didn't, but that doesn't mean you're doing it right and do it do it right, take take your time, do it right and it gets quicker and faster everyone. I think the big thing is: is that um? Oh, i got to pull up my nitrogen tank.

I got to get my gauge up. I got to set this all up, but after you get your process in place, it doesn't take that much that long yeah. You got to pull your nitrogen out of the truck anyway for pressure testing, so stop acting like it's a big deal. It's just a matter of it's not the way.

You've done it and so just get used to doing it. That way and you'll be more proud of your work anyway. Yeah make sure you uh, you know one side's not evacuated, and the brazing torch then applied make sure both sides high side and low side. You uh, you make sure, there's no refrigerant in there.

If you're removing the charge, so you got to do both sides because you're not going to pull through that plate just on the suction side. And another thing here is talking about unbraising. In some cases you don't have a choice but to unsweat uh. There are some cases where that is the is the case, and you just have to be really careful about making sure all the pressure is out of the system on both sides, but also in general, if you can just cut things out rather than on sweating, it's It's much safer way, safer way, safer, yeah, uh, functional check.

This is a great this 20 service procedures. This is a great section, proper check, proper voltage. You know internal motor protector. Is it open or not? Is it short to ground like we just talked about? Allow time to cool the reset you know: if we go up to number two check, the compressors wire correctly single phase, compressors are so many times not wired correctly.

Uh i've seen it so many times come back and the miss wiring is right there. You know you get that back, so it's on there take your time. Read it check. It double check the wiring before you turn it on, because you can take out that start winding.

Really quick. If you r, wired wrong or the potential relay verify no system, safeties are tripped, you know check condenser fan if the suction falls below normal levels, either it's low on charge or there's a flow blockage. Um check uh compressor current draw compared to copper, mobile or you know they say performance shards, so put it inside kobold get kobo mobile out, scan that compressor and it says, look plus or minus 15 from published values. A faulty compressor may be indicating them.

This is make sure that you check the voltage, but one good thing: they added they added voltage there on the copper mobile now under the new diagnostics section, so you it'll take that into factor as well. Current imbalance exceeding 15 of the average on the three phase. Three phases of a three-phase compressor should be investigated further, so that's for single-phase compressors, where they'll say if it's 15, plus or minus 15 percent of the public faulty compressor may be indicated. So these are little tips and tricks that you need to understand and and this can go um to other compressors as well, because that's 15 would be quite high.

Um deviation, yeah for sure, before replacing or returning a compressor um, you know check minimum recheck the compressor for a high pod or a mega meter winding resistant ability to start before returning, because if you have a humming compressor, it doesn't mean the compressors fail. Oh, i got power to it, i'm checking power got power to, but it's humming. Well it might be that capacitor check the capacitor. It's not giving it that that oomph to start out yeah it could be miswired.

It could be the start. Uh star, capacitor potential relay. Could be the run, capacitors lots of things that can cause that yeah exactly it goes through compressor burn majority contaminant will be removed with that compressor, add 100 uh activated aluma suction filter dryer must be removed after 72 hours clean up procedure, liquid line, filter, dryer recommended Recommended that the suction accumulator be replaced yeah, so i know we've talked about this before replace that suction accumulator on these smaller systems, they're not that expensive, it's expensive to replace a second compressor for sure and then you're and then you're replacing the accumulator too. It's really helpful startup of newer replacement.

No, i put that the blended refrigerant should be charged as a liquid state. So just remember all these new refrigerants pretty much blends and you want to you - want to charge them with liquid and then, if you only can charge, you only get so much in the high side and you have to start charging in the suction there's devices that You can buy from different manufacturers that flashes in there or be really careful, adding that liquid and flash it make sure you're flashing it into the suction. Do not operate uh without enough charge. You need to have at least seven psi in a suction, because, if not, it can lead to early bearing and piston ring failure so make sure that you're not running it with not enough gas and you get a charge.

You get a good vacuum. You get some liquid in in the system and then make sure you're above seven psi, never leave a system with no charge a holding charge or service valve closed without security, locking out the system. I think this is a big one where guys. Oh it's just me.

Working on the system, nobody else is here and all of a sudden, you get busy, you go to another site and somebody else comes and they flick the switch on that. Just oh, it's not running, maybe i'll turn on the switch turn the switch and then boom. You have a smash compressor, make sure you lock that stuff out, because you were the last one on there you're the one that shut all the valves or you left the holding charge in there or whatever. It is just.

Do your due diligence? That's actually a really good point, because we think about lockout tag out in terms of safety, and that is critical for that purpose. But it's also important to lock out tag out equipment so that it's not damaged by somebody who comes along and says. Oh, look! It's just a it's just a disconnect. That's off um it's! Actually! This is a complete diversion, but as we're on the topic of this, i don't know if you saw in social media is going crazy over the recent episode of grey's anatomy, where they had where the nurses went up and tried to fix the air conditioner.

Did you see this okay yeah, it's all over social media right now and everybody's? You know yelling at them, because you see they open up the unit and the disconnect's off and they're, like just flip on the disconnect and i'm thinking to myself. No don't flip on the disconnect. Somebody probably shut it off because they're servicing something and now you're going to flip the thing off on and destroy the system. So it's just just a funny little side down there or hurt the technician.

That's on the roof. Well, no they're actually on the roof it's inside of an rtu, they open it up and yeah they're literally there's a nurse there with a giant oversized wrench. You know about to bang on something you know inside the equipment. But it's you know one of those.

Silly tv moments that we all like to overanalyze love it. I love it, we get into new installation. You know i've skipped this so many times, but i think it's pretty important to understand the manufacturers explaining how to break how they'd like you to braze it. In start with the copper pipe, that's in the fitting, so you heat up so apply heat to area one you see there as it approach.

Brazing temperature apply area to the copper pipe as well as the edge of the fitting, and then then you rotate it around. Make sure you start to heat it up properly and then you move to the fitting itself and very minimal time as close to the compressor always use. If you can some sort of heat heat dissipating, rags or compound whatever you guys use, but you don't want to heat up inside that compressor. So i've seen i've seen compressors come back where they were heated up so much that you could see.

That's where it leaked right there right, because it was heated too much in those joints. This is very interesting because this also follows the process that's taught in the harris guide, but this a lot of a lot of technicians in the field. A lot of senior techs will not teach it this way. They will teach you to apply it to the female side heat that up.

So that way, it pulls the solder into the joint. That's the thinking, but the reason why you do it this way is because by first applying heat to the male end and allowing that heat to conduct it actually conducts more heat into the inside. It's less likely to damage the compressor, but it's also much less likely to damage the copper plating on the uh on the stubs, and that is one of the biggest things that newbie brazers do when they raise in a compressor. Is they apply too much heat to the female stub? They burn the copper plating off and now you've got it.

You know, use a high silver rod with flux like a 56 um. You know flux coated or something like that in order to get the job done, but most people don't know that, and so they just keep trying to go and it's steel and it doesn't work and it blobs up and all that so following this sort of one, Two three start with the heat further away and then work it in. You have to get everything to that dark cherry in order to pull it into the joint. But you want to keep the heat away from the compressor and allow it to conduct in through the tubing, rather than applying it to the outside until the very end exactly - and i never knew this - i didn't know this when i was in the field until i Started working on the the compressor, so um always learning for sure we get down, there's a lot of guides.

You can go through that. We talked about already um, 1182, 1105. 1294, we'll just keep going down nomenclatures, always good to know. You know what i mean to understand when you get better at it, you can understand.

Capacitor start capacitor run always can pull up coba mobile they make. It really emerson makes it really easy to find that stuff out, and i, i think, there's one more section. We probably should talk about there's a lot of part numbers here. You can get that off.

Copper mobile. You don't need this guide, but if we get down to the operating envelopes you can see four four, eight four for nine uh 407a goes from minus 10 to 30.. Don't have any restrictions, oh well. Sorry, 40 uh degree, fahrenheit return, gas temperature, so that's suction line.

Temperature, you can't have 65 in this one like r22, 404 and 507. You get down all the way to -15 fahrenheit, but once again, these these are refrigerants that you're not going to see on new systems anymore. If it's a new system, you're building, if we get down to the electrical section page 18, this is a an important section. I'd like to talk about it's so important to understand what type of compressor you're working on.

If you're working on this figure, 9 capacitor start capacitor run cscr motor, you want to understand all aspects of it so on here you have the start winding the auxiliary line that goes from common. To start, that's inside your compressor to start the compressor, then you have the main winding or the run winding from cdr, which we talked about already. Then you have the potential relay. The potential really is to really stop that start capacitor after you.

It generates enough voltage. So you take that start winding out. Like we talked about earlier we've seen this, you have a failed potential relay, you got ta burn, stern, start whining, i'm sure you've seen it before brian as well yeah, and this is actually one of my favorite pet topics, because a lot of people believe that, if You - and this is true in air conditioning, so i'm kind of going to air conditioning real quick, because this is where some people learn about this stuff. They believe that putting a start, capacitor or a hard start kit, as we call it on a system that wasn't necessarily designed for it, but as a as an add-on that it somehow protects the start winding because it keeps it from getting hot.

But actually it's the exact opposite, because your run capacitor acts as a current limiter. It only allows so much current to move in and out of your your start winding, which is like you, like you called it. The auxiliary winding. That's a really good way of thinking about it, but what the start capacitor and potential relay do is they allow a much larger amount of current to travel through that start winding, but for a very short period of time i mean you're really only getting that compressor Up to about 80 percent of its running rpm before the back emf or the back voltage is great enough.

The motor generates its own voltage is great enough to uh, create a potential between points two and points five, so between common and start to open up that relay so that relay starts closed once it gets up to that running, speed 75. 80 percent. Then it opens that potential relay and takes that star capacitor out of the circuit. But if you wire it wrong or if that that uh potential relay fails and that start capacitor stays in the circuit, then that start winding sees high current all the time and that results in start winding failure or it potentially start capacitor, uh or potential relay failure, Meaning more catastrophic failure.

So when you see that you know situation where the start capacitor is kind of blown up on you, that's the time to stop and think about. I don't want to necessarily just replace this replace the start. Capacitor, let's go ahead and replace the entire gear, the potential relay and the start capacitor, because it's very possible that that constant duty of staying in the circuit is what caused that star capacitor to fail. Because that's you know: they're not designed to stay in the circuit.

All the time, that's why they look different they're, a different size than run capacitors for the same sort of capacitance rating. So understanding that about them, i think, is - is very helpful and, and often we can prevent problems by you know making sure that hey they're wired, properly b you're not cutting the resistors off of them, like we've, already talked about uh and then not over applying them. If it's necessary for the application, then use them uh, if it's not, then don't use them unless it's necessary yeah and that's a good point like if you have a start cap fail just replace all the electrics yeah you know just it could be something else that Just like you said so, that's a good point, and so we've talked about it, but the whole purpose of the start capacitor is to boost that starting torque, and you want to the whole point, is to create a magnetic field. So what it does is it? It shifts or puts out a phase that auxiliary or let's start winding, compared to the main winding.

That's the whole point of the start cap and then what the run cap is. It pulls it back into phase so that compressor can continue to run. So just so.