How Air Conditioning Works And What Can Go Wrong

What's going on, everybody? It's Richard Kohberger here, the blue collar nerd. And in this video, I'm going to be going over how an air conditioner works, the basic components that make up an air conditioning system, as well as some common things that can go wrong. So first of all, how does an air conditioner work? Well, if you've ever used one of these compressed air duster can things, then you've experienced firsthand the basic phenomenon that is harmful harnessed and used for air conditioning. Now, despite the common name of compressed air, these things aren't actually just like air compressed into a can. If you shake it, you can tell there's clearly a liquid in here. You hear that? Do a little ASMR real quick. And the liquid that's inside here is a refrigerant. It's a different refrigerant than what's used in air conditioners, but a refrigerant nonetheless. And it works the same basic way. So inside of this can, it's a high pressure environment, and that lets the refrigerant stay in its liquid state state. But when I pull this trigger, then a valve is opened up into the environment that I'm in, which is a lower pressure environment. Kind of going back to 8th grade science class here. Molecules want to establish equilibrium. They want to go from high pressure environments to lower pressure environments until they reach a state where the pressure is even. So when I pull the trigger, the refrigerant moves out of this higher pressure environment, and in doing so, it rapidly evaporates, changing phases. It changes from its liquid phase to its gaseous phase. And if you've ever used one of these, then you probably know that the longer you hold that trigger down, the colder this can get. You can go and it just keeps getting colder and colder. You can feel it in your hand. It can even start, like frosting over until eventually it'll get so cold that you might have to stop. You might have to just like drop it. Like it's hot, but it's cold. And that is because the process of evaporation absorbs heat. Now, heat is a different thing from cold heat. Heat is a measurable unit of energy, but cold is a sensation that we feel depending on the amount of heat. So you can't create cold. There's only varying amounts of heat. So when this can gets cold, it's because the heat from the can is being absorbed and it's actually being absorbed into the refrigerant. So it's coming back out into that Gaseous refrigerant. So air conditioning works exactly like that, except instead of just letting their gaseous refrigerant out into the surrounding environment, we. We keep it contained in a cycle, and then we condense it back down into its liquid form so that it can be once again evaporated, condensed back down into liquid, evaporated again, over and over. So the most common type of air conditioning system is what's called a split system. This is what you'll find in most residential situations. A house, a townhouse, an apartment, things like that. And with a split system, the air conditioning system is broken up into two parts. It's split. So there's one part that is inside and there is one part that is outside. And these two different parts are connected with copper refrigerant lines. So the indoor portion of the air conditioner is where the evaporation happens. The piece of the system that does the evaporating is called the evaporator coil. This is what most evaporator coils look like. It's kind of this a frame situation. So refrigerant is evaporated in the evaporator coil. And just like the outside of our can got cold, the evaporator coil gets cold. It absorbs heat from the metal of the coil itself, as well as the surrounding air. And so we blow air rapidly through that coil, which absorbs the heat out of the air. And then that air is pushed through the ductwork and eventually out of the supply vent, where you feel the cold air coming out. So the refrigerant, which is now a gas, is pumped to the outdoor unit. The outdoor unit is sometimes called the condensing unit or the condenser, because that is where the refrigerant is condensed back down into a liquid. Now, in order to get that vaporized refrigerant back down into a liquid form, we need to create a high pressure environment for it, just like we have inside of our can. So there is a component in the condenser called a compressor. And as the name implies, it takes that gas and it compresses it into a much higher pressure gas. And it also serves as the pump that keeps refrigerant cycling throughout the system. So we've got refrigerant that is now a gas being pumped into the compressor. The compressor then takes that gaseous refrigerant and compresses it down into a much higher pressure gas, which releases the heat that that refrigerant had absorbed. So now we've got the refrigerant molecules in a High pressure environment, which gives the refrigerant the potential to be in its liquid phase. But it's not yet, because the gas has been compressed, it's released some of that heat, and we need to expel some of that heat and blow it away. In order to actually make the refrigerant liquid again, we need to cool it off a little bit. And during this process is when that refrigerant becomes fully a liquid again. So the copper refrigerant line is wrapped around that outdoor unit over and over. That copper line is then surrounded by these metal fins that serve as heat sinks for the heat to kind of sink into and pull it away from the refrigerant and get it distributed. And then we've got a big fan that's pointed up, so it's pulling air in through those fins, taking heat away from the refrigerant, away from the coils, and then the heat is going up and out, being dumped into the outdoor environment. So if you go outside on a hot day when your air conditioner is working and you put your hand over that fan to feel the air coming out of it, you might notice that air is pretty warm. That is the heat energy that used to be inside your house. We are literally absorbing the heat from inside the house and dumping it outside. So as we're cooling this high pressure refrigerant down, it is condensing back into a liquid. Then finally, that liquid refrigerant is sent back into the evaporator coil and the cycle repeats. And that's basically how it works. Now, you might have also heard of a heat pump. So what is that? Well, a heat pump is an air conditioner. It works the exact same way that I just described, except in addition to operating the way I just described, where it takes heat, absorbs it from inside and dumps it outside, it can also run the cycle in reverse, meaning it can use its condenser coil as an evaporator and its evaporator as a condenser. It can absorb heat from outside and dump it in inside. So remember that heat is a measurable unit of energy, and cold is a sensation that we feel when there's less heat. So on a cold winter day, we feel cold because, yes, there is less heat energy in the surrounding air, but there is still heat energy, plenty of it. And with a heat pump, we can steal from Mother Nature. We can take all our heat and use it for our own perverted purposes inside. Anyways, let me take you outside. We're going to look at my Air conditioner. And we're going to get a little bit more in depth on some of these components. Okay, so this is the main condensing unit for my house. Now, it is running right now, and I would like it to not be. So the first thing I'm going to do is I'm going to come over here to this box, I'm going to open it up and I'm going to just grab this thing and pull it out. So that's called the disconnect box. Basically, you can pull this thing out and that breaks the circuit and stops sending power down that line and into the unit. So if we look down here through this grate, you can see it's mostly empty inside of here, except for this big black cylinder thing in the middle. That would be the compressor. And you can see the copper lines going into it. The compressor is usually just a big black metal cylinder. Mine has this little blanket thing on top of it that's just to make it a little quieter. It kind of dampens the sound. But I'll throw a picture up of what a naked one looks like. Nsfw. Okay, so anyway, obviously this is, is the fan. Those are the fan blades. And then it's attached to the fan motor that actually spins the fan. And then this piece is just a metal cage that protects the actual coil. But if you kind of look up in there, you can see all of these tiny little squiggly fins. So the actual copper line that carries the refrigerant is running through here, and it's surrounded by all those squiggly fins, which again is a heat sink to help carry the heat away. And when that fan runs, it draws heat through. Screw those fins up and out, carries the heat away. Now, right down here in the bottom corner of the unit, those are the copper refrigerant lines. So we've got two lines here. We've got this thicker one that's insulated. At least it should be insulated. And we've got this skinnier one. The thicker line is called the suction line. It has the vaporized gaseous refrigerant inside of it, and it's called the suction line because the gaseous refrigerant is being sucked. Sucked this way into the compressor. The compressor then compresses it down to a high pressure gas which is very hot. So it goes around and around and around while the air kind of rushes past it and carries the heat away. And then it comes back out this line, this is called the liquid line because it is carrying the liquid refrigerant. So on this line, the refrigerant's running this way into the condenser, and on this line, it's running the opposite direction back to the evaporator. Now, back over here, you might notice that nasty little fella. That's a PVC pipe dripping water. That is the drain line. So air conditioners not only take heat from inside the house and move it outside, but it also takes moisture, humidity from inside the house and moves that outside as well. That's because when humid, air comes in contact with a cold surface, it creates condensation. So the moisture contained in that air condenses on the surface of the cold thing. And if you've ever had a cup of cold liquid in a humid environment, Then you've seen this happen. It's the sweat that forms on the outside of the cup. It's why we use coasters. Right? We're using coasters, Right. Anyways, all that water has to be dealt with somehow, which is why we have this PVC drain line. So the water just drips down that evaporator coil and runs through that line and moves outside. Okay, last thing I want to show you out here, I'm going to take this panel off and show you some of the components that are behind it. How dare they deliver mail while I'm shooting a video. What is so rude? So, as you can see, there's really not that much in here. We've basically got two main electrical components inside this compartment. We've got the capacitor, which is this silver cylinder right here. And we've got the contactor, which is this black switch. So the capacitor, it's. It's often compared with a battery. It's not a battery, but it works in a similar kind of way in that it does store energy. And it has two main purposes. To help start the unit and to control the voltage, Keep a nice steady level of power going into the unit while it's running. So to start a compressor from a dead stop, it takes a lot of energy. So the capacitor is able to give it a nice big jolt of energy right when it's starting up so that it can get going. Okay. And then we have the contactor. The contactor is just a switch. It's. It makes the unit turn on and off. So basically, it's engaged right now. So let me just pull off this little guy. Okay, so basically, this middle piece here is a little plunger that goes in and out. So if we look kind of Closer here you can see there's a metal disc on one side of the contactor and a metal disc on this little plunger piece. And then running into the contactor are wires coming from this brown wire. This is the thermostat wire. So when the thermostat says, hey, it's getting kind of hot in here, we need some air conditioning, it sends the signal through that wire that I just pulled off, which engages this plunger, closes the circuit, turns on the air conditioner, and we'll just put that back where we found it. Now, you might also be wondering what this little black box is. That's a little diagnostic box. You'll find that on some newer systems that is not an essential component of the air conditioner. That is just there to help a technician diagnose the system faster if there's something going wrong. And again, that's something that some newer systems have, but not every system has something like that. So that's basically it for out here. I'm going to put that panel back on, I'm going to put my disconnect back in. Very important. Sometimes technicians will forget to put the disconnect back after they've been working on the unit. Then they have to drive all the way back out just to plug the thing back in. It's very embarrassing. And everybody calls them mean names. Ask me how I know. Okay, now let me show you the other half of the system, which is up in the attic. There's not quite as much to show you up here, which is very good news because it's all kinds of hot. Okay, so here you can see our copper refrigerant lines. These are the same lines that we saw outside. So we've got our thicker line, our suction line that's carrying the vapor refrigerant, and we've got our smaller liquid line that's carrying the liquid refrigerant. And then inside of this box, that is where our evaporator coil sits. So in my case, the evaporator coil sits on top of the of my furnace. If you have a heat pump, meaning you have an all electric system, you will still have a box here. But in that case, it's referred to as an air handler because there's no gas, there's no fire, it's not a furnace. So we've got refrigerant flowing into the evaporator coil through this line. The refrigerant gets evaporated. That makes the coil in this box very, very cold. So what we're doing is we're sucking in air from the house through these ducts here. So the air goes in, it goes through through the filter, which is right behind this door. Right behind here is our blower motor. That's the fan that pulls air through the system. So the air gets sucked in from the house, blown up through this evaporator coil, which is going to absorb the heat from that air. Then the now colder air goes up in here, and it blows out through these ducts. These are the supply ducts where it blows the colder air back into the house. And then, of course, the now vaporized refrigerant goes out through this line back outside to the condenser coil so that the cycle can repeat. And then down here at the bottom of the box that houses the evaporator coil is our drain line. So that's what's going to carry away all of the condensation that is created by the evaporation process. All right, so now that we have a basic understanding of how an air conditioner works and the components that make it up, let's talk about some things that can go wrong. Well, one issue you can have is a dirty air filter. Most people know that the air filter, they're supposed to replace it on occasion, but you know how it goes. Life happens. People forget. Plus, not everybody really understands that a dirty air filter can actually cause the system to not work anymore. But it can, because when an air filter gets so clogged up with dirt that air can no longer easily pass through it, that's going to restrict airflow to the point that we're not able to get enough air past that cold evaporator coil. And we need to be moving fresh air through that evaporator coil so that it can absorb the heat from that air. Otherwise, it's just going to keep absorbing heat and absorbing heat and absorbing heat from whatever environment it's in, which will eventually cause it to freeze and become a big block of ice. And while we can blow air through an evaporator coil, we cannot blow air through a block of ice. So once that coil freezes, your already restricted airflow from that dirty filter is now completely restricted. We can't get any air pass through anymore, and you're not going to feel anything coming out of the vents. Now, a dirty filter is not the only thing that can cause an evaporator coil to freeze. For example, an improper refrigerant level can also cause the evaporator coil to freeze. Typically, the problem is going to be that there's not enough refrigerant because it is leaking. Although too much refrigerant can also be a problem. But remember that this system that we have is a closed system. The refrigerant is supposed to stay inside of those copper lines and just get evaporated. Condensed. Evaporated, condensed. It's never supposed to leave. It's not supposed to go anywhere. So if refrigerant levels are low, one of two things happened. Either it never had the right refrigerant levels in the first place, it wasn't done correctly when the unit was installed, or the levels were correct at one point and you have a leak somewhere. Now, a leak can happen anywhere throughout the system, but most often we find them in the evaporator coil. Evaporator coils are vulnerable to springing some leaks over time, mainly because they're always wet. We talked about how the humidity in the air is always condensing onto those coils and then dripping down and going out the drain line. So that coil is wet pretty much the entire time that the unit is operating. The evaporator coil is also exposed to anything that we're putting in our air inside the house. Cleaning chemicals, fragrances, et cetera. And these combined factors can cause the metal that the evaporator coil is made of to corrode. That problem is exacerbated when winter rolls around, because now we're gonna be blowing hot air through that evaporator coil, which will cause the already corroded metal to expand. And that can be when the leak happens. Now, some coils are made of aluminum versus copper and steel. Aluminum coils are becoming more and more common. And in my experience, anyways, aluminum coils don't spring as many leaks. Leaks. Another thing that can go wrong is that PVC drain line that carries the water away from the evaporator coil and puts it outside. That line can become clogged, either with a piece of debris or just because it also is wet all the time. Algae and stuff grows in there and eventually can cause a clog. When it gets clogged, that means water can't move through it and get outside. And so it backs up and starts dripping down into the drain pan, which is that metal pan that the indoor unit sits inside of. Drain pans are equipped with safety switches, or at least they're supposed to be. It's something called a float switch. So when that pan fills up with water, there's a little bobber inside of the switch that floats. And when it gets up to a certain level, it cuts the system off something else that can cause a problem is a dirty condenser coil. So remember, we've got two coils in this system. We've got the condenser coil and the evaporator coil. And both of them have these very close together little fins that serve as heat sinks. And because there are so many of those fins so close together, they can collect dirt. Now, the indoor coil is protected by your air filter, so typically that one doesn't get very dirty. The outdoor coil, on the other hand, is not protected by any sort of filter. And even worse, it's pulling in outside air. So things like grass clippings and dust from landscaping all get sucked up in there. And over time, once it gets dirty enough, it can prevent the coil from doing its job, which is to expel the heat. So most H Vac companies offer maintenance plans. And staple things that are done during the maintenance plan include changing the air filter, cleaning the outdoor coil, and blowing out the drain line. Those are done to prevent those three issues. Some other common things that go wrong. Remember those electrical components that we talked about outside the capacitor and the contactor? Either one of those components can also go bad. In fact, they're nearly guaranteed to go bad at some point during the system's lifespan. Those, I would say, are some of the most common problems. Now, obviously, there's a bunch more things that can go wrong. Any of the components that we talked about in this video can have a problem and go bad. The thermostat wire that runs into the unit, that little brown wire that I showed you, sometimes that will get chewed up by a weed eater or something, you can have a problem with the thermostat itself. You can have complicated electrical issues. All sorts of things can go wrong. This video is not to give you technician level knowledge. It's just to give you some basic understanding. I'll close you out with a weird one. Dog pee. Dog pee can ruin a unit. So some dogs that spend a lot of time outside, they'll see that condenser unit and they'll think dibs. And eventually it can actually eat away at the fins and make the unit look like this. Anyways, on that note, that's all I got for today. Be sure to hit, like, if you liked this video and found it valuable, be sure to subscribe to my YouTube channel. If you haven't done that already, hit that bell icon so that YouTube notifies you. Anytime I upload a new video. I am considering making more videos like this that focus on furnaces or duct work. So if that sounds interesting to you, please let me know. Appreciate it. Peace.