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Hi, my name is Rajvir. I’m from HVAC Technical Academy and today we’re going to be discussing duct board and how it works, where it’s in the system, and what it’s used for. So, right here we have our duct board laid out. I’ve done my first two cuts. It’s going to be 10 by 10 each cut. So, let’s do the last two cuts. So, we’re going to use our square and use our cutter. Make sure the sled’s facing forward. Apply even pressure. And then for our last cut, we have three

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blades. We’re going to cut the excess off. And be careful not to get it on your skin. It’s very itchy. So after we made our cuts, then you’re able to assemble it into a plenum. So, you’d use staples and then you’d use tape and then your box would be sealed and it would look something like this, which then goes on top of the air handler with fab and mastic to make sure it’s sealed and has proper air flow and insulation. So basically what the duct board or plenum does is it supplies

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insulated air throughout the ducts which are in your attic, come out the registers, and help air condition your house. A couple things—if you check for if it’s going bad, it could discolor and leak air and then ultimately cause you to have high energy bills because it’s not working efficiently. The ducts go on with a collar and then you’re able to mastic these on as well and then they’re just hung up and then back to the register.

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Yeah, that’s pretty much all I have to say today. And my name is Rajvir from HVAC Technical Academy and have a nice day.

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Hi, my name is Nick with HVAC Technical Academy and today I will be talking about low voltage wiring, also known as thermostat wiring in HVAC. Think of low voltage wiring as the nervous system of our HVAC unit. It sends signals to different parts to power up the unit. So, we typically get our power from our transformer, which brings in 240 volts and steps it down to 24 volts. That’s what our thermostat wire runs on. Now, we have several different colors on our thermostat wire. It’s important to

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not go by the color necessarily, but the terminal of the corresponding letter in our thermostat. So, it plugs into here. And a typical wire setup of what we see on a heat pump, we have R, our red wire is our 24 volts that powers the system. We have blue and black are common. Orange powers our reversing valve in a heat pump system. Green powers the indoor blower motor and the air handler. Yellow energizes the Y terminal in the outdoor unit and white is our call for our heat strip.

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Now we can have wires going into the thermostat. This is essentially if this wire is our nervous system, our thermostat is the brain of the system. It plugs in from the wall into each of these terminals and you can adjust the thermostat in order to call for certain things. So, for example, if you wanted to call for cool, our R wire, our 24 volts would energize our G wire to power the fan blower motor and our Y wire to power the outdoor contactor. We don’t have many problems associated with low voltage, but there are a few.

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There could be misplaced wires. So, if we have a Y wire and a call for heat mixed up, we could be calling for cool on the thermostat and be getting heat. Things you want to check for are breaks in the wire, misaligned wires, and we also have several safety switches in the system. We have a low pressure and high pressure safety switch that, if we’re not getting enough refrigerant or we have too much pressure in a system, it could disrupt the 24 volt circuit and

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turn our system off. We also have some fuses that could be blown that interrupt the circuit and turn the system off. And that is our class on low voltage wiring.

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Hi, my name is Nasheem from HVAC Technical Academy. Today I’ll be talking to you about the defrost board. The defrost board helps regulate and maintain the defrost cycle which can prevent ice buildup on the outdoor coil. So the defrost board is usually located on the outdoor condenser unit near the contactor in the access panel. What the defrost board does is it sends the unit into defrost cycle by reversing the flow of refrigerant, turning off the outdoor fan motor, and signaling to the indoor electric heat to

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come on. It will put that heat on a timer and when that timer is shut off, the outdoor coil should be defrosted. Now, there’s a couple things that can cause a defrost board to go bad. It can be something as small as a surge in power, debris from being outside, moisture in the air, even insects and things of that nature. You can troubleshoot the defrost board by taking your screwdriver and going to the test pins to force the defrost cycle. When you do that, the defrost cycle should

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start and you should hear it turn on. If that does not happen, then you have a faulty defrost board. Switching out a defrost board usually entails removing the entire board and also the sensor alongside with it. My name is Nasheem. Thank you for looking at my video about defrost boards.

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My name is Mike Moynihan from HVAC Technical Academy. I’m going to show you, Mrs. Smith, what we refer to in the industry as a pump down. Basically, a pump down is taking all the refrigerant from your inside unit anywhere in the lines. We’re going to suck it all the way back to your outdoor unit. We’re going to trap that refrigerant inside here. That’s going to allow us to make any repairs on your copper lines, on your filter dryer, your evaporator coil, your thermal expansion valve.

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Anywhere that holds refrigerant will now not have refrigerant. It’ll be trapped inside here. So, the red hose is my liquid line. The blue hose is basically my suction line. So, what I’m going to do to your unit, Mrs. Smith, I’m going to close my high side. And then I’m going to very quickly close my suction line, the blue hose. I’m going to close that, which is going to suck all that refrigerant back to this unit very quickly. That process is cheaper than doing a recovery, which would cost you a lot of

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money. And this is much quicker. Thank you, Mrs. Smith.

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Hi, my name is Melody. I’m with HVAC Technical Academy and I’m going to be talking to you about heat strips today. So, your heat strip is located on the top of your air handler. You see it right in here. We’re going to go ahead and take this out. I’ve already removed two of the three screws that keeps it in place. Okay. Move that up to the side. And we’ll go right here and disconnect our wires. Just like that. Okay, we’ll put this off to the side because it’s a bad heat strip.

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Perfect. So, now you got this little space right here. This is exactly where it sits. Installing a heat strip is fairly easy. We’ll take this one, put it right back inside. Just like this. Perfect. And then we are going to reconnect. Right. Just like that. And now when you switch out your heat strip, you want to check for continuity. That’s how you’re going to know if your heat strip is good or not. We’ll switch our multimeter over to ohms. We’ll set right here. We’re going to put

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both of our needles on each side. That beeping right there indicates that it’s good. You have continuity. Now, if it was just silent, that would mean you have a broken path or an open line and something could be wrong like your coils could be broken or bent. Heat strips generally are going to be inside your air handler for emergency heat. If you have a heat pump condenser, the only reason it would turn on is if you’re in defrost mode or something’s wrong with your condenser. Now, if you

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have just a straight cool, this is going to be your primary source of heat. Usually your heat strips are going to be about three and a half to 5 kilowatts and that’s going to be on a 30 amp breaker. How you could tell your heat strip is bad—you might smell excessive burning or it could be stuck on and your heat bill will go sky high. Yeah. I think that’s all I’ve got for you today on heat strips. Thank you for taking the time to listen and watch the video.

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Hi, Miss Smith. My name is Leo from HVAC Technical Academy. Today, I’m going to talk to you about a key component in your AC unit, the contactor. Essentially, it’s a component found in your outdoor unit. It acts as a heavy duty power switch. It controls high voltage power that goes to your compressor and fan motor. And let me show you where the contactor is and how that works. It’s inside the electrical panel of your condensing unit. When it goes bad, your unit might not start at

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all or even worse, your unit can stay running even though you turn your thermostat off, which can seriously cause damage to your compressor. It works as the 24 volt signal comes from the thermostat to the contactor. The contactor coil creates a magnetic field to pull the metal contact down, finishing the circuit and sending power to start the cooling process. To inspect it, we use a multimeter to check continuity across the contactor and also verify the 24 volt at the coil.

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There’s a few common reasons that cause a contactor to fail, including carbon buildup because of electric arcing and bugs like ants or lizards getting stuck between the contactor. Also, due to age, the coil could be burned out and it can also be caused by an electric surge. Thank you for checking out my video. You have a nice day.

Hey guys, how you doing? I’m Kevin Thompson here at HVAC Technical Academy and I’m here with Mrs. Smith. Mrs. Smith has some questions for me about her filter dryer and she wanted to know exactly like what is a filter dryer? So, a filter dryer is a tool I would say that goes on your high side line that enables the flow of refrigerant to flow through the system. You have two types of filter dryers. Biflow, which this one is biflow. The flow goes both ways, or single flow as Miss Smith has.

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Why do I have single flow and not a B flow? >> So, you have single flow because on this condenser, this condenser is a straight cool. A straight cool meaning it only has one flow and it doesn’t have a reversing valve. A heat pump is a system that normally uses a reversing valve and that one we would use a B flow on. Oh, because it goes both ways. >> It goes both ways. So when it turns to heat or when you turn the heat on, it reverses the process and goes back the other way.

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Oh, >> yes, ma’am. So, >> so how would I know it’s bad? >> So, for testing to see if it’s bad, you would clamp your meters on both sides of this. And if the temperature split between if it’s not a split between three degrees, then it would be bad. If it flows and it’s regular temperature, it wouldn’t be bad. And normally, you can feel like through the line, you’ll be able to feel the difference in temperature.

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Oh, >> yes. That’s a way you can test without a tool. >> That’s interesting. >> Yes, ma’am. Well, would that be all the questions you have, Mr. Smith? >> Yeah. I think that’s about it. Okay, well you heard from Miss Smith. Hopefully I taught you guys something and I see you guys in the next video.

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Hey guys, this is Isaiah Marshian with HVAC Technical Academy. Today we’re going to be talking about the vacuum process. What it is and what happens if we don’t do it. When making a major repair or when installing a new system, it is a crucial step to pull a vacuum on the system. Well, what is the vacuum process? Here we have the vacuum pump. The vacuum pump pulls the vacuum on the system which removes all non-condensible such as air and moisture from the system. We hook our manifold

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gauge up to the high and the low side and then we hook our vacuum pump to our manifold gauge. That is what causes the suction. EPA requires us to pull a vacuum of 500 microns. We can read our microns through this manifold gauge. We can also use a micron gauge to read the microns that we are pulling. Microns are simply the measure of atmospheric pressure in a system. So once we pull it down to 500 microns, we usually wait about 5 to 10 minutes, allowing the system to level out

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and make sure that we have no non-condensibles in the system. Pulling a vacuum on the system is not just the best practice but it is also EPA required and we can ensure efficiency and longevity of the system. Non-condensables in the system can cause damage to the compressor and the evaporator coils. It can also cause freeze up in the evaporator coils because moisture can freeze up in the system if we don’t pull it out with a vacuum pump. When the moisture freezes up in the system, it can also reduce heat

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transfer which is an effect on our efficiency of the system. When we have non-condensables in the system, it can cause damage to the compressor and the evaporator coils, which is a major repair and can get very expensive. So once again, this is the vacuum pump hooked up to the manifold gauge. This is our vacuum line that we hook up to the manifold gauge. And our gauges are hooked up to the high and the low side. This is Isaiah Marian with HVAC Technical Academy.