So we're being called on a walk-in freezer, you can hear that sound. It's not frozen up sounds like it's running, but the evaporator fan motors aren't coming on definitely sounds like we're starving. It's like it was iced up at one point: there's nothing back there. I walk up on the roof.

This is my condensing unit and it's running trying to little Hardaway, so we're gon na take all the panels off put some gauges on this guy. Okay discharge lines: hot suction line is like cool, not cold site glass is empty. So, what's happening without even put my gauges on it, I can already tell you that more than likely we are feeding vapor to that evaporator downstairs. That was the hissing sound okay.

So this is kind of what I thought it was so you've got a head master system here. I've got some probes on there, refresher discharge line coming into the head, master, stops and waits for the head master bypass. This is the liquid drain coming out. The bottom of the condenser refrigerant goes through the head through the condenser, when the headmaster is not bypassing, it stops goes back up, runs through the condenser back and forth.

Back and forth turns into a liquid comes out liquid drain through the bottom side of the headmaster. Down into the receiver, that's if it's not my passing now, if it's bypassing discharged gas runs through the condenser, but also goes right here passes through the headmaster, this valve shuts off and doesn't let refrigerant it slowly metres it out of this point right here, but it Lets the discharged gas bypass straight through into the receiver, and that's exactly what's happening right now. I'll come down here we can see so our discharge line temperature is 144 degrees. Our liquid drain is 88 degrees and our liquid line temperature is 130, so notice.

The liquid drain is lower than the liquid line, so that means that my Headmaster's bypassing, but the problem is get the cyclist sigh class is empty, so what's happening without the winter charge. In that receiver remember, this receiver needs to have a liquid seal in it of winter charge. The extra refrigerant we add to the system. So that way we can properly flood the condenser, but right now we don't have that refrigerant, so we're dumping hot vapor right into the receiver and it's running down the other side of the coming out of the receiver, going directly downstairs to the t, -- xv and That's why we heard that sound inside the evaporator.

The hissing sound is because we're starving that evaporator we're feeding just pure vapor to that T X B and that T X B doesn't work with vapor has to have a hundred percent liquid. So we need to do. Is add refrigerant to this system we obviously have a leak, but we're gon na add refrigerant and get it operational. I definitely see why doesn't pick up as good on the camera, but there's oil all over this right here.

This discharge line, but we'll address that later we're gon na get gas in it first and get it off. So you hear that sound that you've, a British starving, it's not dropping the temperature of the evaporator below 20 degrees. Therefore, the evaporator families aren't turning on so we're going to start, adding in now notice my head pressure coming up above 180 as it does. I have start seeing some action in the headmaster, slowly, metering, the refrigerant in there just a ball valve - noticed something it didn't take much.

I just needed the winter charge, really extra refrigerant that needed to be in the system. We got a liquid line. Temperature 84 in liquid, our liquid drain 83 190, head pressure, see I just added the refrigerant until it cleared the sight glass now keep in mind, I'm still gon na have to add a little refrigerant. Let's go over this real quick over here.

So me as a technician I have no way of knowing how much refrigerant is in that receiver. The only way I could do this is, if I brought my recovery machine up here, recovered all the gas out of it and then calculated the charge, which is all possible, but it's not practical. So as a technician walking up on a system, that's low in refrigerant. How do I know how much it's missing and how do I know how much more I need to add? Okay, there is a calculation if you follow the heat crafts head master manual or, I should say spoilin for the l AC valves.

They have a manual that tells you how to calculate it. When you're running into this situation, where you would essentially add the refrigerant until the sight glass clears, then you're gon na calculate the volume not the condenser can hold. But again, that's not a real practical thing for me to do right now, because I'm out here servicing this unit, what I'm gon na do is I'm gon na fill this system up with the maximum amount of refrigerant I could possibly put in it. Okay.

That, essentially, is when that receiver is pumped down, meaning I shut the liquid line coming out of it off, and I let the compressor pump all the refrigerant into the condenser and the receiver. I cannot let that receiver fill up more than 80 % of the way. So my liquid level should be approximately right here on that receiver. So what you got to do is take a heat source and this can be very dangerous.

If you don't do this right, you need to take a heat source notice. I said each source. Okay, you need to make that decision. You need to take a heat source that can heat up that receiver, but that won't exceed the maximum temperature of that receiver, which that receiver will have a soft plug on it.

If you look at the data, play, it'll probably tell you, but I can tell you right now that most receivers, the the melting point of the soft plug is about 430 degrees 400 somewhere in there. So my heat source that I'm going to use cannot exceed that temperature and all that you're going to do is pump down the system and I'll show you once I get ready we're going to pump down the system, we're gon na heat it up and they're gon Na take our finger and run it and all of a sudden boom it'll get red-hot right there. That is our liquid level once I've done, I haven't done it yet, but once we add refrigerant, until we put the maximum amount in there, which is gon na be 80 % pumps down, then we fill it up. That's the easiest way and most practical way that I find in the field to do this when we're on the fly.

Now, if I have the time sure we cover all the refrigerant calculate the charge, weigh it in that's, that's the best way, but not always practical. Like our system, 21 back 22 back we're cyclist. Now it's important to know what my ambient temperature is right. Now my ambient temperature is 67 degrees, I'm in Southern California the coldest that we're going to get in this particular city, La Habra.

California, we got to go to the extreme the absolute coldest day. So typically, I say all over Southern California. Unless you get into the high desert of the mountain regions, the coldest you're ever gon na get is gon na be 30 degrees. Okay, so I cleared this site glass at 67 degrees.

This. What I'm gon na tell you right now only applies because I have a headmaster on there. Okay, so essentially I have enough refrigerant for that headmaster to bypass at 60 degrees. I still need to add extra refrigerant, okay, I'll point out in the manual I'll go to it at the end of this video and show you where, when we actually calculate the flooded charge for this, if we did the the unpractical way, which I told you it Actually looks for the lowest temperature that you could possibly get, and you calculate the flooded cap at or the flooded charge at that temperature, and it tells you how much refrigerant you need to add.

But again going back to what I said. The practical way is just to put the maximum amount of refrigerant in there, but you have to be careful because I'm dealing with a small system. This is like a two three horsepower condensing unit. If I was dealing with a big supermarket system yeah, we might be dealing with hundreds and hundreds of pounds of refrigerant I'm dealing with no more than you know.

I'm guessing 18 pound refrigerant total charge, and it's not going to take that much right now. So I'm gon na go ahead and keep charging this guy up. I'm gon na put a little more refrigerant and then we're gon na pump. It down bring us back here notice.

You don't hear that hissing sound of the evaporator starving anymore, because we're now feeding liquid to RTX meeting you notice, the fans turned on too, because the evaporator temperature dropped below 20 degrees so to pump this system down. I closed the liquid line service valve all right front. Seated it all the way pressors, not shutting off it's a story of the day. It looks like we got a low-pressure control.

That's needs to be adjusted also there we go shut off about negative four okay, so I pumped this down and I'm running my finger up, but right now I've already ran my heat source across it and it gets hot right there at the 3/4 mark. You actually see it with a thermometer to infrared, so let's go down here, watch it and then watch what the temperature jump is. As I go up 95-96 and let's draw back down, drops down to about 80 degrees, 79 degrees. So our liquid line right in there and you can actually fill it with your hands to boom.

It just gets hot right there. It's kind of hard to tell that's my soft plug right there, so your heat source, whatever you use, make sure it doesn't exceed that soft plug again start at the bottom of the receiver. 7075 degrees slowly climb. But right there is where we really start to draw up temperature.

It's the road in that range: let's do it again: 78, eighty and those gets hotter and hotter and hotter it's losing temperature too, but yeah right there. So that's my liquid line. I usually like to mark it too I'll use like a paint marker for now. I just got a sharpie and I'll put a date on it.

So that way, the next guy knows that I filled it up on this day, I'm obviously going to try to find the leak right now to whether or not I fix it tonight. I don't know, but we'll at least make sure we got enough refrigerant in there. Here we are running it's all charged up, we're right about the point where it should start by passing, provided about 180 head pressure, but it needs to drop below 118. That's when it starts to bypass.

It's also important to know that it's not a full bypass or not bypass it, it modulates back and forth. So as the pressures drop, it opens a little more as it raises it will close a little more and it's just kind of floating. So liquid line temp 82 degrees discharge line, temp 122 and liquid drain is on t2, that's 82 degrees, so liquid line temp and liquid drain, let's go right here, liquid line going into the receiver liquid drain coming out of the condenser discharge line. It stops because it's not bypassing, and it runs through the condenser like normal and makes liquid refrigerant coming out the liquid drain dumping in to the receiver.

There's our liquid level right there maximum amount of refrigerant we can put in that system now to find the leak. Now it's kind of late today, so I don't know if I'm gon na actually find the leak I'll do I'll. Look at that oil spot real quick, but I'm not gon na go climbing in the Attic tonight. It's almost four o'clock, so I cleaned it up.

A leak check before I took the cap off couldn't find anything use. My electronic couldn't find anything. It's amazing what bubbles can pick up, though, so it isn't that Schrader once if I can get this camera to focus here. It's not gon na focus on me, but it's coming out of the Schrader focus the Schrader's leaking by so for now very common on these systems.

If you guys haven't worked on these and whenever the discharge line is like basically on the compressor, especially on these POC compressors, these CF twelve, this is a smaller Copeland, the rubber o-rings in that Schrader core our guarantee or melted inside that thing. Most of the time, you can't even get the Schrader core out on these ones right here that it's like right on the compressor. This is a cold zone, condensing unit, it's a really common place for them to put a high side port and we always have those traitors being melted. Most of the time you just got a permanently seal them off.

Put a cap on there, some dialog on the cap and tighten that thing on and you know don't take it off again because most of the time you're not going able to get the Schrader out. What you end up doing is just replacing the whole pork recover. All the gas pop it out put a new port on there or I'll plug it up and there's plenty of other high side ports. It really doesn't even need to be there.

You can get on the liquid line right there. You can get basically on the discharge line at that valve. You know there's a million other places where we can get high side pressures on this thing, so most of the time that port doesn't even need to be there, but I can't get in there with the camera because it's not picking it up, it's not focusing, but It's got micro bubbles popping out of that Schrader.