This video is brought to you by spore'ln quality, integrity and tradition. Today we have over time service call it's about 4:30. In the afternoon I think maybe five o'clock we've got a walk-in cooler. That's not maintaining temperatures right now when I walked up.

The condensing unit was not running it's on their back dock and then, when I walked in, I literally just heard temperature controller call in the solenoid valve open one of the first things that I notice it's not, but the evaporator coil is filthy. This is a ceiling mounted coil, so it draws the air through the fan, guards and blows it out. So oftentimes people will see the vapor to quantum think it's clean, but it's actually filthy. So you try to see in there.

As Dave would say, it's a Fargo bug, but I don't know again. I have a feeling because the moment that I walked in here I heard the solenoid valve call that we're gon na have a temperature controller issue. I have a feeling it's satisfying too early. Maybe it's just a Russell condensing unit out here.

Let's see what we got going on, I got a lot of wind noise there, but we've got a clear sight glass. So we're going to take the cover off and gage up check out the defrost clock go through the whole thing. One thing just kind of do: a visual look at that piece of cardboard back there, today's a really windy day, and I wonder how easy it is for that. There's another thing that I don't like it was really windy and really hot day and that's sitting right.

There all right well we're still gon na go through everything, so the units satisfied again, I'm gon na put a thermometer in the box, but I'm still just continuing my visual. The unit says almost the correct time, so I don't see a problem with that. It does have an excessive defrost, though, for a walk-in cooler way too much defrost. We want about 20 minutes at the most for a walk-in cooler.

You can't shut a walk-in cooler off for 40 minutes at two o'clock in the afternoon. That's no bueno! So that's not good. Either we turned on at 39 right out. 40 degrees is what it turned on at refrigerant.

Pressures are not looking hideous 39 right now, not worry about supply temperature, but inside the sky. We call this. Our target. Temperature is forty degrees.

Our target TV is ten degrees, minimum condensing temperature minimum condensing pressure. We're not going to worry about that right now, because so we are running a clear sight: glass we're looking good there, we're just looking at our a box stamp see what we turn on in effect. So I thought it was a thermostat issue because, but now it's not looking like it condenser fan motor number. One is running point four and is allowed to run point four three.

So we're good on that that your fam boarder number two is allowed to run. One point one amp, so I give here like a bearing noise earlier coming from one of those motors but they're both operating correctly, so we're just gon na keep watching all right. This thing is cycling where it's supposed to be it's bringing the Box down to 36 degrees coming back on at 39 degrees, so don't see a problem with the temp control. At this time, refrigerant pressures looked at sight, glasses, clear we're, actually satisfied right now.

Two things, I think, might be the problem that piece of cardboard, that's right there could have been sucked up against the condenser is a very windy day. We have the Santa Ana winds here. We had 70 mile an hour, winds, gusts and they've kind of died down, but stuff blows around like crazy. When that happens, we have an auto reset dual pressure control.

So if it did go off on high head pressure, it would reset itself. Second thing is: is right around the time that they called me to ish is when the unit would have been in a defrost for 30 to 40 minutes that could account for high temperatures. Also that 30 to 40 minutes in the middle of the day is too long by the way. So we shorten that down we're gon na come back more than likely tomorrow clean the evaporator and then we'll reevaluate everything, but I think we're gon na be okay.

I'm gon na watch it for a few more minutes because we're dropping in temperature significantly right now, it's probably about well. I guess I can tell you what it is, because I have it on my thermometer. 66 degrees right now, when I got here was probably 70s. So I just want to make sure that we don't start flashing on the sight glass like a low charge issue, so we returned next morning and right when I walk up the unit is actually warm and temp again.

It's 41 degrees outside and the unit is short cycling. So it's actually going to be end up being low on charge and what's happening is the head pressure control valve more than likely is bypassing, so we have a cold liquid drain coming out of the condenser. We have a warm discharge line and what's happening is, is it's trying to bypass the condenser or essentially flood the condenser, regulate the flow coming out of the condenser and then feed vapor refrigerant? Don't let directly into the receiver. But the problem is, is that we need a liquid liquid seal essentially, so we need a certain amount of winter charge as what we call it sitting in the receiver at all times.

So that way, if the head pressure control valve ever does bypass, because when it does bypass, it blows vapor into the top of the receiver. So it requires that extra winter charge or the liquid seal sitting in the receiver extra refrigerant, whatever you want to call it. So that way, when the vapor pushes down it pushes the liquid to the expansion valve, because our expansion valve needs 100 percent liquid refrigerant going to it, and we don't have that right now, so the unit is actually short cycling. So we're going to go ahead and add some refrigerant and get the charge correct and then finish going through the unit cleaning it up and all that good stuff.

As you can see, it looks like we're pumping down. But if you look at the sight, glass, there's little water droplets or liquid droplets in there and what's happening is we're trying to this system. Just doesn't have enough of fragrance, so we're gon na start by adding it so the next time it turns on I'm gon na go ahead and put a little refrigerant in there. We're gon na try to get it to where it'll actually run and then, after that point we're gon na have to figure out how much is the correct amount of charge.

So if I go ahead and clear this sight glass today, right now, I will know that we have enough refrigerant for the head pressure control valve to flood. If our temperature only gets to 41 degrees for the rest of the year now we're in San Bernardino, it gets pretty cold. We can probably hit the 20s here, so we do need to add extra refrigerant to the system. So that way, when it does bypass below 40 degrees, we still have a clear sight glass.

So it's an added a little refrigerant to the system right now, all I'm doing is metering. My ball valve we're adding liquid refrigerant, don't want to overload and we're not going to overload it because we're feeding through Schrader ports, it's gon na, be fine still. You want to monitor and make sure that you don't add too much, and you know it's like liquid. Back to the compressor, but in our situation, we're going through Schrader valve Schrader valve and through a low loss hose trust me we're not going to be too much refrigerant to this system right now, so we're just going to keep doing it.

Adding gas until the system will stabilize and start running and then we'll take some temperature measurements once I get it running. Okay, now we're getting to a more stable level. I've added just shy of three pounds of gas to the system and it is actually running now. We have a hundred and sixty six head pressure.

We have a thirty back pressure, that's a 7 degree evaporator we're still low on charge; okay, but we're gon na. Let it run for a little bit and just see what happens: okay, okay, now, you're gon na have to visualize this right now so site. Don't pay attention to the names okay, but suction line. Temp is on the discharge side.

Discharge line 165 degrees, liquid line. Temp is on the liquid drain coming out at the bottom of the condenser, so you notice, my discharge line is 165. The liquid drain coming out the bottom of the condenser right. There is 46 degrees.

So now what I want to do is take this and put it on the liquid line and show you what the temperature is. Look at 83 degrees. Okay, so went from 46 degrees to 83 degrees, because this valve is currently regulating the flow, because our head pressure in the system is below the bypass pressure. The bypass pressure is about 180 psi, and this valve will start bypassing.

So we are bypassing the condenser right now discharge lines. Hot liquid drain is cool. Liquid line is warm sigh class, so I think we might just be satisfying right now. Yeah, I think we're satisfying what we're gon na do is we're gon na go ahead and calculate the flooded charge for this unit.

Now this is an interesting situation. We knew it was low uncharged. I added refrigerant and I cleared the sight glass, but it only has enough refrigerant. For a 41 degree day we are going to calculate flooded charge for a 0 degree day.

That's an extreme low extreme low, probably won't ever get to zero, but we're going to be safe. Okay, so we're gon na calculate for a zero degree day. So we are gon na calculate the extra amount of refrigerant there's another way that you can do it, where you take a heat, producing device pump down the receiver, move the heat producing device up and down, but I want to show the proper way using spoil ends. 90-30, one method which is actually right here and it tells you how to do it.

It's really not that difficult, so we're gon na go ahead. The first thing we're gon na do is we're gon na measure, the straight length of the pipe we're gon na find out the diameter of the pipe which is 1/2 inch and we're gon na count the return bends and then we're gon na. Do some calculations and figure out how much refrigerant we would need to properly flood this condenser? Here's what we know we have r22 refrigerant. Our condenser tube diameter is 1/2 inch.

Our measured condenser tube length is 33 inches. That's the straight section of condenser tubes, the total condenser tubes counted are 48, the total counted returned, bins are 46, our return Bend equivalent length is 0.25 0 and our density factor for r22 refrigerant at 0 degrees. Fahrenheit is 0.1 0. 0.

Now that we have all that information, we could just simply get our calculator and do the calculations. So we have a 33-inch measured tube length and we need to convert that into feet. First: okay, because that's 33 inches and we need a foot measurement, so we're gon na take 33 divided by 12 and we're going to come up with 2.75 feet that makes the calculator math a little bit easier. Then we take the 2.75 feet times.

The total amount of tubes that we counted, which was 48 tubes, equals 132 feet of straight pipe. Then we got to calculate the total equivalent length of our return bends. Okay, so 46 return bends times the equivalent length calculation of pulling 5 0 equals 11.5 feet of total pipe in our return bends. Ok, then, we're just going to add those two numbers together: 132 feet plus 11.5 feet equals a hundred and forty three point five feet of measured tubing, including the returned bins.

Now we're going to take our density factor of our 22 refrigerant at 0 degrees and multiply that times are 143 point five feet and we come up with 14 point three five pounds of extra refrigerant needed, and that is our 22 refrigerant for this condenser to properly Flood at a zero Degree ambient in the wintertime. Now we're not done yet because I cleared my sight glass at 41 degrees. So we're simply going to do this. Calculation again find out what the difference between the density factor number at 40 degrees versus zero degrees and whatever that difference is that's how much extra refrigerant my system is going to need because I cleared my sight glass at 41 degrees ambient.

But I want that sight. Glass to stay clear, all the way down to zero degrees ambient, so hopefully that makes sense for you guys, so we got the fin guards and fan motor blades off. You can't take the motors out without dropping the pan, so we're gon na do this with them. In place, but look at that you know dirty.

That is what we do. Is we brush it off? First then, we'll put a cleaner on there and go through it like that. So we had a hard time trying to brush this through the fan. So I'm still gon na put it back up when I rinse it, but we just hinged the coil.

So now I can brush it really quick and do a better job of just brushing this. This thing is just hammered so this way I can get in here and just go boom boom boom and it's not falling in the drain. Pan I'd rather just fall on the ground and not be as worried about it getting stuck in the drain. Pan that's up, but again, I'm not gon na apply water, yet just because I don't want it dripping all over me.

We're gon na brush the dry stuff off first and then go from there. Normally, I don't want to use any harsh chemicals, but I had to use new bright because this grease is just so thick, so I'm gon na get a rinsed off now. So it's still not perfect, but it's so much better than it was. But this coil is also disintegrating, like the fins are just deteriorating in it.

So this is a mess, we're cleaning these again. You can only do so much. I got cleaner in there. We just rinsed it, but this drain is plugged up right now and it's connected to the other walk-in coil right here, but then it's also connected to their walk-in freezer drain over there what a mess and then it runs out that way all right.

It has been some time took us a couple hours - it's now one o'clock in the afternoon, and we started this morning about 7:30. So it's been taken some time to get this thing cleaned. I had another tech with me to ceiling-mounted coils that were in horrible shape that haven't been cleaned in very long time. So and then it was just like one thing after another, in the middle of that went to go turn this one back on.

It wouldn't run bad disconnect we'll come back and do that couldn't find the breaker to shut off the evaporator fan motors had to unwire it hot. It was just like one drains plugged up so anyways just got the evaporator fans all put back together. Everything's good drains are clear: we're gon na turn this guy on. I had added four pounds earlier for the the winter charge, so that way this unit can run at about.

I think I set it up for about zero degrees yeah, so it can run at zero degrees. Everything is looking good so far, so I'm gon na fire it up and see what happens all right. Now that we've fired everything back up. You can see that my evaporator temperature and or my suction pressure are much better now that the targets that measure quick is getting or giving me, I'm actually meaning.

Okay, and that's because we cleaned the evaporator coil and increase the airflow across the evaporator coil. Also, our outdoor ambient temperature has significantly increased I'll scroll that over right now and you'll see and everything else seems to be checking out. Okay, one quick check. Now we have airflow, I can actually feel it when I walked in the door.

I get blast blowing right down there I mean the box is coming down to temp brilliantly, so we are good to go. Everything is good. Hopefully I didn't confuse the heck out of you guys and hopefully that kind of makes a little sense to you um. You know, one thing to understand is: is that my videos are in the field and they're not prepared you know, so I didn't really go into that thinking.

Hey, I'm gon na do a presentation on a head pressure control valve I just kind of utilized what was in front of my face. So that's why you know everything is not perfectly said and everything, but I think you got to get the gist okay. Now I did do the the calculations out in the field, but then I just came back into the studio rather than showing a piece of paper and just typed them out on a PowerPoint thing and drew the slides up there. Okay, the important thing to understand is: is the purpose of the head pressure control valve the head pressure control valve? Is there to raise the condensing temperature or the head pressure of the system to help to maintain a pressure differential, one side of the expansion valve and the other side of the expansion of the pressure differential across that expansion valve? So that way we can drive the refrigerant through the valve, so it can properly meter the refrigerant and evaporate properly inside the evaporator coil.

Okay. So with that being said, if we have a really cold ambient temperature outside our head pressure or our condensing temperature is going to go down. Okay, because the temperature, the ambient temperature, has a direct correlation between the refrigerant temperature, also okay, because of the thermodynamic principles. I guess that's a big word, but so when the outdoor ambient temperature is really low, then our head pressures really low.

We have to drive that head pressure up, there's a couple different methods we could do. We could do fan cycling. We could do other things too. In this situation we use condenser flooding.

We use a head pressure control valve to flood the condenser block off the refrigerant flow. Essentially, okay and slowly regulate the refrigerant coming out of the valve drive up the head pressure, but when that happens we need extra refrigerant or the winter charge to be in the system at all times. In our situation here our system was about four pounds low on refrigerant. I found a few small leaks, but I definitely want to go back to do a proper leak check, but we got the customer operational.

Okay found a couple Schrader caps that were missing different things. Like that but anyways, so we found that the system was low in gas. So what was happening was the the head pressure control valve tried to bypass, but we didn't have the proper winter charge or liquid seal in the receiver. Okay, and so we were feeding vapor refrigerant into the evaporator coil and we were going off on low pressure because of the outdoor ambient temperature.

So I - and this was one of those situations too - where we have this in California a lot, because we have really high temperature swings so 41 that morning, but then we're hitting 90 during the day. So you know we can come out during the day and everything will be working fine, but then the customer will call us back the next morning and say: hey it's not working. If you don't go out in the morning, you'll go back out in the afternoon again. It'll be working fine, you know and then you're like what the heck is going on.

Well, that's a common symptom. Now in my situation it was a little interesting because the outdoor ambient was really high. I saw that cardboard. You know I was kind of thinking and then the defrost I didn't know where to go with that one and it really didn't cross.

My I mean I didn't think we were low on charge, but we ended up being low on charge. Okay, it was it was. It had enough refrigerant to run when it was sixty something degrees outside, but once they hit 40 it fell off the map. Okay, big picture diagnosis.

You know there's certainly things I could have done to prevent having to go back the next morning, but I was going back anyways, okay, but you know I could have checked the receiver level different things like that. You know, and in hindsight you know you can always do things better, so I really appreciate you guys taking the time to watch these videos. Hopefully you guys get something from them. Keep in mind.

I do live streams I'll be going live tentatively Monday evening at 5:00 p.m. Pacific time as long as I'm not too busy at work to discuss these videos to answer all your guys's questions. Different things like that, there's also a whole slew of new questions that come into the live streams, so just pay attention to my youtube channel Monday evenings 5:00 p.m. Pacific.

Send me an email, hvac, our videos at gmail.com, if you guys have any questions other than that, we'll catch you guys on the next one. Okay.