This video is brought to you by spore'ln quality, integrity and tradition. Okay. So today my this is an interesting service call. I've got a, we did a repair on this walk-in freezer.

Last night we had an emergency overtime call and we found that the system was completely out of gas. We found a major leak at dual pressure control. We replaced the dual pressure: control back into down, got the unit running and then I came back out to do a follow up this morning and the box was not down to ten. So let's go up onto the roof and see what we can find right now.

The box is currently at about 30 degrees. My evaporator fan motors are running, but it's just not cold enough in here all right. So now we're up at the rack, and I've already got my gauges on this and I already know what's happening, but this is an interesting problem and I kind of want to point it out. So we are off on low pressure right now.

So if you notice my low pressure with my gauge as the compressor is not running, my low pressure is sitting at 30 psi. My high pressure is at 174. Okay, my system is calling my temperature controllers set for negative 10 and my solenoid valve is open, but my pressure on the low side is not rising any higher than 30 psi. If we look at the low-pressure control set right around 30 psi, let's see to cut out at like 15 psi.

What is happening here is our pressure. Our pressure is essentially aren't equalizing, but they're. Not the low pressure is not coming up high enough now mind you, the box. Temp right now is like 30 degrees, so we need to adjust this low pressure control, blower, okay, first off the one thing I want to point out.

I've said this before you can never trust these numbers on a low pressure they're. Just the guideline get you in the general area, you always adjust by turning the system on and off and seeing where it actually turns on, but that's not even a real pump. The biggest problem here is that down at my evaporator, we have a pressure limiting expansion valve okay and we are running 404 a so the pressure limiting expansion valve it's the power head on the valve. It has a are Ralph zebra, Paul charging it okay and the pressure limiting expansion valve is there to reduce the suction pressure, coming back to a compressor on a hot pulldown or on a startup okay, it acts similarly to a CPR valve, which is a crankcase pressure.

Regulating valve, I am NOT a fan of using a pressure limiting charge. Okay without the system being properly designed and and even scoreline says, so. The pressure limiting charge is not always a perfect solution for your situation. If you do have pot pull down issues where you have a heavy load on the compressor, what can happen is you can overload your compressor? It can run high amps.

All kinds of stuff can happen. Okay, and that's typically, we see that on. Well, I mean it could be a special use situation where you have. You know freezer box that basically hot product is loaded into it or something done, and that could be a hot ball done and you can overload your compressor so by putting the pressure limiting charge on there, it's reducing the load on it, and essentially this isn't the Exact numbers, but in a nutshell, if you have a pressure limiting power head on this particular expansion valve, it's going to limit the suction pressure to about 30 to 35 psi notice, our standing pressure about 30 psi.

Okay and my pressure control set for a belt. Thirty and some change okay, so we need to adjust this pressure control a little bit lower, but you got to be cautious and now we're gon na watch. This thing operate so running on right now. My head pressure is going to build so the solution here or the problem here was we changed this pressure control last night and because it was super late at night we didn't pay attention to the fact that they had a pressure limiting txb, and I came back For a follow-up and just notice, so the box you know is still just I can hold it up, but what happens likely last night is: is the box actually pulled down in temp right a bit because the the product in there that has been in there all Night is frozen, okay, but the air temp on the box is still in the well.

Let me step on over here, and what we're gon na say is: is that so it ran until it went into its first defrost more than likely, so it's not that the system won't run. It's just that, once it pumps down and shuts off, it's gon na have a hard time coming back on, so the system more than likely ran until it can't went into a defrost and then, when it came out of a defrost, it had a hard time. Turning back on thus why the product is frozen, but the air temp is PI the temperature in the box. He is warm enough to bring the pressure in the system up to turn on the pressure, and so even if it was set at 30, psi 30 psi.

In my opinion is a little bit high on this control, but one of the dilemmas you have with a scroll compressor is they don't like to pump down to really low pressures and what you'll notice on a scroll, compressors, you'll notice, short cycling, so the newer scroll Compressors when they shut off, they have an internal pressure relief and the pressures will equalize if it gets too low. Basically, okay, because the compressors they don't operate properly when turn. So I'm not a super expert on that you, but what I'll notice is, if you have the pressure control set, you low, it'll pump down and then you'll hear it's like a bleed off. Basically, the pressures will equalize out inside there's like an internal pressure relief and then it'll short cycle it'll happen.

So if the pressure control sets you low, it'll, pull down and then turn back off, pull down and in turn, hopefully the house'll remedy. They have a service bulletin out there, where you put a time, delay relay on these things and it basically helps a little bit. But you still have to be careful about setting these pressure controls too low. So it's kind of a fine line about finding that happy setpoint.

So my solution for now is we're going to adjust the pressure control like I did we're going to get the unit running and I do have to come back because, even though we change this pressure control because it was leaking that sucks a line accumulator back, there's Oil all over a two, so we're going to come back and change that suction line accumulator back there we're gon na change the dryer. We didn't change the dryer last night. We just pull the back again. It was super late, so we're gon na change.

The dryer put a new sight, glass I'll, go ahead and change that more than likely just change the power head on the valve and get rid of the pressure limiting, because in this situation here and again, you can't do this on every single one. Some places may need a pressure limiting TXV, okay or a crankcase pressure edgar, but we don't have really hot pull downs. This is just a standard general product, walk-in freezer they bring the product and frozen. It does a couple defrost a day, there's only one person in and out it's not like, they leave the door open and bring product in.

So we don't need a pressure limiting valve on this and also two. So i adjusted this pressure control. Basically, I verify to have a shutting off at 5 psi and turning on at 22 psi, but basically, like I said, the numbers are just a guide, so you pump it down, watch a turn-off and then, if it doesn't turn off where you want, you adjust it Accordingly, so basically I verified, so if you look at mine when I have it set right now, basically, it's hard to tell, but it's below 20 is it done in the cutout is like just above zero, but the actual pressures is 5 and like 25. So these are just a guide.

You never just leave it. You always adjust it to verify calibration. Okay, cleaning, a refrigeration rack today - and you know, like you see in my other videos, I always like to open up the panels to make my job easier. Instead of trying to fight it, so this particular rack pulls up from the bottom blows out the top okay look at this wiring by the way to the previous company.

Look at this spaghetti wiring. This is like a lamp cable. I mean this is not even rated. Look at this coming into here old conduits sitting here, but look at this one's the kicker look at these wires.

They drilled two individual holes for these two wires when there's a rubber grommet right there. What idiot did this? I mean? That's that's just nice, so anyways we're cleaning using a Viper heavy-duty, cleaner, a really great degreaser. I like it and then I'm using the coil wand. This is the Calgon gun and it has this coil one.

So you can spray straight down. So soon we can get to, I usually go at it with the coil gun set on the lowest concentration. So he is an Edward and I usually do a pass. Let it sit and then I'll do a full-strength go on the highest setting.

Let it really get in there and push the stuff out now when you go in the higher setting that a it goes really fast, you got to make sure you rinse it off, because it's a real high concentration, even though I'm rinsing from the top down. So I'm pushing the dirt out the opposite. You know the right way, basically the opposite way here, for I'm also going to spray the cleaner on the bottom sidekick just to help penetrate some area. For me not see up in here, it's like really caked in there and check this out.

So the way this rack is designed. There's a drain pan right here to keep the water from falling on the compressors. That drain pan is full of mud and everything that I'm washing off is getting stuck in that drain pan. So when you're done, you've got to put your hand in there and pull all the big chunks out where, when it dries up, it's just gon na suck right back up onto the condenser.

You got to think. Logically, when you do this, you don't just be a lemming and go in here and wash coils. There is an art to this to doing it proper. This thing is the lifesaver, I'm gon na put it on shower mode, so there's obviously a lot of foam and a lot of water.

We got to let everything dry up and drain out, we'll try to wash it out, but I'm gon na show you guys that that drain pan. I was talking about okay, so right up in here right there is the drain. Pan I'm gon na stick my hand up in there and grab a handful of crap and you're gon na see through that mud. So if I don't get all that out, it's just going to suck right back up on that coil we're gon na pure mud, pure mud in there that's crazy.

So we got to get all that stuff out. Got ta be thorough, okay, so I'm done rinsing. For now I got ta just I tried to wash out as much of the stuff. This rack doesn't have really good drainage, but it is kind of draining over here I wouldn't be the least bit surprised if they have water leaks but we'll find out, but yeah.

So I'm just going to let everything kind of dry out and start assembling it slowly, while I'm letting the stuff dry out for the most part, it should be safe, but every once in a while there could be electrical shorts down here. You know like stuff. Could that water could get in there and they might have a wire nut? You know too low to the ground or something so you just got to watch it. We're going to turn everything on slowly, we'll just inspect as much as we can make sure we don't run into any problems where the part number is, but I'll put a link down in the video show.

This thing comes in handy and you can plug it into you either or fills up quick, but you know I can look at my giant shot bell tolling. Do something crazy, this one I just carry in my truck. I don't carry my giant shotgun in the shop. So while that's running, I'm gon na go ahead and power, this rack up we're gon na.

Do this very slowly turn on main power and then we're gon na do one breaker at a time and make sure the system comes on and runs and we have no shorts one thing at a time. So first thing we're going to do is probably convince our families watched all the condenser fan motor cycle up no short turn this off and I'll. Let the condenser families actually run for a few minutes just to get all the water off the coils, because we're still backing it right but turn on our next system. Let's go with system, he gives an Edward some East.

I don't know what that control. Oh, it's an ice machine, condenser fan motor system, half that's another ice machine. Condenser fan motor. Those won't turn on and sell the ice machines on.

I think this is the mini split down at the end of the rack power. No, that's already running systemc. That's the beer walkin, so it's not running because it's got a call right now. So if I waiting for the time control just turn on a minute there we go, we got a sight glass in the back.

We're gon na watch it until the site. Glass clears up, it is a low temp coil, so the evaporative ammeter has got a gate. The coil has to get cold enough for the background to turn on, so it might flash in the beginning so by cycling. These one at a time or reducing the load on the building, that's very, very critical.

If you have a really old building that has an older electrical system, newer ones, it's not as critical, but it's still good to just have stage the load. Nice and slow system be, as I walk in the freezer with that run, for a few minutes and a is running site classes violently flashing, but give it a few minutes last but not least, system deep and we're gon na set all the defrost clocks. And then I'm just gon na keep that coming out. Okay, it's not gon na be shiny, clean.

I can't I mean yeah, some of that dirt might get sucked back up, but I can't I can't spend all day here. I got the bulk of the water out. Everything's running I'm gon na start just making sure all the site glass is clear and then start picking my stuff up and move on to the next thing. One of the last things is, I'm just you know letting everything run.

I got all the panels put back on, but you got to rinse all the big chunks of stuff away from the rack as much as possible, because again as soon as the water dries all the dirt all gets sucked right back up, you'll just be basically wasting Your time so do your best. You know be thorough, like this all right, so that was an interesting one and honestly right when I walked up, I kind of had a hunch what was going on because we had another tech out there change in the low pressure control, and it is a really Easy mistake to make, if you don't understand some of the components that are out there, such as that pressure limiting expansion valve okay, so you know, like I said, even spoilin - has it in their documents for that pressure, limiting power head actually, because it's just the power Head that makes it pressure limiting, but spoilin has it that you know that is only meant to be used in certain situations. In my opinion, it's better to use a crank case pressure regulator. That's an actual CPR valve.

If you need to you, know, regulate the pressure. Like that, because of like a hot pulldown situation or something, but sometimes you can so you know, but in that situation you know you you have to understand, that's why you know I've mentioned before that. You have to understand the basic principles of refrigeration to be able to work in this stuff, and it's these kind of problems that'll really make you scratch your head. If you don't understand those basic principles, you know and something to think about too, is you know, with a system using a low pressure control like that there's you know a couple things that can affect that low pressure control and the Box temperature is one of them.

Okay, what what you should set it for is what I'm saying the Box temperature and the ambient temperature, because, knowing that refrigerant reacts to temperature right, so I didn't given temperature. A refrigerant is a certain pressure. So knowing that you know for or for a at you know, we can look at the pressure right here and 404. A at you know negative 20 degrees or negative 10 degrees is going to be a certain constant pressure.

But if you have really cold temps outside you know it can reduce the amount of drive that that gas has when it. You know when it flows through the system, the driving force would be the ambient temperature and then the box temperature pushing all that stuff through the system. So you just got to understand those principles. You know that the gas is going to react to temperature, whether it be outdoor ambient and or box temperature.

Okay and in this situation, because we had a pressure limiting expansion valve power head, it wasn't letting the pressure in the system essentially equalize like it should have been. Okay, if you had a normal expansion about power head, so we had the pressure control set to high and, like I explained in the video it ran, because when we left, we know that the Box temp was coming down. We didn't watch it come down to negative 10 or anything, but we watched it come down a significant amount from where it was when they called us, which was like 55 degrees or something crazy, because the box was down. So you know we saw it run, but just from looking at everything, in my opinion, more than likely it ran until that first defrost and then, when the when it came out of that first defrost, it didn't come back on so then I sat there for about Three hours until they called me out and or until I showed back up to do a follow up.

So you know those are some interesting ones and then obviously the coil cleaning. You know, there's not really too much to those I'm gon na have links down in the bottom of the show, notes for all the you know, my vacuum and the coil gun and all that fancy stuff, because you guys always ask about. What's the part numbers for those different things, so I always throw them down in the bottom of the show notes of the video there'll be links yeah, you guys and that's pretty much it okay, so I'm gon na bring up to the customer. We haven't done the repairs yet, but I will bring to their attention and submit the quotes and they'll approve it.

They're really good about that stuff, so they'll prove us replace and that accumulator will change the dryer we'll put a new power head on the expansion valve. So long as I don't see any corrosion or anything like that on the body of the valve, we'll just change the power head, it does have a strainer on it. So we'll pull the strainer out, make sure it's cleaned. We're gon na go and put a new sight glass on there, because the sight glass is pretty weathered and I think that's it.

Oh and the other thing was - and I remembered when I watching the video and editing it down. Is I'm gon na go ahead and make sure I tighten up that uh that electrical connector on the bottom of the pressure control, so um really appreciate you guys taking the time to watch these hit me up in the comments. Let me know what you think give me advice. Give me feedback, questions, feel free to send me an email at HVAC, our videos at gmail.com and other than that guys.

We will see you on the next one: okay.