So today we've got a service call on a walk-in freezer, not working everything in here it's pretty soft, so it's probably been down for a little while no evaporator fan motors running we're obviously going to need to jump onto the roof. It doesn't look like there's any ice formation going on, so we'll continue this on the roof. This is a very interesting walk in. They obviously built this around an existing structural beam for the building.

It's actually in a shopping. Mall seems very interested okay. So I pulled this panel off. This is my electrical section.

I believe this is my freezer unit. This is the only one - that's not running right now and then come on over here. This is a walk-in cooler and one of the fan motors isn't running. So that's another thing we got to take care of we'll have to get them another family.

So for now we're gon na jump on to this guy right here. Just from opening it up, it looks like it doesn't have power, because the time clocks not lit up I'm gon na get my meter in there and we'll check it. I'm gon na go ahead and check all tidge so for 203 Shoei. So that's a good sign.

We have three phase voltage coming in to the top of the contactor. I don't know that I necessarily see a light on the defrost clock, so the next thing we're gon na do is check the defrost clock we're just going to go across one and n. We see that we have two hundred and four volts, that's good! Now, I'm going to jump over from in 2/4, we have no voltage on n24 and then we're going to go from n to three. We have no voltage on n two three okay, so this tells me that we have about defrost clock the way that this system works.

Power comes in on one and end on this clock, 208 volts comes in powers, the timer motor inside the clock. Okay, then, if you notice this one is one. I know it's hard to see the terminals, but just see this one is one: there's a jumper, this little metal, jumper, sometimes you'll, see you wired. That jumper is jumping over to terminal number, two.

Okay. What that's doing is that's bringing one single source of power in and energizing two common terminals of two separate contacts, so one and three is its own contact. Two and four is also its own content. So what we're doing again we're just bringing a common terminal between the two, so we only have to bring one source of power in now.

This defrost clock works in this way when the pins are in okay, that is refrigeration mode, normal operation. When the pins are out, like you see right there, there's two of them that is defrost mode. When the pins are out, you will have power at your number. Three terminals, so between neutral or the end terminal and three, you will have two hundred eight holes on this particular clock when it is in defrost mode when it is in refrigeration mode.

You should have power between four and neutral okay and the way that this clock works is it will not power. The other contacts when you know vice when one of them's power. Basically, so when we have power to four, we will not have power to three or vice versa. Okay, so again we have got 208 volts between one and n okay, so that means that we have 208 holds going to that clock, powering the timer motor and sitting at the common terminal of both of these relays right here.

Okay, so at any given time one of these relays for this, when this clock is working right, has to be energized and neither of them are energized right now, if we go between three and neutral, we get zero volts, and if we go between four and neutral, We get zero volts. That means that internally, on this circuit board, somewhere, this clock is not working properly. Now, here's a really important thing to think about this clock likely shorted out inside of itself. It's always important to look if it was in defrost mode or if it was not in defrost mode, it's possible that the clock itself caused the problem, or it's also possible that a short in the system caused the problem here.

So with that being said, if we investigate this properly, we were in refrigeration mode. So more than likely, if there is a problem somewhere else, it will only be in the refrigeration mode components. Are you get where I'm going there again? We don't know 100 % sure, but more than likely, there's not going to be a problem in the defrost circuit or an electrical short in the defrost circuit that potentially made this clock go bad. Now again, I still need to investigate more.

We don't know what happened so the best thing to do is to go ahead and turn off power. Ok, make sure that we are de-energized, nothing, nothing, nothing! Okay, so we've de-energize this plot. So the next thing we're gon na. Do you guys can't hear this? But I'm gon na put the meter to my ear and I'm testing for tone.

Okay. So what I'm gon na do is I'm going to test from every terminal to ground and we're gon na see if we get a tone, that's going to help us to indicate if we have a direct short anywhere there's nothing on the number four wire, nothing on The number one wire nothing on the number three wire - okay again I'll, do it again, so you guys can see here I'm testing for Tomomi, okay. That is me touching to the panel. So now I'm going to go in touch to every terminal to ground to see.

If there's a potential electrical short and anything any other wires, now it's not showing up quite yet, okay, nothing showing up yet. My fear is, is that I put a new defrost clock in here and it burns out the new defrost clock. So we want to check everything that we can before we go and replace this defrost bucket. The next thing that I'm going to do again, you always want to be cautious about pushing contactors in I'm gon na push that contactor end.

Now that and turn the system on to see if the compressor starts up to see, if there's anything that jumps out of me, that might be a problem by the end of the service call. I will put my service gauges on this, but at this point I do not see a need to okay because I'm not diagnosing a low voltage bra. I mean a pressure problem at this point right now. It looks to be just a problem in this defrost model and if we look carefully, it does kind of look like there's.

Some burn marks up here in this corner. So what we're gon na do is we're gon na energize, okay and I'm going to push the contactor in. You always want to turn your face away when you push a contact or anything okay, when I did that the unit is ready. So more than likely, we do not have a problem with an electrical component and it's just a bad defrost.

Okay, we want to take this time because I'm gon na I want to tell you guys, from my experience, I've ruined a lot of parts by just throwing them in and not diagnosing. First, there's nothing worse than putting a new defrost clock in and then letting this work out of that new defrost lock. And then you got to drive to a supply house to get one because of something simple. You could have tested just a couple.

Little things like. I just did right now just to see if there was an electrical short okay. So, in my opinion, I've done everything in my power to ensure that there's no electrical short that I can prevent. That would cause this clock to go bad.

So we've checked everything so at this point, I'm going to go down to my truck and grab a new defrost timer go ahead and replace it and then we'll go through the rest of the system. Okay, so I've got the clock, replaced notice how the green light is illuminated. I think you guys can see that right there. If we look at the back of the old clock right, resisters, yeah right well, those little resistors are kinda looks discolor.

It's actually really discolored. On the back of the clock, too, I don't see an actual burn mark. Let's be stare long enough, you can find where the short is regardless. I don't need to know that quite yet, we're gon na do is we're gon na test the clock.

Now now this stab myself, these are these little things that are totally just stab me in the hand. That's crazy Thanks! Alright, let's test from 1 to neutral, someone would discover here there we go. I should say: let's test the one to end: it's not necessarily neutral. It's an terminal: okay, 208 bolts, that's good! That means we have 208 going to the clock to the timer motor okay.

So now we're going to test for to neutral and we have 208 bolts. That means we are in refrigeration mode. Everything is running okay, so because it's in refrigeration mode, we should not have any power going to the number three terminal being a defrost mode. We have no voltage.

That is good, so this is the proper operation of this clock. Okay, the fan terminal sometimes can be used to cycle fans. You typically don't see that very much, at least in my rush phones that I deal with you typically don't see the fan terminal being used. You do see the X terminal, that's a really big one.

Okay, I'm gon na try to paint this picture a little bit easier than usual. Let's assume that we have a light, switch downstairs, simple light switch like you have at your house, someone's standing inside the walk-in and when the unit goes into defrost, if it gets too hot inside that coil someone puts that light switch. What happens? Power runs through that light, switch up to this X terminal and energizes a little real, an side here and tells this clock hey it's hot enough, turn off the defrost okay. We call that defrost termination.

Okay, now it's not as simple as someone using a light switch. There's actually a eclipse on thermostatic device inside there and when it gets warm enough, it closes the set of contacts. Okay, we also have a device down inside that coil called a fan delay and the fan delay. Has it exactly what it sounds like there's a delay when we put it into refrigeration mode, it waits until the evaporator coil gets to a certain temperature, usually about 20 degrees anymore.

It turns on the evaporator fan motor okay. We do that so that way, when we go into a nice, warm defrost, and we have all that moisture dripping off the coil a lot of times. That moisture will hang up on those those aluminum fins on the evaporator bubble and if it pops out a defrost and the fan motors turn on right away, then all that moisture will get blown off of the coil and refreeze inside the box. Okay, so we have a fan the way now some evaporator coil manufacturers have a separate fan, delay and a separate defrost termination, and then some manufacturers actually incorporate it all into one little quick Sun that has three wires coming out of it.

So you're just running a common wire and then, if the coil gets cold enough, it sends that common wire to the fan motor. If the coil gets too warm. It sends that common wire up to here to terminate the defrost okay. So that's all the terminals explained on this defrost time plot.

Now this is not the only time clock that is out there. They all work on the same principle, but sometimes the letter designations might change. That's where it comes in handy reading, your schematics and understanding the evaporator coil schematic, because sometimes the X terminal might be a common wire. Sometimes the neutral terminal or the N terminal might be a defrost termination who knows: okay, there's all kinds of different sequences that you can follow.

I would say, for the most part, the more common style is this right here or the mechanical Paragon clock. That's an 81 45. It can either be a 2 0 or a 0 0 at the end of the 80 145 and all that designates as this whole dish. Okay, that's pretty much it on this clock.

One thing that I forgot to mention is the defrost duration. Okay, we have a defrost clock or defrost timer, and its sole purpose is to put the unit into a defrost. However, many times needed a day. Okay, this particular system requires four defrost per day with a fail-safe time of 30 minutes.

That's a very important designation. Their failsafe okay, most of the time you will terminate your defrost on temperature before the failsafe time finishes. Does that make sense? Okay? So we go into a defrost for thirty minutes a day, but that little clicks on relay that I explained to you called the defrost termination switch inside the evaporator coil is going to sense. The temperature of the evaporator coil in wherever it's mounted is really close to a to the return bends, the copper fins.

Sometimes it's even mounted on the congressman's and the manufacturer has designed the perfect spot to mount it. So that way, when they get to a certain temperature in that evaporator coil, it terminates the defrost okay. So this particular system is temperature and or time term. Okay, so we can tarp.

We can terminate the defrost by simply timing out 30 minutes and then it stops more. We can terminate it by the temperature of the surface where the clicks on relay is mounted in the evaporator flow. Okay. Now so I went ahead and mounted like I said for 30 minute defrost and that's pretty common here in Southern California.

That's all we need for the most part. Unless we have a very problematic box, then we can increase it. Theoretically, you can increase your defrost time to 45 minutes because it's probably going to time out anyways. One thing you have to be very careful about is a lot of people do not understand defrost termination and it confuses them.

Therefore, you go out there and you find that the ex terminal wire is disconnected and wired netid off. So what that person before that, before you did was either they couldn't figure it out or they figured out and just didn't, have time to go back and replace the defrost termination switch downstairs. So they just disconnected it wire knowning, but when they do that they turn this into a just. Simply time terminated one thing that you will see a little bit more on a system where the deep bus termination has been disconnected.

You will see not a lot, but you will see a little bit more moisture inside the bottles. Even though there is a fan delay, you will tend to see a little bit more moisture because it runs longer in the deep runs, typically in a walk-in freezer. The ceilings and the walls get a nice thin layer of like permafrost or or you know, frost on them and when the unit goes into a defrost at the defrost oolong that moisture that's been frozen to the ceiling will start to drift long. Okay, it's also moisture from when people open the doors a lot, but the warm air comes right into the box rises to the ceiling and then freezes okay.

So for the box to properly get rid of the moisture, it's imperative that we have our defrost termination hooked up and we don't have a set for too long of a time and our fan delay needs to be working properly. Also, I went ahead and pulled the cover off the unit, I'm doing a visual inspection. I'm allowed to hook up the smart probes, but something I noticed is that when you shut off power watch the motors and the right-side motor comes to a stop. Instead of a slow spin, that's an indication that that motor is going bad, but at this point I've got the smart probes on sorry.

Fat burner fan motors are running. The box is coming down in temperature. It's going to take a while, I'm not going to stay here and watch the whole thing come down like I said, I'm coming back with some fan motors, I'm confident this will fix it for now and then we'll change the condenser fan motor and make sure everything's Good when we come back so this is the next day now, I'm back out here, I ordered the motors and we received - and I just want to show you guys something you can really see it here, because powers turned off spin this one and notice how it Comes to a slow, stop! Okay, spin! This right, one notice how it comes to a quick stop like just the bearings, are going bad so that one effortlessly spins to a stop. So this motors, not bad, it's just going bad! So that's why I'm replacing this one today.

You can also see that it looks like this right here, the shaft I just wiped it. It's like the oil blew out of the bearings or something because the shaft is covered in dirt and oily substance, and you look at the other one. The shaft is nice and clean, so we're gon na replace this I'm in the process of changing this just want to point something out. You know the two most common nut drivers for motors that on the motors that I work on is eleven thirty seconds and 3/8.

So I keep just a sole eleven thirty seconds nut driver in here. So that way I don't have to run down to my band to get a socket set or anything like that. So if you're doing a lot of condenser fan motors, restaurant refrigeration, kind of work and eleven thirty seconds, it's going to be your best friend for evaporator motors condenser motors you're, gon na use it a lot same thing with the three aides. So just a little tip.

Nitch founders are running always want to check your amp draw it's a pretty basic thing, but you got ta. Remember the point. Eight nine so we're under ham for a lot to run one point one and always check your time. Clock settings just so happened that I came up here.

I didn't go into the freezer. I just came up here turn the cadets needed off it wasn't running. When I got up there, just turned it off change the motor turned it back on and there was no power and I kind of had a little panic for a moment like wait. Is there a problem with his lock? So I checked to make sure it didn't.

Have any blown fuses, nope, no blown fuses, so I went downstairs, walked into the box and I noticed that it looked like they just got a delivery because mind you. I was here yesterday and the box was empty and today it's packed to the ceiling, and then I asked the cook: did you guys get a delivery today and he says yeah I got what time did it come and he says like 6:00 a.m. well right now. It's 11:15 and they never turned the breaker back on scared me for a minute, because I just changed this time clock yesterday and I was thinking.

Oh man, is there still a problem with this mind, you it's fine but just went down. There turn on the breaker. Now we're just gon na watch come down to temp and then I'm gon na change. The fan motor condenser fan motor on the walk-in cooler, while I'm waiting.

So obviously this is our evaporator coil. This system does not use a three-wire fan, delay defrost termination. It has three individual limit switches. One of the limit switches is a defrost termination.

One of the limit switches is a fan delay and one of the limit switches is a heater safety switch. So just like, I said it's just like a light switch. The fan delay is just waiting for someone to flip the light switch to say it's cold enough in here to turn the fans on the defrost termination is waiting for someone to flip the switch saying that it's too hot in here turn off the defrost and then The heater safety is there as a redundant safety in case the defrost termination doesn't work, mind you. These are thermostatically-controlled devices, so the little metal disk inside reacts to temperature, but I use a light switch as a term to make it easier to understand, because, theoretically, that's all that it is, is just a temperature.

Actuated switch really so once it gets cold enough, it does whatever it needs to do once it gets hot enough. It does whatever it needs to do, and if it gets too hot, you know it stops working. So that's pretty much it on this. So right now, this unit actually happens to be in a defrost.

Remind you. If you guys look at this. Do me a favor and tell me how many heaters you think this system has and think about what a heater is. It's basically just a filament inside that tube right there, okay see that greenish tube with the black thing.

It's just a filament inside that's getting hot. So if we have a heater, how many do we have here? We have two total heaters because you have to have two sides to one heater right: power in and then neutral out: okay, so there's one heater on the top and then there's one heater in the drain panel. Now this thing is running in heat mode right now or a defrost mode. So if we just simply grab this check the amp draw, we have five point.

Eight one amps same thing up here: check the amp draw five point: five, two amps, so both of our heaters are working all right. Now we have, let's add another thing to the system. We have this guy right here, which is a drain line heater. It basically is just a warm wire that wraps around the drain line to make sure that it doesn't freeze when it's in the freeze mode.

This warmer wire is typically wired in two four and neutral. Okay, I remember four is our refrigeration circuit, because the theory behind that is is that we don't need the drain line, getting warm when it's in defrost, because it's gon na be warm water dripping down the drain. We need that drain line having heat around it when it's in the freeze mode. That way, if there's a problem in the drain line, it'll keep the water liquefied.

So that way it doesn't freeze until it goes into defrost again. Okay, so that particular heater is wired into four neutral and that's pretty much it guys, it's just the basics of electric defrost on a walk-in freezer. This is our refrigeration side of the evaporator. We have a thermostat.

We have a pump down liquid line. Solenoid valve expansion valve and a distributor all going into the evaporator coil and then the sensing bowl for the expansion valve is running out and being strapped to a horizontal section on the suction line, or you can't see it right now, but it's in there. So, let's do a little recap: we've had a service call a walk-in freezer, not working. When I arrived evaporator fan motors, we're not.

This was on a shopping mall, so I had to gain access through security got them to. Let me up. There got to the condensing unit found that it wasn't running. The first thing I checked was three-phase power coming into the condensing unit.

We had that 208 three-phase. Then I checked the next place, which was the time clock I checked to make sure we had power coming in and we did, but we had no power going out on the defrost or on the refrigeration circuit. So that to me indicated that we had a bad defrost time clock, so I went ahead and replaced that powered up the unit watched it run check the pressures looked good. I did confirm that we had a condenser fan motor that was going bad, so I went ahead and ordered that motor one little tip.

I wanted to give you if you ever do any shopping, mall work. This one has saved me some headaches. I would suggest if you don't have a company identification card a lot of times the shopping malls. They request that you leave an ID with them, while you're on the roof.

Some do some don't, but I see more that do than don't. Okay. What I do is I actually use an expired driver's license if you're anything like me, then you've probably left an ID at a shopping, mall multiple times and then realized a couple days later, that you didn't have your driver's license, which kind of sucks. So that's why I use an expired one and then what I do when it comes time for renewal for your driver's license.

If you have to go into the DMV, I would just say I just lost my license and then you just keep it cuz. If you hand it to them, they want to like cut it up or a hole, punch or whatever just tell me how I lost my license and then then you get to keep the old one. So that's that's a little tip that I use and so that way, if I ever leave an idea to shopping mall, it's an expired one and it's not my normal driver's license that or get an identification card or have a company ID. You know that would be the right thing to do, but I don't have company IDs.

I know do that for my guys, so just a little tip, okay, guys other than that we're good to go.