We have a service call that some cold rails are not working properly. This happens to be the condensing unit for those cold rails, so the complaint is the customer has one two three cold rails that are all turning off midway through the day and then turning on at the end of the evening and running properly. This particular system has a cold zone rack it's covered in grease right now, because of the type of exhaust system that they have that doesn't properly make the grease leave the building. So therefore everything's layered in grease.

So I pulled the panels off the rack. What I'm gon na do in this particular situation, because we don't know what is what usually there's a legend and all my stores. We typically have a legend that try. You know somewhat makes sense, so that way we can see.

So if we look on this right here, someone's labelled CR, CR CR, so this says that system B controls cold rail, cold, rail, cold rail. This is actually in the cooks line. So that's not the one we're working on this right here is the service station, so cold rail system, D, cold, rail system, D, cold, rail system D, the three that they're complaining about is the salad station, the cold side and the hot side cold rails. So that's all system D, as in David and notice system D, is the front cold rails.

If you go into the controls, cabinet doesn't look like there's much going on in here, there's to defrost clocks, they're, actually labeled system F and system G. So that's not s. So we could come through here and look at all the letters there's also letters up here be a C D. I happen to know that this compressor has been pulled out of the rack.

It's not being used anymore, and it's actually this condensing unit over here, because they were having capacity problems, so we added a bigger condensing unit. So this is system D. Currently right now the customer said that it works in the morning of which it's working right. Now that condenser fan motor is cycling on a fan cycle control which is right there, so we're running frosty cold downstairs.

I already checked it, so all the cold rails are working at the moment we are running a clear sight glass, but what the manager told me kinda already led me to what the problem was. He says that it runs amazing, but then it just falls off the map and stops working for a period of a few hours, and then it turns back on in a few hours and then runs for the rest of the night. Well, that leads me to the defrost clock because we actually cycle all these things at night time. So if you look at this defrost clock it's currently about 7:45 in the morning and that defrost clock says 11:00 p.m.

and notice it's about to go into a defrost for five hours, so the defrost clock isn't keeping time. So this is gon na be more than likely gon na be an easier one. So I'm gon na pull that defrost clock apart we're gon na go ahead and replace that defrost clock and we'll go cover off the clock. I did confirm that it has 208 going to it.

That's correct. I went ahead and shut off the breaker, so I can get in here just want to kind of do a little review on this clock. This is a DTaP 40. This is a standard electromechanical, defrost clock uses sets of relays instead of just the mechanisms in the clock that way I can handle higher amperages.

So you can run a compressor through this. If you look at the condensing or the box, it usually tells you contacts 2 & 4, which is your refrigeration. Switch mode, can handle 40 amp resistive load and one-in-three, which is your defrost switch Lake, can handle 40 amp resistive. Also so that's one cool thing about these DTaP 40s.

They can handle a decent amount of amperage this one right here. This is a standard operation. You can change some things. You got to read in the instructions but standard out of the box.

It's gon na operate line. One is going to be power to the clock. The in line is going to be your common to the clock, so one, and in are going to be power in common. Two is going to be the common side of the switch leg for number four, and one is gon na, be the common side of the switch leg for number three, the F terminal we're not going to use that, but you could, if you wanted to the X Terminal is for defrost termination we're not going to use that right now either because we're just working on a simple on/off circuit.

So all that we're going to use we're gon na take a jumper and run it from line one to line two we're gon na apply power to one then we're gon na bring our switch to leg is going to come out of four turn. Our compressor on and n is going to be our common for the clock, so I got the new clock in there. This. The one thing I forgot to mention is this new one.

The DT AV is auto voltage. The old one is the DT MV 40. That was a DT multi volt. The difference is this: one had a switch, you could switch between 120 and 240.

This one automatically figures that out they've got resistors or something stepping down the voltage for the clock. I'm assuming is what's going on there, they're, probably just using resistors, but the clock itself is wired back in. I did it just like. I said I was gon na.

Do it everything's back in there like it should be ours line, one is going to one. Then there's a jumper from one to two, then the switch leg or the switched leg is going to four that's turning my compressor off and then we have our common terminal. We've got line voltage or line two coming into common and then also jumping off of, and so there's two wires going to end common from the breaker and common going to the compressor. So the only leg we're actually switching in this clock is going to be line.

One power and that's coming off of four, so I'm gon na go ahead and apply power. Now we can go ahead and set this clock. So I look at my thing here in a minute. We want this thing to defrost from midnight until 5:00.

In the morning. Shuts off the coal drills from midnight till 5:00 in the morning: that's our defrost! Now so we don't run any defrost throughout the day. This is just to give the cold rails time to defrost. They do have thermostats that turn them on and off.

So they should regulate pretty well, but we just need a lengthy defrost in the middle of the night to go ahead and melt all that ice off. So I went ahead and turned power on, as you can see, it's working off of a fan cycle control. So the condenser fan motors not running yet there. It goes just turned on and we can go ahead and test it to make sure that it's correct and go ahead and rotate the clock.

Click it in to defrost the condensing unit just turned off. So we are working correctly, I'm gon na go and click it outta defrost and we're good to go. I'm gon na watch this thing make sure everything's looking good, but I think we're done make someone else's life easy just because I know this restaurant really well. I went ahead and made a note on here that systemd is outside of the rack.

Then I went over here to the compressor. I wrote not in use up here systemd it's hard to see, but outside of rack and an arrow, pointing back and again not in use systemd. That way. The next guy doesn't come here, trying to diagnose a compressor thinking, there's no refrigerant in the system when in fact it's just cut out so then I labeled over here on the clock, what it controls and actually, when you pop the lid, it actually already tells you What it controls right there and then right here on the condensing unit, put it right there that way, the next guy it's easier for him, so this guy seems to be running okay.

I went ahead and also I used the same box because there's no need to change it for the clock, but I just put a new cover on there that way, the date, because there was dates written on the back of this one when it was installed. Those are gone now so that way, there's not a bunch of writing. It's a new clock. New cover, here's the cold rails in question, so this is one of them right here got some fans over there and all this is just a nice.

You know a cold, wrap and I'll go to the next one. This is their hot side and then right over here we have their cold side, so that particular condensing and it runs all three of those cold rails. So we'll go ahead and recap: I had a service call on some cold rails, not working when I arrived. I spoke with the manager walked in shook his hand, said hey, what's up kind of explained to me, his complaints and his issues with the box and talking with him, I kind of already had a hunch, because he said that the box was what would run first Thing is morning, but then made way through the morning shift.

It would shut off for a few hours and then turn back on towards the eat, meat and run correctly for the rest of the night. So I kinda was already leaning towards the defrost clock. Just with his description, so the you know the more information you get from the managers. We have the easier it's gon na make your fault so went onto the roof, confirmed that it was a defrost clock issue.

I went ahead and replaced the defrost clock and the unit is operating properly. Everything else is looking good. While I was on the roof. I went ahead and checked all their other systems that had defrost clocks make sure that they were operating properly and they were they have the right times on them, also just open up there.

He sees really quick check to see if there was any error codes on in there Lennox units, so the older ones that have prodigy or actually no not a prodigy born to him one in seven boards. So I went ahead and check those for the error codes. You know no issues with those just you know being observant. While I was there other than that, the box is working properly checked out with the manager.

He was cool and happy and everything's good.