This video is brought to you by spore'ln quality, integrity and tradition. Today's service call is on a makeup air unit that the evaporative cooling section is not working properly, so we have a captive air makeup air unit. Here i had a service tech here over the weekend. Working on an a/c - and we didn't have time to look into this issue, so i wanted to come up and get it taken care of for him.

So the complaint is: is that the the blower motor, at least what i was told, the blower motors working fine? But we can't get the evaporative cooling section right here to be working properly, so we're going to dig into this and see what we can figure out start by opening up the evaporative cooling section. We can find it nothing too. Fancy. I've worked on this unit before you've got a thermostat terminal block a timer module and water found down at the bottom.

So when this timer module has power to it, he'll have an LED light. Let's open it up, so I'm essentially gon na come in here. Looking at the power without going to a schematic, I'm looking at the power lines, it looks like powers coming in off blue and white White's going to in as a neutral here to the D terminal, and we have three point: 6 volts. That's not nearly enough.

It should be 120 check it to ground nothing and we're going to check every other lake your ground to make sure it's not. This is somewhere nope. We have no voltage inside here, so our problem is not here: we're not being supplied voltage into this area. So we need to trace it back to where the voltage comes from more than likely of problems gon na be inside there's electrical control panel.

So I'm going to put this right back. Okay, so it's like. We have some sort of voltage in here. Just kind of assess, I'm looking to see if I see anything crazy: this is a direct fired, make up air unit.

So this is all the heating section, but we're getting power from this side over here, don't see nothing! Scary! Okay! So, let's look at our schematic here. This is the direct fired, heater wiring and this is the evaporator, even cooler wiring, so we're going to start there and essentially, let's look at our line diagram here, so it tells me that white is neutral. This is 115 volts and blue should be coming off of terminal 11 of a terminal block, terminal 11 and then running down to everything. So let's go into this terminal block and look at terminal 11 and see if we have power.

So if we look inside here, terminal 11 looks like someone's already circled it with Y, so someone's done. Some kind of work on this terminal 11 is a blue wire and then an is our neutral and it looks like if you follow that down. That's going to the evaporative cooler section, so we need to test power on 11 and n is in neutral all right, so we're going to go from 11 to end and we have no voltage okay. So what we need to do is we need to find out if we actually have a hundred and fifteen volts inside this unit right now, so we're gon na start up in our primary transformer up top.

Let's start up here and test voltage, so we're going to go high voltage, 208 volts or 206 and low voltage is 122, so we do have flow 115 volts coming into this. So it looks like we're going to need to look at our schematic a little bit more. So looking at the evaporative cooling schematic, it says the power comes in on 1 & 2. All those are lines so on a 911.

So what we need to do is we need to figure out where in and 11 are getting their power from okay. They did not do a very good job of this, but I figured it out so basically, if you follow the wiring diagram, this is for the direct fired heating section, because this is what's feeding my power. Eleven is powered right here, so basically, this is a temperature controlled contact. Okay, so our temperature controller and eleven gets power from the temperature controller.

So we need to trace that back and then we'll start at the temp control and then see if we have power at the temp control and then work our way back here is our temperature controller, and it says that it gets its power from this control. Old-School. Honeywell and there's our blue wire right down at the bottom. That should be incoming power, too.

Are the operative cooling section: let's go ahead and test and see what we can figure out, put a meter back on, so we're going to go ahead and we'll see if we have voltage present at all to any one of these wires. So we have no voltage present at all to this. If we did have voltage present, then we would check across the contact like so and see, but we have no voltage present so now we need to figure out where this gets its voltage drop. So, let's move back to our schematic again, so if we look, here's our temp art, thermostat or a temperature controller and it gets power from nine which comes all the way back over to seven, which gets power from a pressure switch.

That's a pressure switch there's. Actually, two pressure switches, so seven and six we need to see so it looks like thermostat gets power from the pressure switch, so we needed to pass the test power at seven and we need to test power at six. Okay, so seven is first, so seven is coming out of the pressure switch going to the temp control, so we're gon na go and find the neutral in this circuit, or in this panel right here and then we go to number seven. Seven has no voltage 3.7 volts and then we need to go to six.

Six has 122 volts. So, according to our schematic, our problem is in this pressure. Switch. That's why we're not delivering power to our evaporative cooler section.

So this pressure switch is really a fail-safe for the direct fired heating section, but they kind of just used it for the evaporative cooling section. Well, I mean no I'm kind of rambling and thinking in my head, but essentially they look at high static pressure and low static pressure. You don't want to lowest static pressure because that might indicate it's not running, but then you don't want to highest static pressure, because that might indicate that there's some kind of a restriction in there. So we need to figure out what would cause that pressure switch to open the first place that I'm going to start is my metal mesh filters.

I want to look at them and then see if they're dirty, because that could cause some pressure issues make this unit. Think that it's not working right, so let's go ahead and step on over here to our metal mesh filters, and these things are kind of plugged up, and I really don't hear much air running through these right now mind you the blowers running on this. I can tell so they seem like they're pretty dirty, but just to prove it, I'm going to go ahead and put a manometer on this unit and see what our static pressure is all right. So it's always important that if you're using a manometer you zero it out, so I have both of the probes off and I'm going to hit zero zero it out before.

Okay. So then what we're going to do! Luckily, this unit is really nice and then it has extra ports for you to check air for air pressure. Basically, your static pressure, so we're gon na go ahead and pop these guys on here. So, first off I don't know if you guys can see that I'm going to check total external static.

No, it's actually not total external static. It's pressure drop across the cooling cooling pads okay, so this one is left off and this one is on the other side of the burner assembly, which means that it's pressure drop across the cooling pads and we have 1.38 pressure drop inches of water, water column. Pressure drop across the cooling pads okay, so I'm going to go ahead and set this guy on here and get a differential pressure across the front differential pressure across the burner is 0.72 next thing I'm going to do, and this is just the burner. This isn't mistakin Li said total external static over here.

This is not total external static, so we would have to be on the other side of the blower motor to get so, let's go study, so the next thing I'm going to do is I'm going to test to see which side of the pressure switch is open. I can read on the pressure switch that I have a palm in terminal and a normally closed turn on right here. So, let's see what we do and we test across this, we have an open circuit across common and normally closed. So this side of the pressure switch is the site that is tripped.

So, let's try to clean the metal mesh filters and see if we have an improvement in our pressure drop across the burner assembly and see if that helps us and maybe resets, that pressure switch got to say I have one of these collapsible hoses and for certain Situations, it's pretty nice because you don't have to tear this big heavy-duty rubber, pretty nice supplies. So now my pressure drop across the coolly media goes as low as one point to as high as one point three. We were at one point three before now: let's check the pressure drop across the burner assembly. Put this guy back on point: eight: four: okay, let's test our pressure switch see if our pressure switch, please and our pressure switch still did not close.

It's also possible that we've got something stuck inside the stuck inside the pressure switch, but we also want to open up the blowers. Suddenly I hear it running, but we want to make sure we have a tight belt, so we're going to open that up and check the blower out chair belt is a little bit loose I'll. Tighten that up a little bit seems to be fine, so I'll adjust that belt a little bit tighter. I wanted to test the total external static pressure, so I drilled the hole in the blower assembly, so I can get my static pressure tip in there and so our total external static pressure is 0.5 4.6 right in there and the maximum that the unit is rated For is point seven, five inches of total static pressure.

So we don't have a static pressure problem, so our airflow is really within range every once in a while. We get a spike, but for the most part it's staying below. So the the book that I opened up says the airflow or the pressure differential across the burner assembly needs to be 0.15 2.80 and we're within range. Like I said every once in a while, we have 0.8 182, but then it drops back down.

I'm a pressure. Switch doesn't reset for the most part, it stays under point eight, Oh longer than it goes above point eight, oh, so what I did was I adjusted the pressure switch everything else checks out: okay, the total external statics good. The air filters are clean, blowers tight. I did change the motor pulley a while back, but I set it back to the exact settings.

Nothing's been changed with that, these pressure switches you can adjust them but you're not supposed to because they're factory set and we've never had a problem with this unit before so. With that being said, I'm gon na condemn this pressure switch as being problematic, so I adjusted it temporarily and what I'm gon na do since I adjusted it. I don't want that we're in the summertime anyways, but I'm gon na lock out the gas, because I don't want the direct fired heater to start up since I've adjusted the pressure switch beyond the factory specs. So we don't want anything bad to happen.

As far as the heating goes, so we're going to turn off the heating, lock it out and we're gon na, let the evaporative, cooling run and I'll show you guys the evaporative, cooling, suction, it's 95 degrees outside. So we've got a 15 degree temperature, differential or delta T across the evaporative cooling section now mind you we're having humidity to the building, but it's dry outside right now, so it's not a huge thing, and this is what they want now. This is a non standing. Water evaporative cooling unit, so it's an on-demand.

So essentially it just sprays misters over the evaporative pad for a timed amount of time. Then it turns off. It turns back on to try to reduce the humidity inside the building. So all right! So now you can see that we have a blinking LED, and I could hear it running earlier so so, essentially I made a video on this.

This is the evaporative cooler that froze a long time ago, a big old chunk of ice inside. Here I rebuilt it. This past winter, water solenoid off it's stuck open but anyway. So the way that this works is when the temperature controller calls sends power up to this timer.

This timer controls how long the mr. spray for and then how long they turn off for and by doing that, they control. You know the amount of moisture inside there. Essentially there's no water pump like a normal evaporative cooler.

This one just has on-demand water supplied by this water solenoid off right here and it just sprays and then turns on and off via the timer right here. So you got to go to captive, airs website and they have a document on how to set this timer. I confirm that it's accurate. You really don't want to start twisting on these things.

You set them for the CFM of the unit and basically kind of leave them right there. So and remember, this is not an air conditioning unit. This is not here to cool down the building. This is to temper the make-up air going back in so we're delivering about 78 degree air, but to the building when it's 95 outside, but it's you're gon na, add humidity to the building.

Basically, okay, so we got to be cautious about that. These are only designed for dry climates, all right, well, we're gon na wrap this one up. We're gon na quote a new pressure switch, and I also want to clarify if this was a brand new startup. I might consider adjusting the pressure switch accordingly, okay, but because this unit has been in here for like six years, we've never had a problem with it before I don't trust adjusting on the pressure switch because they're factory set and that's why they put paint on them.

So that way, you know you shouldn't be adjusting these things. Okay, now again on startup, you may need to adjust them depending on all kinds of and stuff, but because this one's been here for a long time, that's why I do not want to leave it, adjust it and that's why I'm gon na shut off the gas. I shut off the gas inside and I shut off the gas here so that way the direct fire heating won't turn on, because, since I've made adjustments to the pressure switch, I don't want to cause any issues. Alright, so that's it! This is that flexible hose.

It's made by Goodyear, I think I got it at Home Depot or Lowe's Home Depot. I think that's pretty nice. I keep one in the truck. I still keep two regular black rubber hoses they're commercial grade ones, but when I can, I use this, especially if I'm on a roof, I'm a little afraid to use this in the restaurant or with hot water, but I'll use the rubber hoses when I'm in the Restaurant or doing hot water, but this thing right here is perfect when you have a short run, I'll, probably pick up another one to be honest with you, because I can keep them in the truck and it's super light.

You don't got to carry up a giant hose okay, so to recap, we had a make up air unit that the evaporative cooling section wasn't working and what I found was that the unit was failed on an open pressure switch essentially okay and it's an air proving Switch, that's essentially there for the direct fired, make abares heating section, but they integrated the evaporative cooler into that pressure switch also, and so the pressure switch was saying that you know the air flow was not correct across the burner assembly, even though it was of which I showed you guys because I proved it with my manometer okay, so I prove that the pressure switch should have reset on its own, but yet it didn't so. I went ahead and adjusted the pressure switch like I said, and locked out the gas heating section until I can get a new pressure, switch ordered okay. I do not want to leave the gas heating section running because I adjusted it beyond the factory specs basically, and we're just talking about a blower motor now in an evaporative cooling section, so there's really no danger in it, but you always want to be cautious about That kind of stuff, you know if you bypass something or if you adjust something beyond the factory specs. You want to be very cautious because you don't want it to be.

You know make you liable for some kind of damage or some kind of injury, or something like that so went ahead and did that we've already ordered the part. I have not replaced it yet, but once we get it we'll go back out and put it back in other than that, that's pretty much it guys. I really appreciate you guys taking the time to watch these videos, and hopefully you guys get something from it. If you like them, if you don't send me an email leave me a comment in the videos, anything I'm always looking for feedback, I'm looking to improve my troubleshooting skills and then I'm also looking to hear how you think I can do things differently, and/or change or Whatever okay, but again, thanks so very much and I will catch you guys on the next one: okay,.