I got a few calls this week and i'm just gon na do some basic teaching on this, because every once in a while, you get calls from people and it can be super concerning it. Just feels like you know, you taught that already or they should have known it already or they're in a band and it's scary. I got a couple of those called this week, which is fine as long as you understand what you don't know, and you talk to somebody about it. They were willing to teach you.

The thing is, if you've been in a van for a little while and then you call me and you don't, you aren't actually checking something like uh voltage, you're checking the ground instead of to the other leg of power, or you are trying to figure out how A safety switch works like a low pressure, switch if you've been in a van for a while or you were trained at all. It means that there's something you didn't understand and whenever you ran into it instead of telling somebody you didn't understand, you just skipped over it because you didn't have to, and then you have these gaps that can come back and and really hurt you when you don't Understand something find it out figure it out if you're super busy and it just crosses your mind like oh, you know what it's not what i'm focused on right now, but i don't know how that works. Send me a text i'll get together with you. Do a training class on it, something like that.

I just want to talk about basic uh. First basic meter use when you're checking voltage. When you check your voltage, your meter is showing you the potential difference of voltage charge so from this end. To this end, it's measuring is there a difference in voltage charge if i'm touching this table in this table electrically they're the same so my meter is going to show zero, zero volts, okay, but we already know: there's not any electricity on this table right.

So there's zero volts, but if i go to a wire that has 120 volts on it - and i check from one lug connection point to the other lug connection point on that wire. What's my meter going to show same wire zero, my meter's still going to show zero now, if you grab that wire you're gon na get shocked, even though your meter told you that there was zero volts there, as your meter is designed to show you the potential Difference in charge between two points: it doesn't care how much electricity is actually there. It's just measuring whether there's a difference between here and here. First things.

First, when you do a safety check when you go to touch anything, i've saved joel's life about six times in the last month from shocking himself. We hadn't yet developed the habit of before you touch anything electrical. Do a safety check to ground so take out your meter and you find out if there's voltage, so if you were going to check if your system had voltage before you touched it, how would you do it jacob? I would check the high voltage wires coming into the bottom of the contactor okay, so your wires against each other, okay, and if it showed zero, i still checking the ground first. Okay, great you're still checking the ground first, so he's checking the wires the two wires coming in to see if he's got high voltage, but if it shows zero that doesn't mean that you're safe to touch anything.

I've been shocked before because i showed up at a job and only one leg of power was coming from the breaker and it was going through the motor and back to the other wire. So i checked to the two wires on the bottom and it showed zero volts because it was the same 120 going all the way through the motors and back. And then i reached out to grab the capacitor and got shocked in order to know that you're safe check the ground. One lead on ground, one lead on the wire, because when you get shocked, you're ground, so you're checking.

Is there any voltage difference between ground, which is what i am and what i'm about to touch? So that's your safety got safety out of the way. That's great! That's not how you check if your equipment's working, so one of my calls this week was that my blower motor is not running and i have 240 going to my motor. I have a g call to turn on my motor and i don't have any amps on my motor and it's not running. It can be frustrating to eventually find out that the 240 you had is because you were checking to ground on one side of your motor's wire and then ground to the other side of your motors wire and they both had 120.

So then the thought process was. Oh, i have 240. a lot of common mistakes that you can make with. Your meter is actually understanding.

First of all, where's my electricity coming from and then where's the first point that my equipment ties into to get electricity. So if you're talking about a motor or a contactor or something like that, you have your equipment, that is the load. And then you have your wires that come off of that and they connect to the point that they get their power from usually one side of. Like a 240 motor is going to connect directly to power and that power is going to be some lug where multiple points of power come in and it goes straight back to the breaker.

Unbroken nothing breaks that power supply, except for the breaker, and then your other side of your motor is going to connect to some sort of switch. You have a blower relay. You have a relay built into a board. You have a contactor, some sort of switch, so one of those legs of power and if you are wondering like okay, my motor is not running and i need to check 240.

Then, where should you put your meter to check if your motor has 240 at the motor? So if you have a x13 module, you have a plug right there right. You can actually at the motor check that in a recent situation with me, i went through the x 13 speed diagnostic, which is just okay. I got a g call and my x13 is not running so probably a failed module like every other time, go to replace it and find out that i still have a failed module, and this was probably this is probably a couple years ago and after running into So many failed modules. I didn't check the obvious, which is: do i have 240 even coming into my module? You take your leads right there at the motor i had 240 coming in.

My transformer was working at 240 coming from the breaker, but there was one connection plug right in the middle of my air handler where one of the connection points had burnt off and i didn't actually have 240 making it right to the motor. So the first connection, point coming off of your equipment is where you check, if that piece of equipment has power. So if it's a condenser fan, you follow the wires back where's the first place that your wires connect on a condenser fan. So, okay, the board relay yep and then the top of the contactor and your your run or your start on your capacitor.

So, where do you check for your 240 in that scenario, yep so relay and the contactor exactly right, so where your wires come in from the motor they first connect. Those first connection points you're, going to check for 240, there you're not going to check to ground on each of those points, you're actually going to check 240. At that same thing, let's say you have a contactor not pulling in. I had a call this week about a system that was flat.

They didn't realize it was flat and they were trying to figure out why the contactor is not pulling in. We have 24 volts yep. We have our call in yellow it's coming in the condenser yep. We have our call in yellow at the defrost board.

Why is my contactor not pulling in and do you have 24 volts on the contactor? Yes, i do so it turns out that a linux system - you have your defrost board. A linux system will send its 24 volts out into the contactor and back to the board. The way that it will actually call the contactor is make a connection through the common side. You will have some linux systems, which i noticed this years ago, will always have 24 volts on both sides of the contactor, the ground just sitting there and the contactor is not pulling in.

But if you check at the first connection, point to your load, which is the side of your contactor you're, going to have zero volts, it's the same hot to ground on both sides, you don't actually have a difference across. You need a voltage difference to actually pull through the way that that board works is it breaks the path back to common from one side of that contactor, and so, when your low pressure switches out it breaks that path to common. It's not going to allow that that common path to make it back to the transformer. So if you're just checking the ground, you might have 24 volts on each side of your your contactor.

But it's not pulling in the proper way to actually test equipment is to find out where those wires from that equipment connect first and check at that point, with your meter for the proper voltage, the only other thing i was going to go over really quick was Just pressure switches, because in training i realized that there could be some easy gaps. I just have a couple of them here. One of them is high pressure. One of them is low pressure, there's a spring inside and so on.

One of these, i'm not sure which one this is without looking at the data tab, we're going to have a normally closed switch and one that's going to have a normally open switch right. Now one of these i'm going to ring out we're going to have a connection through it so which switch? Would that be that's right and so there's a spring in there? That's forcing a path, a connection path between these two wires, so your thermostat calls yellow comes in goes through this and back out to your contactor. On the other side, right, there is a spring: that's forcing two plates of metal together, allowing a path when the pressure gets too high. It's enough pressure to push against that spring and force that path open and then the 24 volts from your thermostat never makes it to your contactor same thing's happening on the other side.

Your low voltage currently there's no path, it's open. So there's a spring. That's doing the opposite job. I got no path through here.

There's a spring inside of here. That's forcing two plates of metal open so that the voltage coming in cannot go out unless the refrigerant pressure pushes hard enough against that spring to close those two plates, and then my voltage can pass through very basic. If you're ever replacing these, you need to read the data tag on them. This one high pressure on here.

It drops out at 325, psi r22. You put this in a 410a system. It's going to be going out in the summer all the time i had this on a pool heater once pull heater pressure switches because pool heaters are not built very well. Often thread ends like this.

That can start leaking over time with vibration. We just pull a high pressure off the van put in a new and the next time that that spa got warm enough to bring the pressure of that pool heater up to normal pressures for 10a. It was constantly going out in high pressure when it was trying to run. I was like it looks like we have a bad switch, pull it out, read the data tag and you realize i have an r22 switch in there.

It doesn't say r22 on there. It just gives you the high pressure drop out 325 to 225, so that's the range that it's going to drop out and then come back in. So it's easy to it's. It's two different scenarios that i had this week that were kind of fun with problems.

One of them is you just have a really bad gap in your training. Like there's a knowledge gap, you can't figure something out. That's pretty basic to any of to anybody who understands it, but you don't yet you're stuck. You have to realize that in that situation, you're going to call somebody and you're often going to get some sort of flack or pushback like.

Why haven't you figured this out or why don't you know it, and the truth is, is that you don't know you don't know what you don't know but, like i mentioned at the beginning, there's a lot of times you run into scenarios that you didn't have confidence In but you ignored that feeling of not knowing what you were doing and just pressed on to do your job. So there's a lot of things like what we've gone over today, that you should have already known if you've been in a vehicle on your own running. Calls but we all have gaps. I still have gaps.

I recently called tech support because i wasn't sure how to prove if it was a blower board or a module that was failed on an infiniti system. I didn't know the proper voltage coming out of the infinity board and the proper wires should check the signal now that i know that i've already ran into another call, since that that i could confirm and diagnose properly. Now that's the piece of information i have because when i didn't know instead of just guessing like i had done years before and being like, it's probably the module, it's usually the module, let's just replace it, and if it's not that, then we'll quote the board. I called tech support and found out now.

I know something. Stick to that process. It's fine to make mistakes like i had a call from senior tech who went out to replace a blower module that i had quoted and he replaced it and the exact same error code came up. So he calls me and he's like.

I think you diagnosed this wrong and i was like shoot. Maybe i did let's go through the steps again. I went through all the proper steps of diagnosing it nope, it's a failed module like well. We just picked this up from orlando like well, then they gave you a failed module, or maybe you put the old module back in during your process of replacement and then there was this awkward silence and a scruffling sound, and then the phone hung up and i Got a text later that oh yeah, i had pulled out the old module set it down by the new one and then grabbed the old module.

Put it right back in trying to turn on the system that kind of stuff, that's fine. We make dumb mistakes and we can get lost, but don't let your mistake be that i don't know something that i should know. That's totally different right. Can we do a training on three days, training on three-phase yeah? We can do that.

I had a three-phase building yesterday on saturday day before yesterday, that the uv bulb had burned out several times and the nest thermostat battery was backup. Battery was not charging and we had been out there several times because an s battery had not been charged and when the system had been installed, they never changed. The um taps on the com on the transformer commercial building 308 is the voltage rating and you have to take your contactor and change the tap from 240 to 308. toy 208.

I was like man. I've never seen that i'll look for it 208 instead of 230.. So your contactor, so both the uv bulb the backup transformer was put in and actually tapped for 240, without even looking at maybe what our incoming voltage was and which which tap we should use. So we had 23 volts coming into our uv bulb and 23 volts.

Coming to our our thermostat, the nest thermostat has a battery that will, when the unit shuts off, will actually start pulling power from the 24 volts to try to charge its backup battery inside the nest. Thermostat. If you have any kind of a voltage drop during normal use, hours on the building, you're going to go well below that 24 volts, sometimes and supplying to the equipment so yeah thanks for watching our video, if you enjoyed it and got something out of it, if You wouldn't mind hitting the thumbs up button to like the video subscribe to the channel and click the notifications bell to be notified. When new videos come out, hvac school is far more than a youtube channel.

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