In this class, Bryan teaches the Kalos techs about Residential Low Voltage HVAC Troubleshooting. Low-voltage electrical operations confuse quite a few technicians, so Bryan covers basic circuits and clears up some misconceptions about the terminology we use.
Circuit boards seem to trip up a lot of techs. Unfortunately, every circuit board has a different configuration, so it is difficult to teach the topic from a general angle. Instead, we can isolate the circuits and functions of a circuit board. Then, we can explain how those fit into the basics of electronic applications.
Techs will get a solid understanding of a system’s electronics by learning about the sequence of operation. Each system has specific terminal designations, and the tech should know what all of those are for. For example, the Y circuit on a split-cooling system energizes a contactor and is associated with the compressor and cooling. On a two-stage residential split-cooling system, both Y1 and Y2 must be energized for the system to function at full capacity.
However, the Y circuit is not necessarily associated with cooling on a heat pump system. So, saying that the “cooling call” is on the Y circuit is NOT accurate for all systems. During a cooling call on a heat pump system, you must energize O (usually orange) to enter cooling mode.
Consequently, memorizing circuit boards and electronic applications can be difficult for technicians who rely on memorization and don’t have a solid grasp of theory. Techs can, however, memorize the four basic components of the refrigeration cycle (evaporator, compressor, condenser, metering device) and the basic circuits on the low-voltage side for heat pumps and straight-cool systems.
Even though we say that many electrical failures are “shorts,” not many people know the true meaning of the term. A short happens when a circuit takes an unintended path. To diagnose a short, you have to know the intended path and see where the circuit tried to take a shortcut and bypass the load.
When the current bypasses the load, it experiences little to no resistance. Blown fuses and tripped breakers on the transformer indicate shorts. A fuse blows when too many electrons flow through it (the current is too high).
Another type of short that doesn’t involve a blown fuse. When wires rub out, the current may bypass the switch but not the load. We can refer to these as “switch-leg shorts.”
We also tend to misuse or overuse the word “common.” “Common” merely refers to a place where you connect things together. For example, the C terminal on a capacitor is the common point between two capacitors. On your compressor, the common terminal is the common point between the two windings (run and start). On a low-voltage circuit, common is the opposite of the hot side (24v); common if often connected to ground.
“Open” refers to a break in a path that may be designed or undesigned. For example, an open switch is designed; when a switch is opened, the electron flow stops. So, electricity stops flowing through the circuit, and the system components on the circuit shut off.
When using a multimeter, it is a good idea to set your meter on the ohm scale first. Voltage goes to the leads and will start looking for a path, so you can test your leads by putting them together. When using the ohm scale, make sure you differentiate between no ohms and infinite ohms. You can also test your multimeter by setting it to the volt scale and testing the leads on a known power source, such as an outlet.
As always, wear safety glasses when working on live circuits.
Check out TY’s video on Analogies for Magnetism here:
Read all the tech tips, take the quizzes, and find our handy calculators at https://www.hvacrschool.com/.
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These are the most valuable videos on YouTube to date for hvac technicians
Yes this guy is a good instructor. What school is this? I did auto/diesel at UTI in sacramento and those instructors too are great. This was a great refresher video. Thank you!
does this dude like hearing himself talk? lol
7:33 he says if you haven’t read the rack manual… what is the right spelling for the rack manual? Thank you I want to read it.
If I were a younger man, I would come to Florida to take your course!
this is amazing
70% of ng furnace issues are related to installation.
Your information is great but you talk too much. Just get to the point. I spend more time fast forwarding your videos than enjoying your videos.
very nice sir..and a lot of thanks to you for sharing with us…
Common is return path without common there is no path no current !
Common is neutral
This is very basic stuff. I guess i thing everyone already knows about.
this is a great presentation, keep it coming
As a mid level tech (8years exp.)I think you hit the nail on the head.Sometimes as technicians we complicate things further.I’ve been watching sequence of operation by you and Already this week it has cut my troubleshooting time down.Instead of guessing you go thru the steps of operation and BOOM there’s your problem.THANK YOU #blackICE
Hi. Can you please make a video of the proper way to flush a line set from r22 to 410a. The system is in a condo and is imposible to replace it. Thanks
This YouTube channel always makes the best content hands down
I'm using YouTube to straighten out my HVAC that a tech screwed up and it's a good chance he learned on your video.
you guys rock
this is top notch content. thanks.
UNBELIEVABLY painful to watch and hear
This teaching method and class interaction sucked on a galactic level
🔰🇺🇸 — Ah…you just t-shoot to board level by process of elimination and if needed just change the board.
Thank you
I had a short one time in an old house where everytime I would touch the handle for the hot water I would get a jolt. I turned the breakers off one at a time until it stopped doing it and I found a neutral wire loose in a light fixture in a bedroom. The current had found a path to ground through a water pipe some kind of way. Everything worked fine as long as you didn't stand in water and touch the hot water valve.
Short to ground vs short to common?
You are in Arizona because you said Ron.
What company do you work for?
Love it this videos help a ton. 🙂
Can be hvac translate to speaking of indonesia
Idk how you have time to do these videos and run a business. I barely have enough time to watch all your videos! Lol
How do those twitchy/fidgety people in the front not bother you?
Great content I learned a lot from this video very grateful for your heart you have for this trade and your willingness to teach with amazing attention to detail. I hope to be as wise as you or even 60% lol but I really want to be the best at what I do. Watching your videos helps me very much
i think every tech should learn before hand before troubleshooting anything OHMS LAW ,,,,,get that down it will help you young guys a lot ,,,your welcome lol
havent watched the whole video yet but i will ,,,,from the top of my head as far as circuit boards we where told in class ,,,,if you have voltage to it and not out of it ,,,its a bad board ! now lets see the vid here ,,,,,