Low Voltage Diagnosis Basics w/ Bill Johnson

(Audio Only) In this podcast, Bill Johnson shares Low Voltage Diagnosis Basics and his practical tips to make low-voltage electrical diagnosis easier in HVAC work. Bill is one of the original authors of the Refrigeration and Air Conditioning Technology manual.
A common issue that techs have in low-voltage diagnosis is that they overcomplicate the issue. Techs should take the time to trace out the system and see where all the wires lead. The techs can be more effective if they know a system's components and those parts' relationships. During diagnosis, some techs also don't allow themselves to use their hands. Bill recommends using an alligator clip on the system as you "walk your way" through the whole circuit for diagnosis.
"Short" is a commonly used term. A true "short" occurs when the current takes an undesigned path with almost no resistance. Some of the things that we casually call "shorts" are actually open-circuit issues where the current doesn't make it all the way through the circuit. Real "shorts" include shunts on the load and blown fuses. If a fuse blows but everything else in the low-voltage circuit seems to be operating fine, check the amperage at the transformer outlet.
Electronic boards give techs a lot of trouble because they seem complicated. But, in the end, these boards are just switches where a hot wire goes in and a hot wire goes out. (The common wire goes straight through the board.) The board is nothing more than a distributor of voltage, and the best way to work on them is to simplify them. You can simplify electrical boards by figuring out the inputs, outputs, and sequence of operation.
Bill also discusses:
Grounding on one leg
Connecting to ground
"Probing" the hot side
Measuring amperage on a thermostat
"Spark-tricians"
Commercial vs. residential low-voltage electronics
Stripping wires
Read all the tech tips, take the quizzes, and find our handy calculators at www.hvacrschool.com/

[@dburto13]

Very helpful and informative. Thank you

[@jericosha2842]

That alligator clamp on common and walking down the circuit is such an awesome way to do this. Thank you, I'm going to start doing this immediately.

[@integrity5264]

great topics, thank you

[@chriscooley906]

I loved this pod cast and man to hear it straight from bill was awesome, I love the BTU BUDDY articles your so lucky to get all this first hand knowledge can’t thank you enough for sharing. Holy cow guy 10 kids run a business and do vids and podcasts teach, your pretty amazing dude keep up the great work !!!!

[@twisted8956]

Always love the control side of hvac hate everything else

[@jimgill5706]

Thanks for all the BTU Buddy stories Bill.

[@jimmyung3212]

Very good information and explaination thank you.

[@robertsabur564]

Great Podcast

[@Barracuda48082]

3amp poppit breaker..usually has 1/4" quick connect terminals

[@acservicedaytona386portora3]

Like this video so much...I bought the book.......👍 ...

[@barrettjamison6259]

I appreciate your pod cast found it very educational can you do something on economizers been running into them and having troubleshooting and vacuum and system tools

[@carlosmccullough7106]

Excellent knowledge

[@jimmyflinn8718]

Great video

[@HVACS]

Glad you enjoyed it

[@toddmediumwellingtoniii478]

where can I get the refrigeration manual?

[@geraldschilli8870]

Need video, not just audio.

[@leonardlewis5586]

GOLD

[@rj.parker]

Nothing like some diagrams when talking controls. And then some lab experiments for the real beginners. Even then it takes a good understanding of the circuit to avoid shotgunning the problem.

[@toddmediumwellingtoniii478]

is common wire the neutral wire?

[@theackid7887]

Todd Medium Wellington III it acts the same way

[@AGON17]

Same thing just different name. Common for low voltage, neutral for 120 ,

[@jasonrhyne299]

What do you think is the most important thing you have learned so far that you could teach us

[@barrettjamison6259]

Oh yeah I to have a lot of kids hang in there Yahweh won't give more then can handle I have 7 keep the faith