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HVAC School - For Techs, By Techs

HVAC School - For Techs, By Techs

By: Bryan Orr
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About this listen

 HVAC School is the ever growing online source for real training topics for technicians in the Air-conditioning, Heating and Ventilation Fields. In the podcast, we will share recorded training, tech ride alongs, share challenging diagnostic scenarios. All to help make the industry, your company, and your truck a better place to be. Career Success Economics Personal Development Personal Success
Episodes
  • When 0V Isn't Safe - Short #242

    When 0V Isn't Safe - Short #242
    May 27 2025

    In this short podcast episode, Bryan covers some unique electrical cases: when 0v isn't safe.

    When you measure voltage, you're finding out the electrical potential between two points. Just because there is 0v between one point and another doesn't mean there will be 0v between those points and other points. Non-contact voltage detectors are good tools that measure the flux from the wiring, but they have their limitations.

    A common mistake is measuring voltage across a switch. When you measure 0v across the switch, that could mean there is 0 potential to ground, neutral, or the other leg, but it could also represent a closed switch where power is actively being passed. You need to measure voltage across a load or with neutral as the other point.

    You will also measure 0v when one of the legs of 240v power (with a two-pole breaker) stops making contact. You'll measure 0v between the legs, but that's because one of the legs is open. There may still be a complete path on the other leg; therefore, you will want to check for voltage between each leg and ground, not leg to leg. This condition is particularly common in pool heaters.

    In some cases, the meter isn't working and will read 0 when it's set to another unit setting, isn't on (if an analog), or the leads aren't fully plugged in. Check to make sure your meter is on the correct setting, is in proper working order, and has a good connection to the leads.

    Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

    Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

    Subscribe to our podcast on your iPhone or Android.

    Subscribe to our YouTube channel.

    Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android
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    8 mins
  • Compressor Ohm Mistakes w/ Bert

    Compressor Ohm Mistakes w/ Bert
    May 22 2025
    In this episode, Bryan and Bert dive into the often misunderstood world of compressor testing, focusing on common mistakes technicians make when using ohmmeters, compressor testers, and megohm meters. The conversation highlights how diagnostic errors can lead to unnecessarily condemned compressors and wasted time and resources. The hosts begin by discussing fundamental concepts like the difference between "open" and "short" conditions, emphasizing that a path doesn't necessarily indicate a short circuit—it simply means there's a low-resistance path. They explore how many technicians get confused when testing terminals, mistakenly thinking that normal winding-to-winding measurements indicate a problem. Through practical examples from their field experience, they illustrate why understanding normal readings is crucial before taking any measurement. A significant portion of the discussion centers on proper testing techniques for scroll compressors, which often show different measurements to ground compared to other compressor types due to their design, with windings submerged in refrigerant and oil. Bryan and Bert explain why standard motor testers can lead to false diagnoses when they indicate "bad" at threshold levels like 20 megohms—a reading that would be normal for many functional scroll compressors. They recommend proper megohm meters calibrated to appropriate voltage levels for accurate testing. Key Topics Covered: The difference between "open" circuits and "shorts" and how to properly interpret ohm readingsCommon mistakes when testing compressor terminals, especially misinterpreting normal winding-to-winding measurementsHow to properly check for shorts to ground and the importance of clean connectionsWhy scroll compressors naturally show different resistance-to-ground readings due to their design with submerged windingsProblems with inexpensive compressor testers that give false "bad" readings on functional equipmentThe "redneck test" for isolating a compressor to determine if it's truly the source of breaker tripsThe importance of understanding meter auto-ranging and correctly interpreting readings in ohms, kilohms, and megohmsWhy a reading below 0.5 megohms to ground is the general threshold for concern with scroll compressorsDifferences between megohm meters, high pot testers, and standard multimetersThe misconception that winding-to-winding shorts are common without corresponding shorts to ground Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool. Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium. Subscribe to our podcast on your iPhone or Android. Subscribe to our YouTube channel. Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android
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    35 mins
  • Motor Ambient Rating - Short #241

    Motor Ambient Rating - Short #241
    May 20 2025

    In this short podcast episode, Bryan talks about what the ambient rating means on a motor. These ratings can be found on both condensing fan motors and blower motors. They have Cs in their rating, which represents the maximum ambient temperature the motor can handle in degrees Celsius (like 40C or 60C).

    Heat and overvoltage kill motors, and motors with higher ratings can withstand higher temperatures and last longer in hot conditions. Be careful not to confuse this rating with the insulation class (which is classed by letters and corresponds to temperature limits). You could have a condition where you exceed the insulation's rating but not the ambient rating.

    Air over operations (especially in the case of TEAO motors - totally enclosed air over motors) also play a role. The airflow helps cool the motor, and airflow restrictions like dirt and soil can create conditions that cause the motor to exceed its rating.

    Motor bearings also matter. Ball bearings tend to last longer and withstand higher temperatures than sleeve bearings, but they are noisier. Many motors use sleeve bearings, and replacing a sleeve bearing motor with a motor that uses ball bearings may negatively affect the homeowner's comfort due to the noise, so that's a conversation you'll want to have with the customer and set realistic expectations.

    Have a question that you want us to answer on the podcast? Submit your questions at https://www.speakpipe.com/hvacschool.

    Purchase your tickets or learn more about the 6th Annual HVACR Training Symposium at https://hvacrschool.com/symposium.

    Subscribe to our podcast on your iPhone or Android.

    Subscribe to our YouTube channel.

    Check out our handy calculators here or on the HVAC School Mobile App for Apple and Android
    Show more Show less
    5 mins
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valuable information for techs by techs right on. Perfect title for Podcast. Looking forward to applying for the scholarship. I'm interested in the apprenticeship and learning the trade.

Relevant Topics

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I've listened to a few other hvac podcasts lately and they are painful. This one is actually really really good.

Really good!

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Bryan Orr is a great instructor. He is very knowledgeable. He has experts from various parts of the industry as guests. He goes above and beyond to give back to the HVACR industry. he has helped me to become a better technician. so grateful for the content he provides.

amazing HVACR podcast

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The podcasters are easy to listen to, not hard on the ears. The HVAC & related material are always informative & applicable. I appreciate these audios.

Informative & Enjoyable

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I’m new to the trade and love the way you explain it.
Thank you so much.

Thank you.

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Great educational speakers and great industry information. Would highly recommend to anyone in HVAC industry. Also has great plugs for great industry tech.

Great educational speakers and great industry information.

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