Great video definitely subbing.. almost condemned a drain pan heater because I got OL but when I tested ohms I got 150ohms .. so it was good but I was confused until know it’s too high of resistance to “tone” out
I ohm everything period, I only use continuity to check for breaks in wiring or short to ground. If I am working on something bigger, motor's 25 hp and above that cost thousands of dollars, I am not trusting any meter with a 9volt battery. It's time to break out the Megger 420/2
Ah but is a contactor technically a load or a switch? I argue it's both by design. It's a load, that actuates a switch or set there of. Most text books specify it as a switch or control only. If we really dig into it, it is most definitely a load as well. Ever try and install high current rated contractors in a residential split system with the same voltage coil? Some transformers are incapable of maintaining the same potential difference through the coil as its electrical requirements are greater... Now the real question... Non positive displacement compressors... I.E: Centrifugals. How are they even compressors BY DEFINITION? ;) They're not
When I measure ohm by fluke, it starts with a big number then goes down to a number. Why it does that? (e.g starts with 315.7 ohm then decrement down to 150 ohm)
Motors should be tested for grounds with a meggohmmeter. I have several hand crank styles that can put out 1000volts to ground. They will pick up high resistance grounds that an ohmmeter can’t find, because it tests the motor with its running voltage or higher. It will cause near shorts to arch to ground, therefore testing the integrity of the winding insulation. A meter with a 9 volt battery can’t find these types of defects.
Hello I'm hvac tech. Can't find the answer for resistive load such as heat strip. As you said there is high value on resistance on it such as hot surface ignitor so question is if voltage value stays the same based on ohm law amperage gets lower if high resistance but in heat strip we have higher resistance value at the same our amperage drawn is higher which just contradiction to OHM law. I'm senior tech and train lots of technicians but can't find answers for t this?
As a heat strip warms up, it’s resistance will increase. There is really no way to measure resistance on a live circuit. Any conductor will increase its resistance as the temperature of the wire increases. The molecules get farther apart with heat, and cause this rise. You could prove this by using a torch to heat the strip heater element while an ohmmeter is connected. The hotter the element gets, the higher the resistance will be. Hope this helps.
That's a challenge which limits the overall value of measuring ohms at all. If you can compare your part to a known good unit, that can be helpful. Some compressor manufacturers publish ohm values, but they can be hard to find. Check out my class on electric motors to learn how to ohm out motors at www.hvacservicementor.com
You bet! Go to www.hvacservicementor.com and get Electrical Schematics under the Techflix tab. That's a great start. The boot camp courses are also great resources.
Continuity is a trickster and I'll tell you why. Some meters will only read to a certain value and above that they will give O.L. when you still have continuity. Surprised you left that out. I don't trust it of use it. Spec sheets often don't give the range of operation. You have to 'test' your meter to find it's values. Course that's part of knowing your equipment.
Joe, thanks for your input. On a manual ranging meter, continuity is also the lowest scale range of the meter. If the resistance of the load you are checking is higher than that scale, you will get OL. 200 ohms is common. Beepers will stop sounding around 40 ohms. Some meters may be less. Like you said, you never know what you're going to get. I like the "trickster" description. Very true.
Been in hvac since 2009 and a journeyman since 2012. I appreciate these basic simple tips and information. Thanks man.
Tankyou
This was an incredible video, 👏🙌. I thank-you very much for taking the time to create this video, as well as all of your other videos😀🙌❤
My right ear feels lonely.
Ok so it wasn’t just me lol
Use alligator clips when possible to ohm out a circuit or component. If you press hard or not hard enough....your reading will vary.
What I wish you'd said was: "Continuity just tests Ohms and beeps if it's under about 50 ohms."
Best explanation Thanks a lot 🙏
You are welcome
Excellent. Thank you for the distinction. Thank you for the alert that some pathways have a higher resistance! 👏
Thanks for the thorough explanation and examples of what to use them on. One more gold nugget in my bank.
I want to ask you if you can made a video on ohms that's not making a beep. Thanks Dennis
Thanks soooo much for this. Much appreciated
Great video definitely subbing.. almost condemned a drain pan heater because I got OL but when I tested ohms I got 150ohms .. so it was good but I was confused until know it’s too high of resistance to “tone” out
Great discussion about this topic.
Imagine you are on call with senior tech Diagnosing a bad compressor and ask this question 🤣
Toning a circuit is a carry over from Telephone repairmen tech terminology.
I ohm everything period, I only use continuity to check for breaks in wiring or short to ground. If I am working on something bigger, motor's 25 hp and above that cost thousands of dollars, I am not trusting any meter with a 9volt battery. It's time to break out the Megger 420/2
continuity and ohms so continuity is ohms when u put the meter in continuity mode it just beeps and shows ohms that's crazy I didn't know that
My multimeter does not beep when testing ohms ..
Thanks friendly. That was a darn good video. Bravo 👏
Nice
Good work bro. Don’t know why some didn’t like. Any way keep on Guten Abend
Guten Abend das Gerät kaputt machen
Thanks allot .....great teacher...salute ....
great video,,,thank you
Eric
great informative video - volume very low and hard to hear
Ah but is a contactor technically a load or a switch?
I argue it's both by design. It's a load, that actuates a switch or set there of. Most text books specify it as a switch or control only. If we really dig into it, it is most definitely a load as well. Ever try and install high current rated contractors in a residential split system with the same voltage coil? Some transformers are incapable of maintaining the same potential difference through the coil as its electrical requirements are greater...
Now the real question... Non positive displacement compressors... I.E: Centrifugals. How are they even compressors BY DEFINITION? ;) They're not
It's definitely a load that activates a separate switch. If the coil wasn't a load, it would short.
When I measure ohm by fluke, it starts with a big number then goes down to a number. Why it does that? (e.g starts with 315.7 ohm then decrement down to 150 ohm)
Great video thank you
Thank you.
Thanks 👍🏻
Motors should be tested for grounds with a meggohmmeter. I have several hand crank styles that can put out 1000volts to ground. They will pick up high resistance grounds that an ohmmeter can’t find, because it tests the motor with its running voltage or higher. It will cause near shorts to arch to ground, therefore testing the integrity of the winding insulation. A meter with a 9 volt battery can’t find these types of defects.
Excellent video. Yes I could hear other sounds but not you speaking. My volume was fine on a previous youtube video. Thank you for excellent content.
Rookies use the tone. I hate the tone.
While toning the circuit is often unreliable, testing for continuity does have its place as long as techs understand the limitations.
would be nice if you showed where you were putting your probes ...
Hello
I'm hvac tech. Can't find the answer for resistive load such as heat strip. As you said there is high value on resistance on it such as hot surface ignitor so question is if voltage value stays the same based on ohm law amperage gets lower if high resistance but in heat strip we have higher resistance value at the same our amperage drawn is higher which just contradiction to OHM law.
I'm senior tech and train lots of technicians but can't find answers for t this?
As a heat strip warms up, it’s resistance will increase. There is really no way to measure resistance on a live circuit. Any conductor will increase its resistance as the temperature of the wire increases. The molecules get farther apart with heat, and cause this rise. You could prove this by using a torch to heat the strip heater element while an ohmmeter is connected. The hotter the element gets, the higher the resistance will be. Hope this helps.
I can not get into your website, you need a username and password. Can you help?
Louis
Website was in transition go to hvactraining.squarespace.com/
If you can NOT get a steady reading of numbers on your meter when reading a coil on a contactor , I guarantee you that contactor is bad.
Great content again but I wish you would have also used a Fieldpiece meter 👍
Thank's for that clarification.
👍👍✌️🇨🇦✌️🇨🇦✌️🇨🇦👍✌️
Thanks
Thank you for the explanation!
Glad it was helpful!
Need stereo on voice
How do u know how many ohms you should get when checking for ohms?
That's a challenge which limits the overall value of measuring ohms at all. If you can compare your part to a known good unit, that can be helpful. Some compressor manufacturers publish ohm values, but they can be hard to find. Check out my class on electric motors to learn how to ohm out motors at www.hvacservicementor.com
great video do u have any tips on getting better reading rtu schematics and ladder diagrams ? thank you
You bet! Go to www.hvacservicementor.com and get Electrical Schematics under the Techflix tab. That's a great start. The boot camp courses are also great resources.
Great video
Thanks!
god damn it, it's 2021, get a microphone that records in stereo, captain troubleshooter
Hes high
Continuity is a trickster and I'll tell you why. Some meters will only read to a certain value and above that they will give O.L. when you still have continuity. Surprised you left that out. I don't trust it of use it. Spec sheets often don't give the range of operation. You have to 'test' your meter to find it's values. Course that's part of knowing your equipment.
Joe, thanks for your input. On a manual ranging meter, continuity is also the lowest scale range of the meter. If the resistance of the load you are checking is higher than that scale, you will get OL. 200 ohms is common. Beepers will stop sounding around 40 ohms. Some meters may be less. Like you said, you never know what you're going to get. I like the "trickster" description. Very true.
Video notes :
1) Ohms measures resistance
2) continuity meant to see if a switch is “open” or “closed”
Examples:
Ohms -> compressor Motor
so, what is wrong with the circuit ???