Bryan Orr gives a quick lesson in Diagnosing Open & Short Circuits. Read all the tech tips, take the quizzes and find our handy calculators at www.hvacrschool.com/
I've been in the high-tech industry for over 20 years and this is one of the best videos on basic electrical troubleshooting I've seen in my life. Well done and congrats!
For a dum dum like me I want to thank you for repeating the important parts a few times. You kinda talk a little too fast for me so I'd have to rewind several times but this time I didn't have to do that. Thank you!
I think the confusion comes from the word "open". In normal parlance what we usually mean is that traffic can flow, if a store or a venue is open it means you can go in and out as opposed to when it is closed when you cannot. Open means GO whereas closed means STOP, which is the precise opposite of what we mean when we discuss electrical circuits. If a circuit is open it means electrons CANNOT flow. Some beginners may benefit from thinking about a switch when discussing open circuits, if you imagine a switch being open it makes a little more sense as to why electrons cannot flow.
I would have liked to see you connect the multimeter at the terminals of the timer to show how to read the short or open. Just for folk with poor electrical knowledge.
Thanks for video, but I would have a question to you. When I was checking pins of EGR to see if there is positive and negative in each pins, but I saw that there were both Positive and Negative sides on the Same Pin. I didn't understand that if it was a short circuit or How?
I was looking for a grounded harness on traulsen reach in couldn’t find it. I’d ground out moved the wire n lose it. It kept tripping breaker but not immediately usually after an hour or so then boom it’s trip
I got a drop down light fixture emitting an ozone smell even with no bulb in. With the bulb in it flickers. The switch panel on the wall crackles when turning on and off, but it's actually the switch right next to the one that controls the light with the ozone smell that does that. The breaker is not tripped. Do I have a short circuit in the switch panel?
So I had an interesting problem happen recently. I installed a new AC unit in my car and not even a day later, the circuit board in the AC unit had a hole burnt into it. I checked my AC fuses and relay and neither of them were blown. Does that mean that a problem occurred before the fuse box and relay box closest to the battery? The AC was also off when it happened.
At around the 5:00 minute mark, you say there should be no connection between the isolated wires and ground, so would you set the DMM on continuity or resistance mode? And then what? Place the black probe on the case [a metal surface] of whatever it is you are working on, and the red probe on one wire, at a time - if the DMM beeps [on continuity mode] that is bad and if the resistance is low [on resistance mode] that would also be bad, as it indicate a short to ground? Did I get that right? Sorry, if this question is all over the place. I’m just a hobbyist and work mostly on pcb circuits, small stuff. Please reply. Thank you
Teacher with full respect I downloaded the hvac school app is very cool and with alot info but the tips and tech part when I select any part of it it crash and stop working I sended report why is acting wired but only in the > tech tips I hope u fix that part it has alot of important content which I was asking me self
at 3:23 and 5:12 why does he put a marette on all the wires then take it off? what is the purpose of that. At 4:05 how would you tell if there is a short? would you get a measurable resistance with it disconnected at both ends? I am an hvac student and have used an ohmmeter before.
That’s why he says to do it this way because of the distance many times you can’t run ohms meter to both sides of a wire, so by disconnecting the wires on both ends, and wire nut them all together on one end, you test wires on the other end. So you then place ohms meter leads wire to wire and since they are all connected on the other end, they should all give the same reading testing 1 wire at a time to each of the other wires, when testing for an open circuit or broken wire in the casing. If testing for a short circuit in the casing where 2 wires are broken & arcing together you would disconnect all wires and keep them separated on both ends, and test one wire at time line to line you should have the opposite result with zero ohms. Hope that make sense, when wire nut together the other end should all have roughly the same ohms on any 2 line to line, & when separated on other end there should be no ohms on any 2 line to line. Hopefully I answered your question.
@John Sutter If you wire nut at the furnace you test line to line at the thermostat. If you wire nut at the thermostat you test line to line at the furnace, but disconnect all wires on both ends before placing wire nut. Hopefully this straight to the point answer is clear compared to my long explanation, and directly answers your question.
I'm kinda confused on the diagrams. If you have say 4 resistors and the side of the fourth that's directly before the third is 0V, then which one is shorter? The third or fourth? So like the first point on the third has voltage but the other end that current is passing through suddenly has zero. Is the a short on the third or the fourth resistor?
Without knowing what you're checking you could have a bad connection if it's meant to be grounded, or it could be that it's going through a load, or that the wires have rubbed together and have corroded. I'd double check that you are checking the correct wires as well.
SO much incoming information....now picture it: an old farm house from the 60's, trying to figure out with certain sockets have no power or why certain light fixtures are not making our bulbs shine... so maddening not knowing the different DB boards.
Obviously you aren’t a mechanic but would a short in a wire cause something to work when it’s off? My car is trying to start on its own and everyone is telling me a short in a wire to the starter…
