HVAC Compressor Checks - Short to Ground

[@Woozy-pt9js]

Awesome had to have a quick refresher just to make sure my diagnostic was correct. Thanks for the video!

[@johnjennings-JJ]

Not much too it but to do it! Thanks to you sir. Been a minute since I have seen an 0311.

[@Woozy-pt9js]

@@johnjennings-JJ I know a few 0311s working the hvac trade. Not sure why this job field attracts us. Maybe it's the long work days with little sleep mixed in with low crawling and uncomfortable spaces 🤣.

[@simmonsjr25]

Another awesome video. Keep them coming.

[@johnjennings-JJ]

I hope you remember how to do this!

[@simmonsjr25]

@@johnjennings-JJ yes indeed I remember.

[@johnjennings-JJ]

Too easy.

[@Pubstomper23]

I needed that . To understand how to ohm out a comprossor

[@soloch69]

Great video like always my friend keep them coming 🙌🏻🙌🏻🙌🏻🙌🏻

[@johnjennings-JJ]

Thanks SOLO TECH.

[@Rhenexful]

Very detail... thank you for sharing

[@johnjennings-JJ]

Thanks.

[@josephspitzley9009]

I had one the other day that was shorted to ground on me. And another tech came out and swapped the capacitor and it worked fine.

[@johnjennings-JJ]

And you checked it at the actual terminals on the compressor? Or from the contactor?

[@josephspitzley9009]

@@johnjennings-JJ I did all three terminals and all three wires. Got a reading on all 6 never a OL.

[@johnnygallardo76]

You didn't specify if it was bad or good when checking it for resistance what number should it display if it's good or bad and in what way?

Scroll compressors will have 20 olms to ground but the motor is fine. The windings actually sit in the refrigerant to be cooled.

[@johnjennings-JJ]

Thanks for leaving a comment. There is a lot of info out there such as that. I hope that techs would search out the specs on all the motors they come across in the field before assuming it is bad.

[@joehead1294]

@@johnjennings-JJ AE4-1294 Emerson/Copeland bulletin says not to meg a scroll but if you do the min is 500,000 ohm winding to ground. 😵‍💫

[@johnjennings-JJ]

I hadn't seen that bulletin. I will check it out. Thanks for sharing.

[@JuanSanchez-nn1db]

Adding the Run and Start should equal the C reading right?

[@johnjennings-JJ]

The common is just the terminal labeled on a PSC compressor motor. The testing of run to start gives you the added resistance of both windings. Run winding is from R to C, start winding is from S to C. There is no common winding. It is "Common" because that is where the run and start winding both meet "the other side of power".

[@Rod264]

I have ohm out my compressor and my number where high will that indicate I have a bad compressor?my number don't match from R to S.

[@johnjennings-JJ]

The numbers might not match exactly but should be fairly close but higher resistance values could be indicating a problem with the compressor motor. But I honestly don't get wrapped up too much because I don't know what the values should be exactly until I look the up from the manufacturer. Then you can see exactly what they have designed and if your numbers are truly higher.

[@kastenusa]

My compressor pulls 110 amp at the start, LRA states 118amps. 5 ton unit. How much life left on my compressor? Thank you!

[@johnjennings-JJ]

Tough one. Sounds like it is within specs! But I have had them go bad while I was at the unit too. Let it run until it doesn't is what I would say. If you want a good read, google this - Trane Snowball or Snowball 2. compressor.

[@kastenusa]

@@johnjennings-JJ I will. Thank you!

[@simmonsjr25]

Thank you. You have let the secret out of the bag. Thanks for sharing 👍

[@johnjennings-JJ]

You bet! We got a lot more stuff to cover though.

[@rickdeckard1075]

shorts can be intermittent though, depending on applied current/voltage or vibration...

[@johnjennings-JJ]

You are right sir, and I especially hate intermittent low voltage shorts.

[@jollyscaria1922]

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[@rafaelandreano]

What happens if the resistance values are extremely high, I’m assuming is a bad compressor but what could cause to have such a high resistance ?

[@johnjennings-JJ]

Well...too much resistance for "X" amount of voltage in general will not allow the thing to run. But I (personally) have never had a compressor with an extremely high winding resistance. Not saying it can't happen but I just haven't seen it. Best practice is to get the manufacturers specs I guess and compare it to the actual readings. Example I have seen is a tech put a 480v rated relay coil in a 24v system...just didn't pay attention to the relay they grabbed...and nothing worked. They check voltage to the coil and it is there, just the relay isn't working. They had a relay with more resistance than the voltage could overcome and energize the coil.

[@mdtabul4043]

Nice

[@johnjennings-JJ]

Thanks

[@lynnprince6635]

Wow, really you left out the reson for the video. 1.7 and 1.4 should equal close to the 2.9.😮

[@johnjennings-JJ]

That it should... but I have really never seen them add up perfectly. The whole resistance checks and ohms law works good with DC circuits and purely resistive circuits though.