Testing if an HVACR Compressor is Shorted to Ground, Open, or Overload Tripped!

[@acservicetechchannel]

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[@paulpeter2869]

Hi Craig! Love your videos! AMANA furnace with a B1 code (module not communicating with blower motor) emerson aa25650l variable speed. Meter reading from R-W is 0.04V at the control board and the rest of Tstat wires are 27V. Do you know what could be the problem? Thanks very much!

[@paulpeter2869]

The motor is working fine as per ohms test at the 3 pin connector

[@dayjavu2586]

Do you have a video on low, medium and high temp compressor difference?

[@pehvac9198]

Thanks for all the amazing knowledge boss

[@abelmouzount8817]

Hi I just had A unit where we put all new wiring box / outlet then change the capacitor but end up with no running fan after ordering a motor fan condencer got it changed the fan started working but the house isn't sending a cool air in the house ?? So I'm afraid there's a problem with a bad compressor or just cuz of the hot weather that I need to hose it down with water then cool it off then try it works? I wish I could get some guidance from anyone here that faces similar problems? Thank you

[@newstart49]

Great video!! Suggestions and beyond ; 1. If the IOL is stuck open and it shouldn't be (Cold compressor etc), try hitting it with a 2x4 to unstick it temporarily until the repair/replacement can me made. Sometimes a sudden shock will get it to close. Sounds unprofessional, but if you get it going for the weekend, you're a hero! 2. After turning off the power to the outdoor unit, push the contactor fully in- to make sure the power is off and to bleed the capacitors at the same time so you don't get bit. Check as well with the meter to make sure power is off. 3. If nothing is running outside and it should be, don't be fooled. A bad duel capacitor can cause the compressor and the motor both to overheat and shut down. 4. Plastic forceps come in handy for quick connecting a temp wire or meter to another wire or capacitor for testing. 5. Always test a grounded compressor at the compressor itself, the wiring to the compressor may be shorted to ground (Made that mistake one cold day covered in snow- but only once) lol 6. A float drain switch in the main drain can flicker the low voltage on and off quickly causing chatter at the outdoor contactor and also cause the scroll compressor to run backwards resulting in a no cooling situation and a noisy compressor complaint. Install a time delay relay in the circuit and set it for one minute minimum. 7. Always verify your meter is working by testing it on live voltage first! Assuming the power is off because you don't read voltage just might mean your meter just quit working. I've enjoyed HVAC work for over 48 years and I still love it!

[@j.bennett2485]

Hands down the best teacher and KZbin channel on here. For someone who likes troubleshooting and fixing their own equipment these videos are incredible.

[@soheil7673]

This tutorial very useful. But that's part of compressor checking. That's electrical checking only. What if the compressor is seized. Or weak. One of the best solutions checking mechanical functionality would. Be pump down the unit to see if it pumps down correctly or not. On the other hand all inverter units have same winding resistance as the inverter controls the load of compressor by increasing and decreasing the Amp and volt rather than winding. Big like to all your efforts during last couple of years. Appreciable

[@NoWayCraig]

If you get OL between any terminals, common to run, run to start, start to common, you’ll get OL on your meter. That’s means the winding is open. It’s possible to just have one of the 3 open, 2 of 3 open or all 3 open. If the compressor is severely overheated the windings will be open until the internal overload resets. You can cool the compressor off with cold water or ice. A lot of times you’ll hear the internal overload reset, it’s a mechanical “click” noise. If you check any terminal to ground (any terminal to copper ref line works best) you’ll get continuity or a “beep.” If you get a beep on any that compressor is dead. On a 3 phase compressor all resistance (ohms) from terminal to terminal are EQUAL. On a single phase compressor common to run and common to start=start to run….run to start is the LARGEST RESISTANCE VALUE, common to run is the LOWEST RESISTANCE VALUE.

[@huskyng6981]

Hi Craig my situation is same like you mentioned Compressor, , Start - to run 2.9k ohm, and common - to start =OL, and common - to run = OL OPEN, And I haven't turn on ac for days even crazy hot weather too, is there anyway I can fix it??? And I also check , common - to ground green =OL, Run - to ground 39k ohm + and meter ohm keep on increasing, and Start - to ground 39k ohm+ meter keep increasing???is there way to fix or I have to replace a 5 months brandnew compressor?? Thank you for your help and your time

[@EarthaNell]

The contact is pulled in, but the compressor nor fan start. Got readings for compressor wires and terminals, but one wire from condenser fan had no reading. Will dead fan motor prohibit compressor from starting? 1996 Goodman 3 phase condenser unit.

[@harpoon_bakery162]

Thanks for keeping parts that went bad. That helps tremendously to lock on a visual.

[@MiguelRamirez-ld7sy]

I've been messing with a Honda generator and it's gen Head. I kinda, sorta see some similarities between the two. Then again the extent of my voltage meter experience is the continuity setting on my volt meter. Great channel by the way.

[@abnergarcia6252]

Great vídeo! I would love to see a video where you troubleshoot a compressor with bad or weak valves.

[@joseorta9928]

Great explanation...Im a minisplit tech in Apodaca Mexico...in yr videos I learn alot...

[@rolandotillit2867]

When the shaft seal is puking out oil and refrigerant, the compressor sounds like a bunch of marbles when you try to run it, and there's metal paste in the discharge line, I assumed it meant the compressor was shot, good thing this video exists to make me reconsider.

[@muneycorn6310]

Love your videos Mr Craig ...You and Mr Brian (kalos) are great teachers.Invaluable to those of us learning online.

[@apprenticephil649]

Love the video but perhaps showing how a compressor analyzer or start kit can help diagnose a bad compressor would be informative as well.

[@sewerat11]

What ohm setting do you recommend

[@josepalacios627]

Im working on a unit rn with compressor windings that are good but it doesn't start. I tried that grounding test and that's what it was. Im so grateful you made this video lol

[@monteglover4133]

Not all failures are burnouts. There are 3 types of Compressor failures opens, shorts and burn outs. A standard VOM may not find a high impedance short to ground a merger maybe required. I’m a HVAC&R service tech with 40+ years of experience.

[@monteglover4133]

Generally shorts to ground are not a burnouts or have significant amounts of acid in the system. A burnout will generate acid from insignificant to severe and often create sludge if any doubt use an acid test kit. At a minimum a high capacity liquid line dryer should be installed when changing a compressor and the refrigerant should always be changed.

[@eliogonzalez3038]

Thank you so much for your help 🙏 and it help me a lot God bless you

[@miguelurbina3004]

Yes definitely a megohmmeter is the right tool for this a vom is not capable of reading such values

[@TheWpruden]

Every hvac tech should have a megommeter to test for those high impedance shorts!!!

[@monteglover4133]

@@TheWpruden even the cheap ones, will work if it has a high voltage test mode

[@JuanGarcia-qu8ms]

Thank you for your help, I have learned a lot with your videos, I have already started my own business, I really appreciate you help. Thank you.

[@nihalahmadpasha7607]

Good for every technician thanks

[@acservicetechchannel]

So nice of you

[@carolineandjaimegonzalez9839]

Smelling the refrigerant works too. Spraying just a little of bit of refrigerant in your hand and if its smell like burnout tells you that you have a burnout compressor as well. That's just another easy way to identify a burnout compressor.

[@acrservicesmathewr7565]

The oil will also be black. Or darkened. It does have a terrible smell when it burns out or I have seen a ton of foam which indicates liquid migrating to the compressor oil and sludging it

[@rodgraff1782]

Also the wonderful smell of phosgene gas.

[@tutata7228]

Excellent video, I'm not working on ac at the moment, but I still want to keep learning more and refreshing my memory 😊👍🏼

[@acservicetechchannel]

You can do it!

[@tutata7228]

Thanks! 😊

[@ricardomunoz9617]

Thank you, sir. Your videos are very helpful They help me refresh my mind all the time.

[@TheWpruden]

A megommeter should always be used to test integrity of winding insulation. Not a multimeter.

[@rodgraff1782]

Finally someone who knows how and when to use a megger. I have three AMEC megohmmeters, crank style. It is the proper tool for checking the condition of the insulation on the windings to ground. If a system has moisture or contaminants in the oil, it will fail a megger test.

[@mrman5374]

This guy is simply THE BEST!

[@acservicetechchannel]

Thank you for your support!

[@mrman5374]

@@acservicetechchannel No really thank you for what you do! We live in a time where training is so poor, but you have helped me tremendously!

[@davidstofanak3222]

We just had our compressor fail after 2 years of service. Its a mr cool universal heat pump DIY install. We had an authorized MR Cool tech come out and diagnose it and covered its replacement but I'm worried maybe we wrong during the install. The Tech was super impressed with our work and said everything looks great but I'm worried. The compressor sits on ground level outside the house and the AHU is in the basement maybe 4-5' drop in grade. When we installed the line set we didn't install any oil return bends just kept it as straight as possible hanging them basement ceiling. Having a hard time researching oil return bends not a lot of quality information on it. I'm just worried if we replace the outside unit we would potentially be in the same spot in 2 years if we install it the same way. BTW your videos are awesome!!

[@jesusadrianbarraza3061]

The best chanel for hvac hands down!!!

[@acservicetechchannel]

Thank you for your support!!!!

[@fernandocortes9420]

Hi I love your videos thanks for keeping us learning God bless you Sr 🙏🏼

[@acservicetechchannel]

Thanks for watching!

[@albertrubian2971]

@@acservicetechchannel Good day Sir First of all sorry to how can i speak English but i hope you understand... What are the possible problems to compress Air dryer with alarm overload and everytime i turn on the breaker it always tripping (3 phase)

[@emmaa427]

Thx for sharing your knowledge!

[@mikemorton6219]

If you get acid smell from refrigerant, it's a bad burnout. Put ammeter around all 3 compressor wires. If meter moves at startup, compressor is grounded.

[@douglieberman6406]

That means we are looking a variations in current related to different resistance, or the resistance and current are inversely proportional. As the resistance goes down the current goes up !

[@LloydAveryM]

This video was very thorough.

[@blh3741]

your videos and books are great! thanks, Brian

[@scetchport]

Easy to follow info. Thanks. In process of testing those in dometic harrier inverter rv airconditioner.

[@Reefertech]

So basically if the compressor is off on overload it would read OL between windings? And if it’s shorted to ground you would get continuity(tone) from the shorted winding to ground ?

[@specialK_hvac]

If you measure ohms between run and start but not common and run and common and start that's am internal overload that is opened

[@officerkrupke4966]

You would read continuity to ground on all windings since they are all connected

[@2169scs]

Very good education on AC compressors , thanks

[@clifordmichel8981]

Great video, Haiti represent

[@handyertanto76]

Thanks you sir, for delivering this information. It's usefull indeed and comprehensive. Greetings from Indonesia. 🙂👍

[@jimbola77]

awesome! Craig thank you for sharing! all your videos are so well explained! have a nice and safe weekend.

[@acservicetechchannel]

Thank you for watching!!

[@copkhan007]

While the system was running, my guages were reading equal pressures on both high and low sides. I checked the capacitor, and it was good. Disconnected all three wires to the compressor, I was reading 1.3 ohms between the 2 terminals and OL between the other 2 terminals. My guess compressor is bad.

[@tshokaphiri8381]

Hi guys, im a service technician in Botswana and love the great work y'all are doing with the videos! Coincidentally i had a similar problem just the other day with a Maclaren 12000 btu packaged unit! The compressor was heating up and much like in the video the thermal overload kept it from starting! I did an ohm test, continuity test and ground test to the compressor and everything checked out! I also tested the capacitor and also did a visual test and still everything seemed legit! I then took the decision to remove the thermal overload to see whether the compressor would start (big mistake) long story short the compressor overheated and shutdown! Can you help on what could have been the problem and what could i have done different

[@ApartmentMaintenance]

Great video & explanation Craig 👍

[@acservicetechchannel]

Glad you enjoyed it

[@tytig94]

I have that same meter! I love the dual temp probe feature, and LRA/inrush option. Also the min/max option is cool. Great video, thanks.

[@tytig94]

Also your vacuum videos really saves me a lot of time. I use your 3 core tool removal tool method with 2 hoses, I pull a vacuum in 5 minutes or less with valves open! My company wants me to train everyone on how to do it, I did give you credit. I wish more guys would spend time mastering their trade away from work.

[@noeeon9910]

You guys make me want to learn the trade!

[@Boojyman]

A good meter will tickle your peter

[@daveyt4802]

I have a Copeland that is 23 years old. Just have R22 with 30psi on the low side. I charged it up to 60 psi a few weeks ago. My current problem. No leaks found yet...

[@phongpham1453]

thank for sharing your knowledge.

[@acservicetechchannel]

My pleasure!

[@bineshchauhan8713]

Wish you long live and better doing Happy teacher day 💐

[@roymarksberry4152]

If you get completely on your meter from one of the terms on the compressor

[@andyclark7927]

Well explained I would tell any tech to have a look, good job

[@douglieberman6406]

I would like to try white neutral line to neutral bar in breaker box for common of compressor, as start to common L1 Run to common L2 And common a neutral line to breaker box neutral. 2 breaker switches for compressor, one for L1 and other for L2 . It just that neutral (white ) is common and also hook up the ground line! Same goes for the 240 volt e c m . ! Just like a 240 v a c light bulb with 2 switches and one neutral.

[@wtfman5313]

Just for info, I was taught that OL on a DVOM / multi meter is “Open Loop” because an electrical circuit is essentially a loop.

[@thembones12]

OL = Open Line = Open = No Continuity = broken connections = broken loop = broken wire = OFF line = broken circuit = it's not connected, it's open....

[@wtfman5313]

Dt Candia - yeah, open loop.

[@jcmendoza8285]

you guys are a great source of Knowledge Thank you!

[@acservicetechchannel]

Thanks for watching!

[@hermesyanez1431]

very nice buddy how always!, i love it all your videos, i follew you from Honduras, regans master!

[@MrRalph438]

Have your book and quick cards, Posters are also helpful. Recommend them to everyone in HVAC Trade.

[@acservicetechchannel]

Thanks a lot Ralph!

[@spartan5106]

Excellent video, thank you for sharing

[@guyinpajamapants6892]

Always check at the taps!!!

[@michealmanuel2143]

Very very good information sir Thank U very much 👍

[@acservicetechchannel]

Thank you for watching!!

[@francisguchie1973]

So detailed - I like

[@Thomas-eh8lb]

Why cany you clean the coil if you can clean the lines? Thanks

[@Hummer999xx]

During startup the condenser makes a loud thumping noise, does it mean the compressor is bad? It’s a new build. The technician came out twice and said the compressor is not bad. I don’t believe it. My neighbor isn’t having the same issue.

[@jaykesapalaran5434]

Wow thank you very much for sharing your knowledge ❤️🇬🇱

[@SarahJoRDR2]

I'm a 63 year old female and yes we still get Cheated. A service guy checked my wire outside said compressor was leaking in my house but never went inside, anyway wanted, $2,600 to fix it. I have no son or husband so any small info the better for me. Thank you

[@zekenzy6486]

Great Video. Have a nice weekend and Holiday. Thank you for sharing ^_^

[@acservicetechchannel]

Thank you for watching!

[@baz159]

Nice 👍 video, can you make videos on 3 phase compressor phase reversal rotation

[@hectormedina9009]

Continually blowing

[@turbolag98]

Is it a failed compressor if the compressor is pulling double LRA even after installing a hard start kit but the windings have continuity? Compressor isn’t tripping the circuit breaker either

[@specialK_hvac]

Yes that would be a failed compressor if it is mechanically locked up like that. Sometimes you can give it a bump and it will free up but that's a stop gap solution

[@Hvacnc]

Thanks for your videos man!

[@acservicetechchannel]

Glad you like them!

[@veriitas33]

apparently i have a hydronic ac unit and two HVAC guys didn't even want to fix it. they didn't even want to check nor even try to diagnose it. the fan run outside and so my unit fan inside the house and the only think it does is cool and then suddenly warm air through out the day and I would feel cool few times but never how it used to. so two hvac guys did not even bother trying to even check it.

[@armandogeronimo8141]

Good day sir amassing tectnic

[@jgv1]

My compressor was condemned by an AC Service company. I checked it and it's fine. Good resistance values! And OL to ground. Scum bag AC company.

[@hvacrtroubleshootingsimula301]

When it comes to identifying the compressor winding, I usually teach the winding opposite the highest resistance is the common winding. The second highest resistance is start and the lowest resistance is run winding. The major question is, why is the start resistance greater that the run resistance?

[@andreagate542]

There is no comment on my name only a run whining and start whining and they both meet at a common point which is the common connection or C terminal

[@brandonnewyork11]

Because the motor has an in-rush of current when it starts which needs more resistance (start Winding has more resistance than the Run Winding

[@igorshapovalov8527]

Thank you, very helpful

[@daveyt4802]

Megger work also? OL usually means 10 mega ohms or more. Meggers go much higher...

[@barbarafogle3541]

In the description for the video they forgot to mention a short Turn to Turn. Learn to ask can she run. C+S=R

[@Saulgr]

How do you know when the compressor all 3 has to be the same value and when the 2 has to match the 3 value C-S= 3 C-R= 3 S-R= 3 Thanks AND C-S= 3 C-R= 2 S-R= 5

[@mtbbiker6401]

Are there better connectors for compressor wires than using wire nuts?

[@AdamHuishStreaming]

helpful and great video. thank you so much

[@Gabriel-vz7ml]

Thank you!

[@wasimedoo1506]

Some time the compresses read good but when it starts to run then you know it will run and stall

[@seek3n]

So when ohm is high=burnt winding? And if there's resistance from compressor to ground showing resistance =shorted to ground? Because that means is connected

[@Tito-hvac8]

Great video. Thanks💯

[@vsjapan]

Great video. What is it that is causing the ac breaker trip frequently? Checked all the electrical of the condenser unit and all seems to be good. The capacitor is new the fan motor has no issues the contactor looks good. Could it be the compressor causing it? If so how to diagnose and fix? Thanks.

[@thembones12]

Check the circuit breaker itself...Make sure that ac breaker it not warming up or hot when you start/running the compressor, check the temp of the circuit breaker-using HVAC infrared thermometer...Also, With your HVAC clamp on ammeter, check the Starting Load Current SLA and Running Load Current RLA...

[@vsjapan]

@@thembones12 Thanks for the reply. Just for your information, it was the compressor. It was overloaded with Freon. Overcharged with the Freon. Recovery of the freon did the trick. The breaker has not tripped since then. Thanks.

[@kurtsmith5202]

Ours want to start up , but won’t you can hear it engage but , will not start up , is our condenser gone or is the capacitor

[@rogerf3622]

Great informative video.

[@acservicetechchannel]

Glad you enjoyed it!

[@techdan7098]

My technician came today and put the clamp on the black wire while the system was running. He said the compressor was bad based on that reading alone. What should be the voltage when connecting a compressor to the black common line while running? Can you really tell if a compressor is bad by just clamping the black wire?

[@goldhammer561]

Awesome video

[@acservicetechchannel]

Thanks for the visit

[@steelod1528]

Hey craig could you do vids on light commercial equipment not too many vids on that

[@brianb5779]

Damn excellent video and information so thank you..

[@jackmcdonald7391]

I read ohms to ground between a compressor winding and the copper line to it and when I plugged it in it ran just fine.It was a scroll compressor.Not sure how it was possible but I almost condemned it for no reason

[@romarro4616]

Awesome tutorial

[@acservicetechchannel]

Thank you for watching!!

[@techfive7202]

I had a carrier 2 stage residential compressor that threw me off. All terminals with plug removed showed continuity to ground but the terminals ohm out at .6 .8. .2. Not exact numbers but close. Normally the ohms are higher plus I never seen them add up when it is grounded. The compressor had 2 plugs which I never seen before. The other plug had only 2 terminals that I did not test. It was 2 stage obvious. Would trip breaker as soon as the unit turned on. Unplugged compressor and the fan would run. Another odd thing is it would trip as soon as I put the disconnect in without the contactor engaged

[@pharoahmonk50]

Great info.

[@rodgraff1782]

You’re missing one of the possible diagnosis. It is called a turn to turn short . If the resistance readings don’t add up like in your example,something is wrong with the windings themselves. Insulation has broken down and the windings can be shorted to each other, or a individual winding can have a turn to. Turn short. Compressor windings should also be tested to ground with a megger, which is a high voltage insulation tester. It will find ground faults that your 9 volt ohmmeter can’t find.

[@shaneisaac1184]

Hello Craig, which of your books would be best to learn the fundamentals of hvac split and troubleshooting methods? Am trying to save costs by DIY as much as I possibly can. Thanks.

[@delroymorrison7599]

If the COMPRESSOR show normal no reading is it good or further testing is needed

[@andycamm6317]

I wish people would actually test a compressor correctly before condemning them

[@Gameboy_Steve]

Awesome thanks again

[@frankduarte7109]

Great video!

[@ajenjohnson7413]

I do enjoy your videos, great job there, but I do I have a question. I have a heatpump ( portable ac) and it is kinda noicy and I did some research on that and I learnt about using something called ac compressor blanket which wraps the compressor completely to insolate the noise it produces, can I use that on my portable ac compressor? If yes can I make a homemade cushion ac blanket and use that instead? What is your advice, please let me know. Thanks👍

[@jeremymorgan7199]

I had a compressor blowing the breaker. I check resistance from C to R and got OL, C to Start was 47, start to R was also 47. But it wasn't grounded. The compressor wouldn't start tho. So I changed it. Did I do the right thing or did I miss diagnose something?

[@StanleyMarcelin]

I thought they say if a compressor fail you need to replace the whole furnace and condenser unit??🤔

[@simpliciocamirino2271]

thank you for that sharing

[@thesetruths1404]

Great video...thanks. This is what I have, does it indicate a bad relay? Whirlpool WRT111SFDW03. 7 years old. 11.2 cu ft size. Freezer on top. Start relay P/N: WPW10448874, aka W10448874. Capacitor ("cap") P/N: WPW10662129 Test relay connections with capacitor on the relay. Results: when together I can get cap to charge and discharge thru the start relay, just like it does when it's off the relay. With cap off and on, neither of the lower holes have continuity with each other. The hole on lower left has 0.0 ohms resistance thru the bottom blade of the back of the plug. The lower right hole has no continuity with anything but can be used to charge the capacitor for testing. The upper hole has 0.1 ohm resistance to the top blade on the opposite side. Remove relay cover and visually check. I cannot get combination relay apart without breaking it, so I haven't committed to that, yet. Ohm test the fridge compressor pins again. Make sure the Common (top) and lower pins are within 3 ohms. And the two pins at bottom should read about the sum of the Common with the Start and Run pins. See KZbin video... Results: Top and Lower Right : 4.4 ohm. Top to Lower Left: 6.0 ohm. Two bottom pins: 10.4 ohm. None of the pins are shorted to ground. My problem is it suddenly stopped cooling without noises or warning, but I caught it from hearing loud buzzing noise from compressor and relay area, and compressor was very hot. No smoke or smells though, and wires did not seem to be hot. Do you think it's the combination relay? Many thankz!

[@sonamtobgay1797]

Plz can u explain me why my cold store getting off time and again..I had change contactor also

[@egwuchehumphrey5608]

I'm sorry sir if u change d plorg of d compressor it will work again ba