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For students, it should have been mentioned that resistance to ground should have been tested while you were testing the other resistances. But otherwise, great job.
My compressor reading was 1.3 ohm 2.7 ohm and 3.4 ohm is that a good reading seems to be .6 to low shouldn't I add 1.3 and 2.7 which is 4 but I'm only getting 3.4 does it matter which red or black wire you touch which way ?
You really should be careful about messing with the terminals unless you remove the refrigerant. I have seen these blow out and hurt people bad. Most manufacturers state not to even remove the terminal cover if the system is pressurized. I once had terminals blow out when I restarted a compressor after a breaker trip. When I was new in the trade, I made the mistake of not megging out the windings before I restored the power, and evidently there was a ground fault at the terminals
I can not think of any way to blame a ground fault for a terminal blow-out. A fault almost instantly trips the circuit interrupter. And no-one removes the refrigerant from a system just to ohm out a compressor. That just doesn't happen.
2:59 Are you saying that the start wire _did_ burn up, or that you are going to check to make sure that it _won't_ burn up? Or are you asking, "Why did the start wire burn up?" It's a little hard to hear over the fan.
Acservicetech, hey man so what does it mean when these numbers do NOT add up? Lets say on this compressor you read 4 ohms between start and run, 1 ohm between run and common, and only 2.6 between start and common, totalling 3.6 Does that indicate that the windings are real weak or that they are real strong, and why? havent been able to find any good answers to this question, most people just say "If it doesnt add up, compressor is bad" - but is there any margin? and what actually causes the windings to read less/more ohms?
That tends to happen depending on how clean the terminals are and if there is a coating on the probe es where they touch. Try a different multimeter or pair of probes, or lightly sand the film off the probes and try again. If you are getting these readings and 0.L to ground on each, it is very likely it is just the meter probes, thanks
sorry I mean, what if your ohm readings ACTUALLY do not add up as they should? what does that indicate about the compressor motor windings? Ive done this "ohming out the compressor" test on several compressors, some of them add up perfect, others do not add up but rather are off by 0.2 or more ohms(either .2 ohms MORE than start to run, or .2 LESS than start to run. What does that indicate about the compressor windings? thanks, anticipating your answer, as ive said before - i havent found any thoughtful answers to this question yet..
@@josiahduehning5704 2 years later here, and i cant find a good answer to your question. none of the guides i've found explain why ohms not adding up means its bad, and what more or less ohms means, and how much margin is acceptable.... im starting to wonder if all these service technicians even know the answer
Hey AC Service Tech, thanks for the great channel. FYI this is a dangerous practice to do without pulling the charge. I just spoke with a manufacturing rep who has to go to court cases denying lawsuits because people get injured/maimed/killed from the peckerheads blowing out from incorrect servicing. Test from the wires, or power them off and pull the charge first.
@@acservicetechchannel Removing the cap to the peckerhead (wire terminals) without pulling the charge and powering off. It's the weakest park of the compressor, and under pressure. In the right circumstances pulling off a tough wire lead can cause it to break and blow out in the techs face, throwing shrapnel and maybe catch fire. The cap is there to prevent air from back flowing to prevent the air from coming into contact with the oil at a rapid speed and combusting.
Nice video thanks teaching! If the pin or terminal sticking out from the compressor is completely broken off meaning it leaves a lil hole, theres no repair for that? Plus the gas will leak put right? Asking cuz i had this situation and i told my super it has to be replaced but now u showed me the repair kit so i feel like told him wrong. The unit was empty tho no gas and breaker tripped
If there is no stub left or it is very rusted and not much there then you were 100% correct in telling him that it needs to be replaced. You can't fix the hole either where the refrigerant came out so it looks like you did a fantastic job in guiding him toward the correct decision, thanks
If you read 0.0 ohms of resistance between the start to run, run to common, or start to common with the power off and the wires disconnected then the windings are bad and are burnt together.
It may be your multimeter, usually you will get the accurate reading or 0.L which means the winding is opened up. Check your meter by itself to see if you are reading 0.0 when the probes touch and clean the compressor connections before taking readings, thanks!
Nice video ACSERVICETECH. Two questions. 1) is there a general specified number of ohms for the compressor windings or do you just need to check what that manufacture has. 2) are you checking the Amps for the compressor or the main line to the contactor. Thanks in advance I appreciate it.
He was checking the amps for the compressor. He also checked his pressures because an overcharge would cause your compressor to work harder causing it to over amp. More amps means more heat which is a cause for burnt wires.
Normally the manufacturer of the equipment does not provide resistance readings for a compressor. Normally all 5 ton (60,000BTU) units and less are right around the same ohms ratings as this one. They may range a little higher but are pretty close to these measurements. You may be able to look up ratings from a compressor manufacturer. The important thing to remember is that the two ohm ratings added together will match the start to run rating. If that is the case then the windings are good as long as you do not have a resistance reading from any of those terminals to the ground frame.In the video I did check the main power wire coming into the unit but IshockO is right, I was just checking the compressor amperage to see if it would go up or down. I knew I had a constant amp reading from the psc blower motor which would not change so I just took the whole amp reading of the unit. That would be different if you had a ecm or variable speed blower motor, then you would take the compressor amperage only. Great Questions! Thanks!
AWESOME!!!! Thank you you so much ACSERVICETECH! I really appreciate you taking the time to give me a good explanation. I'm sure I will have more in my new journey as a newbie LOL! Thanks again.
Thanks for sharing your knowledge. My friend unit compressor doesn't start, the common connector is broken and the numbers are 2.2 and 4.3. But the test of the s r gives 6. And should be 6.5 according your explanation so there in any percentage difference or needs to be the 6.5 ohm? Thanks in advance for your answer.
There shouldn't be any percentage difference but check the resistance reading with your probes touching each other first to make sure they are still reading 0.0 ohms. I just had a set go bad on me actually. I always check the accuracy of my meter first before reading ohms. Also sometimes the connection to the probe is not good so try different positions or pushing a little harder too, thanks!
check to make sure your meter reads 0.0 ohms of resistance prior to testing from lead to lead. Also check to ground to see if there is any resistance. There shouldn't be.
You turn the power off, expose a single hot wire and clamp around that. In this case, there are two hot wires so either one. The hot wire must be at the inlet of the unit, basically amps from the outdoor fan and compressor at the same time, thanks!
Why didn't you hose out that outdoor condensing unit coil, it looked filthy dirty on camera to me. I would have went there before even considering messing with the charge or amp test first. That's probably what blew the capacitor and burnt the compressor wires in the first place. Also I would have tested each terminal with continuity to chassis (cabinet ground) before committing to the compressor being ok. I just had another one this week that T2 on compressor #2 dead shorted to chassis ground on a 480V 3 phase scroll in a 10 Ton Trane Voyager package unit. Um yeah, I have been at this awhile (16+).......LICENSED as well...... John
I've been at it awhile as well. (35+ years) I'm confident he cleaned the condenser coil. He's not stupid. The purpose of the video was to show how to Ohm out a compressor, not do an entire service call.
hi i just did a nitrogen test for 45 min and no leaks then pulled vacum to 300 microns now where do i add freon liquid or suction line i have a piston thank you very much i watch all your videos itsa 410 freon
If there is refrigerant in the outdoor unit then you would open the service valves. If there is no refrigerant in the outdoor unit then you add liquid into the liquid line to break the vacuum, thanks
Imagine that compressor is from electrical aspect ok. I had a situation that compressor didn't want to work more than 6 seconds. Than just shuted down. Is that connected with lack of gas or possible with some other things? Its about heating geothermal pump. Company that solved the problem said its was about lack of gas and some dirty filters.
If you have a low pressure gas switch hooked to the vapor line and you were low on refrigerant then yes the sensor would open up the 24v circuit needed to close the contactor in order for the compressor to continue to work, thanks!
This video helps alot thanks. But the other day I was reading 0.9 ohms across all the three terminals on a mini split, what is my issue here if you know?
. Thanks for your great videos . How about the compressor showes the right ohm and even turn on but doesn’t make compression, low and high side both stay on same pressure. What could be wrong ?
That would be either the compressor valves or the internal pressure relief. That means the compressor would need to be changed out as they can't be fixed on a hermetic compressor at least, thanks
acservicetech I didn’t check the amp draw since the compressor never turn on for a long time just for 1 min and it stopped but the ohm check was good. I just found out , the pressure Raised too much , because the Condenser fan never came on . And today was 103 , hot summer here . it was a bad pressure control switch, the one control the fan , Thats why the compressor didn’t came on I guess Thanks again for your info it helps big time
