Yeah this channel is great for a newbie, like me. Dick wirz commercial refrigeration for techs book is HUGE too.

@@Nba19980what edition of the book do you have?

Good job man, Time delaye is a great find ! I wish the best for ya!! I hope you like racks. I have always found it very interesting. :)

Thanks man happy to help !!

How ya doing pooootz?

Thank you I'm glad to know It's a universal thing !

I've never worked on that but if I ever come across it I'll make a note of it !

I can try and get to it :)

That's an excellent comment thank you ! That's a wonderful way to do it. I have never heard of that most guys just look at it. ! Thank you for taking the time to share :)

So there's a timer on it so, It locks out the oil after a certain period of time so yes if I left it longer it would eventually lock out the oil but it has to meet a time limit. I hope that was helpful:-)

Yes, It is absolutely a concern. But if the pressure doesn't rise above suction , which in this case did not. It's kind of like it's on its last legs Maybe it needs to be rebelled or replaced. But if you see the pressure increase above suction rapidly then yes, that compressor's done, shut it down.It will cause issues. I've seen it where the compressor will Blow by And it will be at a 180 ps.I within ten seconds. That compressor would not feed oil and would more than likely cause a trip to breaker when it started. And If it tries to start with a bunch of liquid in it it could rip itself apart causing leaks and all kinds of stuff.

@@gendronhvac-r1269 thanks for clarifying, totally makes sense.

You would have saw discharge pressure. So for example suction pressure let's say it's 20PSI. If discharge was back feeding I would probably see around a 180psi. Or you might see it's slowly rise if it's not back feeding a lot. So it might slowly rise from twenty to a hundred. Hope that's helpful!

1) Before checking it for electrical issues I unisolated the compressor. I do this in case it turns out that something is faulty like the breaker or contacter and somehow power is fed to the compressor and it is turned on. If the compressor was isolated in this scenario it would more than likely destroy the compressor. Buy unisolating it before I troubleshoot the electrical I eliminate the possibility of possibly exploding the compressor if I accidentally turn it on it's more of a safety precaution. 2) if you try to start a compressor that is filled with oil the compressor will try to compress a liquid which is impossible to do causing damage to the compressor. by removing all the oil when you get to the stage where you will turn on the compressor the compressor will not be damaged by being overfilled with oil. You only need to remove the oil if the compressor is over filled with oil if it looks like it is properly filled you do not need to remove the oil. Also if you're a compressor is overfilled with oil it is stealing oil from the other compressors on the rack so you would need to push out all this oil to feed your other compressors. I hope that helps:)

The only theory that I can come up with is you are lowering the boiling point of the refrigerant. At 29 PSI the refrigerant boils at -4 and at 21 PSI the refrigerant boils at a -14. This difference will create a more dramatic temperature difference between the case temperature and the refrigerant which in theory could allow more to boil off especially if the TXV is stuck and we'll feed the same amount of refrigerant regardless. I would look up the factory specifications of the case which is more than likely negative -20 evaporator or - 15 evaporator. Then I would set the epr appropriately and then I would check superheat. Anyway I hope that helps

@@gendronhvac-r1269 thx! Yeah ur onto something with ur theory. They wanted the cases to run 100% of the time and adjusted the epr s until the cases were constantly running. A month later i come back to the situation. Thx a lot! I am a newbie but hadn’t thought of it at that level. Odd thing was that the cases were running perfect. (Odd to me i geuss) making temp. I was thinking the extra pressure exerted on the txv was affecting it.

Thank you for sharing that's wonderful input :)

You're right I didn't really find the root of this issue, I really wanted to produce the video. And this was a great example to do it But I did not really get to the route cause my first pass. It actually seemed like the redvalves were extremely slowly letting refrigerant bleed into it. I did a test for this but I didn't wait long enough to notice. It extremely slowly allows liquid refrigerant to come in Then when the compressor turns on the breaker trips. Hope that helps !

@@gendronhvac-r1269 good to know. My issue is very similar. Compressor turns on and runs for about an hour, then trips the breaker. Pressures check out, it ohms good, not grounded, amps are well below max, has oil, no obvious signs of shorting wires, contactor, breaker, and time delay have been replaced and I have tested/checked the internal overload. I don’t get it, runs fine, then will trip it. Only thing I can think of is there is a “feeler” wire in the windings that randomly touches and grounds out the compressor for a moment 🤷‍♂️

Could be a breaker on the way out. Check it with a thermal camera for hot terminals​@@Frostbyte911

I am not sure. I have a theory that it might be some kind of flood back. But we haven't found anything yet. It's working just fine now. unfortunately there's so much work that it's just kind of like we got to fix what we can and not spend like a couple days on an issue that seems to be working just fine at the moment. If anything comes with it I'll let you know. I also have another sub theory that maybe a very small amount of discharge is coming in through the valve plates. And this discharged is condensing down into a liquid causing it to trip. But like I said I need to kind of wait for a season in time where I can dig into the issue further. :) I hope that helps some

@@gendronhvac-r1269 I remember back in the late 1990's there was a 15 hp Copeland Discus unit medium temp system I had installed. Single unit split system. It didn't trip the breaker, because the breaker was 100 amps, it was an electric defrost setup, and with 25 kilowatts of defrost heaters, the electrician said the breaker had to sized for the combined load even though the defrost heater contactor power was interrupted by an auxiliary contact on the compressor contactor so during pump down the heaters would be momentarily cutoff. Anyway what was happening during the weekends during cold weather, or during times of plant shutdown, it was tripping the oil pressure safety. I was very puzzled by this, but I found out what was happening was, there was a small leak on one side of the cylinder head, and during very cold weather, the refrigerant was condensing into a liquid in the discharge line to the condensor (condensing unit on a roof, not in a warm rack room). I found this one day by climbing up on the roof, and seeing one side of the cylinder head frosted over, and the discharge service valve too. So that was leaking a tiny spray of liquid refrigerant thru the valve plate into the compressor body, and the cooling effect was greater than the crankcase heater, and the crankcase would fill up with a very diluted solution of oil+liquid. Then when the suction pressure finally rose enough, and it tried to pump down, all that diluted oil would trip the oil safety. Maybe something like that is happening with that one, and liquid refrigerant is slowly leaking into one cylinder, and then when it tries to start, it hydrolocks and trips the breaker because it can't compress a liquid. I don't think this is very likely in your case though, because that rack room is got to be pretty warm, that's a lot of horsepower in one room you have there!! The valves on your unit don't look like they're holding pressure very well, I remember on that Discus unit, I checked the same thing and it took much longer for the suction pressure to rise. I think in hindsight however, I had not isolated the low side of the compressor, and because the system had such a large evaporator (system charge was over 100 pounds of R-22) that it took forever to build up, plus it was only a small valve plate leak. But it was enough in the winter to freeze the compressor. This was not an issue in warm weather.

@@gendronhvac-r1269 Anyway, when I had time, I valved off the compressor, removed the top cover of the condensing unit, and it was fairly easy with that out of the way to replace the valve plate and head gaskets. Copeland warrantied the parts, so it was all good in the end. I heard from another tech those older DIscus compressors had known valve issues.

@@gendronhvac-r1269 As far as maybe an intermittent flood back goes, I did notice quite a bit of rust on the suction valve/motor end of that compressor, but I don't know if that's just from years of running with high humidity in your rack room. From that little rattle sound, and the obvious small high to low side leak, I think you might have a broken reed. The sound is like a small broken part. Or might be that loose bolt you pointed out.

@@brnmcc01 Thank you for the wonderful and very informative comment. It seems like I might need to tear this compressor apart. At the company I work for we typically do not do this because the systems we service are so old that if we have probable cause to open a compressor we typically replace it especially if the compressor is above 20 years old. But hopefully I'll get around to opening a compressor and showing footage of one of these little leaks. Thank you for taking the time to share your knowledge :-)

I am not sure, I am guessing to save on money . I'm guessing it's probably some kind of option Or something.

No I don't do in-person training :) I just do my little KZfaq when I have time

@@gendronhvac-r1269 sad but thx

No but you can ask questions in the comments and I will try and respond