Thanks for the explanation.

+Michael Hoffmann Makes perfect sense now. Thanks :)

Thanks!

Yes. Unfortunately on smaller package units with no receiver there are no sight glasses. They are critically charged.

Learn something new everyday. Thanks for the explanation.

I was in the trade for 12 years. And seen a lot of fails due to power spikes and drops on 3 phase . Train units are good . Well thier bigger stuff like 120 000 btu units . Biggest problem is usually lack of maintenance. LP slug back is the number one compressor killer that I have found .

+NZshooter shooter There are 2 other units on the roof. One twin to this unit and a Carrier. Both units were fine. We do the maintenance here so it's kept clean. One thing Trane didn't put in these units was a freeze stat. Customer turns A/C down to 60 degrees because as you know that makes it work faster and the coil turns into a glacier letting all that liquid refrigerant dump right back to mr. compressor.

Compressor starts slugging liquid and washes lubrication out of compressor, bearings fail and possibly causes shorted winding from metal shavings or overheats winding till it burns.

If I saw that type of upper bearing failure, I would be looking at a lubrication problem. Going by the serial date and video date, I would wonder if you should put on a crankcase heater to keep the refrigerant from migrating during the off cycle. But, that may be one of a number of factors that seem to point towards a lubrication problem with the upper rotor / crank bearing.

They have to last at least 5 years. That's the length of a manufacturers or extended warranty.

Interesting. Never heard of them doing that. Most I've ever had to do was send thee compressor back. Usually they just need the tag.

Jim, a "screw" compressor is a totally different process than a "scroll". The unit in the video is a "scroll".

+Steve Paxon After doing the knuckle buster treatment so many times they get cut out and new ones go in. Looks better and takes less time for me to cut them out and put new ones in than try to fight with it.

no. It's called a "floating seal". Its job is to get forced upwards against the muffler plate and to fall back down if pressure drops too low to prevent the compressor from running into a vacuum.

They are quieter and more energy efficient. In my experience they're a bit more temperamental with oil return and don't tolerate oil loss (due to leak) as much as a regular reciprocating. 12,000 BTU's = 1 Ton of capacity. Most window units for 115v go up to 1 ton anything over is 230v. Tonnage requirements are based for window units on room room square footage. A central a/c system would also include things like average outdoor temp, # of windows, insulation thickness and type, exposure of house among other things. A commercial building will also take into account occupancy and I. the case of a restaurant, kitchen equipment. There are a LOT of shortcuts and fudge factors here. Basically too small a system and it won't get cool enough. Too large a system and it won't run long enough to remove the moisture from the air and you get that cold clamy feeling.

+Halligan142 Cool! Thanks for the information. That clears things up quite a bit.

Not really, no. HVACR Videos channel has some good videos of exactly where to cut and how to minimize shavings.

It could possibly be bad oil return. If the unit hasn't started in a long time (all winter season) there is a possibility for the compressor to be somewhat noisy for the first few minutes of running until the oil starts to circulate through the system. This is especially apparent on units with the air handler lower than the condensing unit. Oil will migrate to the lowest warmest spot.

Thanks for your quick reply.Ended up being a bad contactor shorting out. I really liked you video like all the others! Thank you.

After seeing your vid seen an Australia guy power one up with the top off.Was very cool and informative.However you got to the guts to the bottom.5 gold stars to you sir.

@Preston Murphy maybe I should rephrase the question.. can you run a scroll compressor to pump a units refrigerant back into the condenser without damaging the compressor? Can you draw the suction line right down to 0 and shut it off without damage to the scroll compressor? But at any rate I'm curious where this arcing occurs that I've read about. If ya don't know that's ok

KELLY ANDERSON; The problem with any compressor running in a vacuum is that there is low, or no flow. This can cause several problems. In the scroll unit, the vanes in the bottom of the shaft- the metal ones IN the shaft- can't pump the oil effectively. The refrigerant is drawn in and takes oil with it. Lack of lubrication is the mode of failure for the majority of these compressors. The plastic part at the bottom of the shaft that was broken off while removing the shaft doesn't pump the oil. It is an oil agitator. It's purpose is to stir up the oil to prevent the refrigerant from getting absorbed by the oil, which makes it pretty much useless. • If you use the compressor to pump down just one time for service, ie: replacing an expansion valve, you're not going to hurt it. Just keep the run time as short as you can. Remember, oil travels with the refrigerant and sprays all over everything inside the compressor when it gets to the compressor. • One more thing to note is that the refrigerant on medium and high temperature systems is what cools the motor. The easiest way to overheat the windings is to run short on refrigerant!! No flow means no cooling!! Poor flow means poor cooling. Just as humans are air cooled, they need refrigerant flowing to cool the windings. • Think about this experiment: Put a human into a small insulated box that is air tight with only a way to breathe provided by some sort of tubes etc. Cause of death? Hyperthermia. You will 'easy bake' to death. • So does the motor in a sealed compressor with no other means to cool itself. • Keep scroll compressor'd systems fully charged!! Overcharging can cause damage in any system of course! In a scroll, the liquid floodback causes one-sided wear as the liquid places excess pressure on the opposite side from the intake. That's what it looks like happened on this unit. Plugged up air filters, dirty coils, running in low ambient, are usually the culprits. "Compliant" just means that the compressor will tolerate floodback for extended times, but that doesn't mean that it SHOULD be run flooding back indefinitely!! •••••Great video though!! BTW: The large seal assembly is so that the compressor can be assembled blindly at the factory. You'd have a tough time lining it all up for the final weld without it! The Matsushita scroll has the outlet line through the side of the case and eliminates this component. The internal blow off is attached to that outlet line in the uppermost casting.

@@johninmilford7719 thank you so much for all that info!!! I will be going back a rereading this again to make some notes!! But your info cleared up much of my questions!!!

Honestly in 15 years of doing this I've never looked at the RPM rating on the compressor tag.

I've seen amperage monitoring by an onboard computer on much larger systems and on a few inverter driven compressors we have in a couple experimental units. Usually it comes down to price. This is only a 5 ton unit. You can build a ton of safeties into the unit to account for almost every possibility, but if you have to then sell that unit at 10-15k more than a competitor then who is going to buy it. There is an internal thermal overload that is technically supposed to prevent this from happening, but it's an automatic reset.

It is internally thermally protected, but if it was locked rotor all I would have done is heat up until it tripped, cool down, and start the process all over again until it finally popped.

since there is no check valves these are worthless to try to get a vacuum out of

See my explanation above. They are not good in a vacuum situation.

Yes burnout

@@Halligan142 Thank you

I mean why the sudden pressure drop with a bang.

Nah. His drill. Got punished for that one.

+Halligan142 same same, I wanted to see what was behind the black screws and springs and brushes flew everywhere. Couldn't find the second brush so I put it back together with the spring touching the armature. He knew exactly who to beat on when his drill looked like the 4th of July...lol

+C Thompson Oh yeah burnt oil is tasty stuff. This was in a 5 ton package unit with no previous leaks. It was actually siezed. I had to remove the bronze bearing ring to be able to turn it by hand. It would turn and lock in the same spot no matter the rotation. I always check contactors on compressor changes. When in doubt it gets changed. Small price to pay to protect the most expensive part in the system.

Actually it's a 3 phase compressor so no starting components. If you look there are no wires and no provisions for wires to be connected to the plastic.piece nor inside the sump where it was sitting .

+gh778jk It's our standard measurement for heating and cooling capacity

The unit has fixed orifice metering devices. We used Rx-11 flush to flush out the system and installed a new liquid and a suction line filter dryer. We also made sure all the pressure controls were working correctly. We got it running and they'll only be using the A/C in the unit for the next month or so until the cold sets in. In the spring we will go back change the dryers again and perform another flush if necessary.

Thanks mate. Do all new units have such bushes, or do some come with roller bearings?

+Marcel Timmers Everyone I've seen has bushings. They're built to be cheap and last 5 years.

Sleeve bearing perform well in situations such as inside a compressor because there is a constant spray of oil to keep the metal from ever touching the mating surface. That's the case in many reciprocating compressors too! •••The caveat is that if you run short, over charge, or do anything else to change the way that oil flows to said bearing, you're asking for trouble. (Your car's wheels don't have means to constantly and reliably lubricate their bearings, so, you're right, that would be a poor choice. Bad comparison there. •In ANY bearing the main goal of the lubrication is so that the mating parts, don't "mate" at all! There will be a film of lubricant between them.

+Palcoscenico Si C'è. E ' l'olio minerale . Tutti i nuovi compressori utilizzano olio poliolestere .

That's what I'm thinking. I"m just an engineer, not a tech but I'd expect the scroll valve to spin, not wiggle.

What a dick

Douchebag much?