Diagnosing a damaged scroll compressor with very low capacity

It is very rare for a scroll compressor to lose capacity. I made this video, because this is the first scroll compressor that I have seen with partial capacity. I show how to diagnose the low capacity and examine how the relief valve inside the compressor is the problem.

[@flyinghigh5531]

Long time down the road but thank you. I ran into a scroll doing this same thing for a walk in freezer. The compressor shuts off on low pressure when the solenoid or outlet of receiver is closed. Typically for freezers, LPCO are set from 5-10 psi with 404a, and this compressor would only pull down to 14psig, no matter how long the liquid line was closed. The defrost heaters are interlocked with the compressor shutting off, so the compressor never could shut off and run hot, and defrost wasn’t working. I will have to cut this one open and look at the bypass

[@jeffersonwlafitte]

Probably the best scroll video I have seen! I have the exact same problem on condenser we've had recalls on. Thanks!!

[@jessehoffman3269]

Interesting video thanks for teaching me something new and useful !

[@mikakey55]

Great explanation! Thanks for the knowledge.

[@knighthvac4876]

Great video , thanks for posting it!

[@damarcojackson1005]

That was an excellent video...thank you...👍👍

[@jimgill5706]

Very good video. Thanks.

[@jddr.jkindle9708]

Nice catch.

[@ryang6222]

Helped me! Thank you!

[@fredrosas2575]

Great video thank you

[@rcinfla9017]

One thing to check for when there is low compression is oil logging in evaporator. Less than about 50% compression can result in net loss of oil return. Oil travels well in liquid refrigerant but has to be .'blown' back to compressor input by vapor gas mass flow. Drain and check amount of oil from oid compressor. Should yield 85-90% of spec name plate oil load. Field replacement compressors come with 10% less oil load in sump compared to new system to account for a normal 8-10% of oil distributed in system. They have a different part number suffix designating it as a replacement compressor. You don't want to end up with too much oil with new compressor pulling back all the previous oil logged in evaporator coil. One sign is hard starts on new compressor after 30 minutes of initial run time which is enough run time for new compressor to pull all the original oil back to new compressor.

[@mikhaielj846]

Great video

[@harryhathaway1086]

never thought about using an infrared camera but now that they're coming down in price if it's a viable tool to have on our truck

[@raulhodge3314]

I have a scroll, pumps down, but has low head and low suction, R-22, I over charged it but but pressures still low on both sides, low amps too rated 29, only pulls 21, never seen this before, Copeland tech support didn't know either, do you think the scroll turbine could be weak?

[@antoniosantiago2770]

Great video. Can You show me the load calculation method you mentioned with wet bulb etc. thanks for sharing.

[@stevengilber1153]

Nice job

[@VinniePepperoni]

Great video, hey would that bypassing discharge heat the thermal protection up to the point of tripping it and shutting down the compressor ?

[@NathansHVAC]

The partial capacity was able to keep the compressor cool enough to stay on line.

[@electricboyo]

I had a compressor develop a stuck-open internal relief valve many years ago in a small commercial building I own. I ended up replacing the outdoor unit because it was very old.

[@z06rcr]

Nice work. I've occasionally encountered partial relief valve failures that have a characteristic high pitch whistle but never a full open fail. BTW How go like the Seek Reveal? Looks like a nice little tool.

[@NathansHVAC]

I love the thermal camera. However, I did run the battery down once and the processor lost it brain. I had to open the camera to unplug the lithium battery. I couldn't find a reset button. But, it is probably better to call the factory than open it unless you are good at working on very tiny electronics. I doubt a lockup happens very much. Other than that, it runs perfect. I use that too so much that I carry it in my tool bag.

[@cubanito725]

good video..thanks.!!.

[@fixithvac9360]

Good video! I would check the ratio only. Some day I will get a thermal camera :))

[@denrayr]

Have you ever made a video on the spreadsheet? My inner nerd perked up a bit when you mentioned it haha. Where did you get the formulas from? Is there a good reference book that you recommend for such formulas?

[@matthewforestieri6895]

subscribed, thanks

[@user-tr7hp1de8u]

Good call👌

[@b1conis]

I have a scroll compressor that will not do it's capacity but will pump down. Adjusted the Subcool to 4 degrees and the the Super-heat went to 38 degrees. 158 suction and 290 head 410A refrigerant. Added refrigerant suction continued to go up but higher superheat. This compressor pumped down to 30 pounds ad went off on low pressure. What if the internal relief valve is partially leaking by. If this compressor had an unloader or hot gas bypass I would think different.

[@shahidbro1]

Hi. Nathan .. thanks for your video. I got the same problem .and I changed the new Compressor even have the same problem again..r22 . suction 120 and discharge 200 psi , these was the unused Compressor kept in stock from very longer. I want to know is is possible ,the internal relief valves can be damaged when kept in stock for more than five years.

[@NathansHVAC]

You might have the wrong size metering device.

[@biblebloopers946]

So how do you know when you walk up to a unit with a scroll compressor if it's the kind that will pump down to 0 psi or only 50 psi?

[@NathansHVAC]

You will hear the internal pressure relief open on the scrolls that won't pump down. But, even 50 psi gets nearly all the refrigerant moved over.

[@poojaprajapat9183]

Pumping low so what compound I should be fill between scroll blades which improves pumping

[@NathansHVAC]

Low pressure is a refrigerant issue. Low scroll capacity results in higher low side pressure.

[@terraair77]

Scroll into a vacuum?! Is that a good idea?

[@hvacrcole]

You can use compression ratio to find that problem, the compression ratio should be 4 to 1. How you find the compression ratio is take the low side pressure and the high side pressure add atmospheric pressure to both and divide your high side absolute by your low side absolute and it should be close to 4.

[@NathansHVAC]

This one was 300+15 and 175+15 or 1.65. The new compressor was 300+15 and 108+15 or 2.6. I never really used compression ratio before. R410a refrigerant lowered the ratio alot compared to R22. A very long time ago, R12 had the highest ratios of all. 13 SEER and better lowers the ratio even more. It is my belief that the higher SEER standards have been making compressors last longer because of the lower ratios and lower discharge temperatures.

[@20antman]

Another way we test compressors is to find its performance chart or curve. You graph it's suction pressure and condensing temp. It will then tell you what your amperage should be in those conditions. It works really good especially for units that have no shut off valves.

[@UlisesPalacios]

The check valve is on the outlet of the discharge stub. The thing that you referred to as the check valve is thermal disc. I replaced 3 lg scrolls last year. On one I could definitely hear the ipr valve by passing but not on the other two.

[@NathansHVAC]

Actually LG compressors have a plastic seal that deteriorates if there is any alcohol in the system. QuiKShot can make the LG compressors fail in the first year. i was going to do a video on this subject, but I haven't had an LG compressor come my way yet. Copeland uses metal to metal for the scroll seal and not a plastic wear ring. As for the check valve: Most of the manufactures moved it to before the outlet muffler/chamber to prevent the reverse action sound when the compressor stops. Here is the diagram. yorkcentraltechtalk.wordpress.com/2013/09/07/scroll-compressors-a-primer/

[@UlisesPalacios]

That's Interesting about the lgs. I've opened a few compressors. I wanted to open those Lgs but I had to return them. Check out some of my videos.

[@NathansHVAC]

Here the the plastic seal ring similar to what LG is using. njcomptech.en.made-in-china.com/product/HbmEwdfoCskx/China-Scroll-Compressor-Seal-for-Automotive.html There are a couple of videos on KZbin about LG Compressor failures, but no one is questioning the seal ring accept me. So, it is possible I am wrong about using plastic to seal between the scrolls. I don't claim to be a compressor engineer. However, I personally just stick to Copeland compressors because the failure rate seems much lower.

[@UlisesPalacios]

I see that's an interesting design and I don't like it. Yeah same here I prefer copeland and alliance compressors which are pretty much identical. Some Danfoss compressors have an axial seal. I opened one that wasn't puming. The scroll looked similar to the lg in picture If I remember right. _plus.google.com/photos/..._

[@UlisesPalacios]

Never mind it doesn't have that seal like the lg

[@liperonus]

It's not a one way valve your hearing,it's the scroll plates slapping because there's no refrigerant, no pressure

[@LongTrout]

I am suspecting that when you charge a copeland scroll with liquid through high side while under vacuum causes internal damage with the result being equalized pressure while running....If so why?

[@NathansHVAC]

It is not that easy to damage a compressor. Pressure won't damage it. Scrolls are actually much tougher than pistons. However, it is possible to wash out the oil from too much liquid going into the suction or loss of refrigerant preventing return of the oil.

[@LongTrout]

@@NathansHVAC it is happened twice to me now. I pump the system down 2 below 100 microns and then add refrigerant 410A in liquid form as recommended by manufactured into the high side and the compressor will not function after that. I find it very odd the circumstances that these compressors failed.

[@WreckingCr3W2]

@@LongTrout that is odd, are you still charging with that method or are you now adding refrigerant once valves are open and unit has a ran a while

[@LongTrout]

@@WreckingCr3W2 you know old school method when you had a system completely empty it was completely acceptable to dump liquid in through the high side of the system to break the vacuum and get refrigerant in the system quicker. In fact I was taught that that was the only time you would ever charge your system with liquid. It is odd that when you pour liquid into the high side of these compressors you ruin them. And yet it is proper procedure with the new units to charge with liquid. I am troubled by this and would like to know what the hell happened to those two compressors

[@LongTrout]

@@audram1295 You are misunderstanding. I put liquid into the high side with compressor off to break the vacuum. It was a common practice on reciprocating compressors to save charge time with R-22 so save charge time since it is an unblended refrigerant and units are charge with gas. It is the only time proper procedure to put liquid in an r-22 system. I would not recommend this practice on scroll compressors however. I was curious as to why.