Freezer with capillary tube clogged

[VanMarco]

Hello.
I have this freezer that had the compressor seized so i wanted to replace the compressor and use it again.
When i put the vampire valve, I read merely 10psi of pressure (this is a R600A system)
So i figured? leak? i proceeded to install a proper Schneider valve and vacuum it. It held vacuum. I even pressurized it with air at 80 psi, also held pressure.
Bought the new compressor, changed the filter and installed it. Again, held vacuum. So i proceeded to add the 68g of refrigerant, and turned on the compressor. It made a weird sound, and i saw the gauge go negative, at about 20" of mercury, so i shut it off immediately (it ran for like 2 minutes).
I figured I may have messed up the brazed joint of the capillary which MAYBE, i did.
Also when i added refrigerant, liquid, pressure rose to about 10psi, but even as more refrigerant came in, pressure did not rise, which by itself was a red flag. It is many years I don't do these fixes, I used to work as a helper, so my memory is a bit fuzzy.
After a while i went to turn on the compressor again and it would not start. Thats when I thought "hydro-locked".
The refrigerant got "squished" in the condenser coil and locked the compressor. As i suspected either the capirally or the filter itself i brazed I may have messed it up, i cut away the filter, and a jet of refrigerant came out. after, the compressor could be started. The capillary itself, after i cut away a good 2" of length, i could see refrigerant come out, and air being aspirated when the compressor was turned on.
Now, in theory, all i need to do is buy a new filter, and re-braze both sides properly. I did cut up both filters "just to see". The one i brazed in, MAYBE, it was possible braze went into the capillary, but i am not 100% sure on that one. The old one, on the little mesh that's inside, it has a blueish-purple-ish colour, sign it may have over-heated?
Is it normal to find traces of oil from the capillary tube?? What is that causes the capillary to clog? It's a 25 years old freezer, but still it should not mean anything. To me, it seems over-heating. is the capillary "safe" to assume that it's not clogged anymore, as i could see gas coming out strong?

thank you in advance

[skarrs71]

pressure tested with AIR? put your tools away Sir!

[VanMarco]

I have tried everything. Heating the capillary tube while blowing refrigerant, soldering a schnaider valve and trying to allow liquid refrigerant from it, hoping the compressor would take it, nothing. It's clogged.
How long is this capillary inside, on average? a few feet? meters?

[Brian_UK]

A 25 year old freezer running on R600a, sounds a bit of a mismatch.

Possible oil contamination now that air has been injected into the system along with whatever oil mix may be in there.

[Rob White]

I have tried everything. Heating the capillary tube while blowing refrigerant, soldering a schnaider valve and trying to allow liquid refrigerant from it, hoping the compressor would take it, nothing. It's clogged.
How long is this capillary inside, on average? a few feet? meters?

A lot has happened to this little freezer and it requires a lot of attention and good quality tools and equipment
to ever get it going again. I don't think you have been using the correct methods and only made the thing
worse.

Capillaries can be anywhere between 1 metre and 4 metres long. Small systems like yours would typically have one about 1.25 to 1.5 mtrs long and half will be outside and half will be inside, possibly even inside the suction line.

Air should never be used on a refrigeration circuit and vacuum pumps are used to ensure the system is ready
for the refrigerant charge.

In your case I would say that the oil has reacted with the refrigerant and dryer to block the capillary and that
either caused the compressor to fail (if the compressor did actually fail) and you have then added contaminated
oil, air and refrigerant into the system to finish it off.

To replace the capillary requires exact measurements and comparisons of the diameter and length of the old one.
A new could be purchased from the manufacturer but you would just be putting it into a baddly contaminated system.

It needs a professional flush and a purge from both ends with Oxygen Free Nitrogen OFN and to do that the suction need to be removed from the compressor. Once purged a new dryer, probably a new compressor and new oil will be required.

Before the new refrigerant is added the dyer and suction need to be reattached while purging with the OFN to
prevent further contamination and then a good deep vacuum with a proper refrigeration grade vac pump to lower than 2 Torr or less than 2000 Microns. Then the refrigerant wants weighing back in.

All done in clean, dry working environment with quality tools and equipment.

taz

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[VanMarco]

All done in clean, dry working environment with quality tools and equipment.

taz

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Yes, too bad this is romania
Also, maybe i am not clear. the compressor was and IS, 100% seized. Nothing that i did, caused it to seize. it seized because it over-heated. Oil must have vaporized and clogged the capillary, and eventually the compressor seize. I do know the effect of air in a refrigeration system, i am not that stupid. I pressurized with air because I have nothing else to try, I did so because both the compressor and dryer filter were to be replaced.
Going to buy another second hand one, would cost too much, as a matter of fact, it would cost an entire month's worth of salary here, and pigs are about to be slaughtered, so i wished to fix this.
Capillary is pretty cheap. All that i fear is that there is MORE oil and junk, albeit the vacuum pump has pumped out quite a bit of it. *before i did the "air" test, i let the vacuum pump run for a good hour
Sorry to disturb.

[Rob White]

Yes, too bad this is romania
Also, maybe i am not clear. the compressor was and IS, 100% seized. Nothing that i did, caused it to seize. it seized because it over-heated. Oil must have vaporized and clogged the capillary, and eventually the compressor seize. I do know the effect of air in a refrigeration system,

i am not that stupid. **

I pressurized with air because I have nothing else to try, I did so because both the compressor and dryer filter were to be replaced.
Going to buy another second hand one, would cost too much, as a matter of fact, it would cost an entire month's worth of salary here, and pigs are about to be slaughtered, so i wished to fix this.
Capillary is pretty cheap. All that i fear is that there is MORE oil and junk, albeit the vacuum pump has pumped out quite a bit of it. *before i did the "air" test, i let the vacuum pump run for a good hour
Sorry to disturb.

You are not disturbing

If you do use pressure (air) disconnect the suction from the compressor and blow it back in the opposite direction. The capillary can be accessed at the dryer end which is the normal direction so anything blocking it will be in that direction. If you blow it from the suction end it is sometimes possible to blow the blockage back out the way it came.

Just be careful not to over pressurise the evaporator because I have seen them blown up like a balloon when pressurised too much .

R600 at 32 degsC is only just over 3 barg so be careful not to over pressure it.

Rob

** Ps sorry if I made you feel like that, it was not my intention

.

[VanMarco]

Hello. I took out the evaporator, The evap is plastic coated steel.
I have found a "mystery" part, which look like a filter, but i am not 100% it is. it could be though.
The capillary passes inside the return line, goes through this, and then goes to the evaporator access point.
I am not sure if they passed the capillary through that for the convenience of not having the capillary be outside of the evaporator until it reaches the access point, or it is vital that it passes in there. Do you have any idea what that is? THe orange is the capillary line, the purple is the gas flow.

https://i.imgur.com/uM9hyRC.jpg

thank you so much!!

[Rob White]

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That is a suction accumulator and is there to prevent any excess liquid returning to the compressor.
It's quite important. It basically is a tube with the outlet higher than the inlet.

Rob

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[VanMarco]

Thanks a lot, it makes total sense. is it vital that the capillary has to pass through that? thank you

[Rob White]

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No not vital but it helps with heat exchange.
If you wrap the capillary very tight around the pipe it will give some heat exchange.

Rob

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[Rob White]

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I have replaced capillaries in the past and you can never get it the way it was designed in manufacturer.
you basically have to make the best of it but because you have exposed it fully you will be able to wrap it
tight all the way up the pipe.

Rob

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[VanMarco]

there was excess capillary on the outside too, the total length is about 200CM, cm+/cm-. thanks a lot

[Rob White]

there was excess capillary on the outside too, the total length is about 200CM, cm+/cm-. thanks a lot

That is normal.

Normally in a big loop and either tie wrapped or wrapped in a tar coated bandage.

That loop is for maintenance and repairs and just needs to be kept safe and not knocked.
The amount of times I've dealt with a capillary tube that has been damaged..........
If I had a £ pound for each time..... I'd have a few pounds

Rob

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[VanMarco]

Now that i pulled out the evaporator, should i do any cleaning of the insides? in theory, gas flow direction should prevent any further gunk from plugging it again. Gas goes through capillary, expands, and eventually goes back to compressor through return line. gas coming in from the condenser, passes thru a new filter/dryer. so I assume, the evaporator should be my last concern for "gunk". the condenser, sprayed out a lot of oil the first time that i realized the capillary was clogged (refrigerant, and oil), afterwards, i tried blow some pressure in it (refrigerant, not air) but no oil came out again. Also the first vacuuming that i did, quite of bit of oil got sucked out.
new capillary arrives tomorrow or day after tomorrow and yes, i carefully measured it, 2.0mm x 0.8mm. What kind of tape is used inside freezers? considering a technique for removing stubborn adhesive is freezing, that leaves just specialized products. On hand, i have the following. Aluminium tape, and a special 3M duct tape designed for outdoors, military green colour, it resisted +40C and also did not detach from where it was even in winter, whereas -20C -24C is possible and often the rule at night.
Mr rob, you have earned yourself a slab of bacon, too bad you are too far!

[VanMarco]

I changed the capillary tube today, re-put everything back together. before vacuuming, i checked there was a flow, and there was. I vacuumed for half an hour to 29.7 inhg, then put refrigerant. I suspect i may have messed up last part. I used a kitchen scale, but i am not sure 100% how much went in. i stopped at the rated 68 grams, yet, albeit the freezer was cooling, after a while i started to read slightly under vacuum. I added A LITTLE BIT More, and i did see it running at about 2/3 Psi, but the temperature drop inside the freezer was slowing down. All i can do now is wait patiently for the pressure to equalize and reference with the pressure/temperature table. At the beginning, i registered about 20s between each 0.1C drop, then when it approaced 2-3C, it went up to 30s. is this normal?

Thank you.

[Brian_UK]

You should not make any adjustments until the unit has stabilised its temperature as the component parts are designed to function at design temperature.

[frank]

Sounds over charged to me but pressure and temp checks should confirm

[VanMarco]

Yesterday night, temperature inside = 4C according to table should read 11.48. I read 15. this morning, temperature inside, 11C, should read 18-19 still read 15. I think the instruments are not helping me, even though it's just pressure i am reading.
When it starts, 4/5 of the condenser top coils get hot, and as it keeps going, progressively only the first 2 remain hot.
temperature as it approaches 4C, i get about 4 and a half minute per each degree that it drops, when it s close to 1C, this time greatly increases. My only clue is that the bottle with the gas seem way too light that just 68g went in. there is no tare written on it, so i am not sure, but it is possible 100grams went in. is it over-charged, or undercharged? Now i just let it go to about 2C in 1 hour i will go read pressures again.

[VanMarco]

I don't know why gauges are not helping, all I know is that it is over-charged. the suction freezes pretty bad. I also know because I released some, and it started working much better.
Why the gauge don't help, is probably because, it is over-filled. I release some, pressure drops for a while, then goes back to the exact level. I suspect a lot of extra liquid is there and that "fools" the gauge. I may be wrong, though. I confess, I did not study. :P

[VanMarco]

I bled some more refrigerant, now it reached -20C
I recorded times taken between each 1C drop. last being -17.5C
-17.5C 3.45
-16.5C 3.20
-15.5C 3.20
-14.5C 2.53
-13.5C 2.53
-12.5C 2.25
-11.5C 2.25
-10.5C 1.58
-9.5C 1.58
-8.5C 1.58
-7.5C 1.49
-6.5C 1.58
-5.5C 1.33
-4.5C 1.13
-3.5C 0.36

Seem pretty consistent to me, same with the so called "diminishing returns" as temperature drops and drops.
The condenser has the same temperature on all coils no imbalance anymore. return line is partly frozen where it comes out, where i didn't put back the insulation, no longer freezing on the compressor port.
The only thing I do not like particularly is that can hear a slight rattle from the compressor, very faint. Also, i have no idea how much gas is in there, it may still be slightly over-charged. it took about 40 minutes to go from +10C to -20C

[VanMarco]

I don't know what gives. to avoid doubt of having it under or over charged, i vacuumed again, and put the correct charge in. exactly 68G. It seemed like it was going great, it reached -10c and suddenly, temperature started rising, all the way back to -7C.
My only theory is the unit it still over-charged, by the virtue of having replaced the original compressor with a slightly smaller one
Original
https://store.danfoss.com/gb/en_GB/C...K-2/p/195B0183
Replacement
https://www.secop.com/fileadmin/user...esd564h102.pdf
Original Free gas volume [cm3] 2310 cm³
Replacement Free gas volume in compressor 1660 cm³
Even though both say max refrigerant charge 150g.

Sorry for all the hassle.

[RANGER1]

Some tips might be useful

R134a Recharge Guidelines (coastalclimatecontrol.com)

[Brian_UK]

When the compressor manufacturer quotes a maximum charge quantity it is the maximum that can be allowed into the compressor.

It has nothing to do with the operating charge required by the refrigeration circuit itself.

If the charge goes above that amount then there is a probability that compressor will be damaged due to pumping liquid.

[VanMarco]

Some tips might be useful

R134a Recharge Guidelines (coastalclimatecontrol.com)

Aw, thank you very much. That is what i was looking for
Will let you know!

[VanMarco]

All good and dandy, but, I was told "don't fix it when compressor seizes, it dirties up everything", and I did not listen, because my past experience 15 years ago on how many were easily fixed by just changing the compressor, told me "i can do it"
In retrospect, it may have better that i bought another one. Now, after days of troubleshooting and a good 90 usd,i feel bad to toss it, i will try once more.
What i suspected, was "clogged again", and i was right. I saw some video on how to flush the condenser, and I did. At first only some cloudiness and some weird, but magnetic fragments came out. (I used first xylene, then rinse more with rubbing alcohol 98%) after some rinses, and like "heat while push compressed air in", this came out at once
https://imgur.com/a/GVcddim
the dust is highly magnetic. definitely smaller than the screen in the filter drier
All i can try now, is after rising, put a new filter and try again. I suspect also the evaporator may be dirty, but i am not entirely sure.
After this, if it clogs again, all bets are off.

[Brian_UK]

Yes, in the "olden days" a compressor swap was simple because the refrigerants were single element gases with stable oil.

Nowadays the gases are often mixtures that play havoc with any cross mix oils and are more sensitive to the system running over limit temperatures.

If, when, you succeed then consider it a job well done.

[VanMarco]

Today i put a new filter drier, reinstalled everything, made sure capillary isn't clogged, and put EXACTLY, 68G of refrigerant in, 100%
It started good, then arrived again at -9C and stopped cooling. Why this number specifically, i have no idea.
the return line is frosted at about 3" away from the compressor, according to the above website that means slightly overcharged.
What could possibly make a freezer stop cooling at a set temperature?

[Brian_UK]

Give it time to achieve design temperature.

Is the unit insulation still in good condition?

[VanMarco]

I wanted to thank you for all the help. I did not try to let it go more today, i set it between -2 and -6 and put 10kg of water in, it does freeze, slower than a "normal" freezer, but it does the job-ish. For some reason, sometimes especially toward the lower temps, i hear some creaking sounds from the compressor. it works at around -5" of mercury. Starts, stops, don't know how long is going to last, at this point, "amen". I might have inadvertely made some modification to it. Maybe that capillary coming in that evaporator liquid storage thing that no longer goes through that, maybe, i put too much capillary, I honestly have no idea. kinda looks like when a regular fridge starts to go much colder normal operating temperatures because of faulty thermostat. the ice, is just a test, after that, we will use it to just keep freshly harvested meat at +2/+4.

[VanMarco]

Hello. Update. I had the freezer running for a day wiith a target temperature of -6C for 24 hours. the day after, i moved the target to -10, then -12, then 15, then 18, considering the 10kg of water inside needing time to freeze. it did work. Today i removed the thermal mass of the ice, opened the door and left it going up to +1C, then fired it back, in about 50 minutes it reached -18C. I suspect there was, or there still is some restriction but not complete occlusion. the first 13-14C it drops, it drops 1C in around 2 minutes, the last between -15 and -18, it takes longer, at around 4-4.5 minutes. The creaking sound has ceased, i just hear it in the first 5 minutes at start up.
The only thing that i am not entirely sure is this. At 0C, pressure reads about 1psi. it goes to -5" of mercury up to -10C and then drops to about -10/11". assuming my instruments my are not lying, which i think they are not that means a temperature of -40~-50C, that referred to the temperature of the evaporator. if they are not lying, either I added too much capillary, or it's restricted.
It is entirely possible some junk was left in the capillary, and the hot liquid, essentially butane, is washing it.

[Rob White]

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Domestic and small commercial sized fridges and freezers all suffer from the same problem due to design.
The problem is the capillary has no control so it has to be pre-set to the running condition of it's design temp.

That means that a fridge designed to store food at +2degsC will not be operating correctly until the fridge
reaches the design temp.
It is the same with a freezer designed for -18degsC. they are only operating when down to temp.

Remember that the evaporator temperature (pressure) will always be at least 10degs lower than the actual product temp.

If they had an expansion valve or other control valve to regulate the pressure they would work more efficiently but they cost money and these fridges are built to the lowest / cheapest spec possible.

Imagine a car trying to achieve 100 mph from a standing start, if the engine had no accelerator and no gears in the gearbox. It would struggle for a long, long time until it built up enough speed required to cruise at 100mph and the fuel consumption with be extremely high.

That is your freezer it has a one size compressor (engine) and fixed capillary (no gears in the gearbox) and you want it to pull down to -18degsC from a standing start of +10 or +15degsC.

The load on the compressor is astronomical.

Now imagine changing that car engine out and swapping it for an engine that is slightly smaller....

And you wonder why the poor thing struggles

It's almost like you have attached a large trailer to the car and expect it to preform the way it did.

Let it run with a fixed load remember the heat load of water from +15degsC to 0degsC, then from +0degsC to -0degsC and finally from -0degsC to -18degsC is actually three steps. The amount of energy required to cool the water by 15degs and the energy required to cool the ice 18degs is only a fraction of the energy it takes to freeze water to ice at 0degsC.

Rob

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