R134a Blockage

Has anyone come across capillary blockage using R134a.

A large Amana fridge/freezer only 10 months old has given up the ghost. First signs of trouble was ice in the milk and then total defrost. Had a line tap on the thing and registered suction pressure @ -20psig!. No loss of charge and after recovering couldn't get nitrogen all around the system. Seems that the capillary is well and truely blocked.

Spoke to a friend engineer and he said that in his experience this had happened quite a lot on his jobs and it appears that the gas causes the oil to floc and the capillary then "grows" a lining until there is just no free space left.

My theory is that the compressor was left open for a long time during installation at the factory and the oil has been contaminated with moisture. Can't be sure though as I haven't had the compressor out yet to do an acid test or oil test.

Any thoughts or experiences would be welcome

frank:confused:

Frank

R134 is notorious for blockages. They just pulverise the dessicant in copper spun filter. YTou see a nice white coating on the capillary tubing

I have come across many many blockages on 134A

Frank

Working purely on the domestic side i come across blockages quite often, not only r134a systems but r12 were/are just as prone, here are a few common denominators that keep popping up.

1. unit has been transported (carried tipped horizontaly) not being left to stand, this will fill the pipes with oil, once switched on will pump oil into the capillary and on to the evaporator, where a distinct sound of "rushing water" can be heard.

2. Certain brands are susseptible to blockages without even being moved. Beko (comets), Candy (Kelco) and usually happens at a young age, saying that, i have probably come across most makes in existance today that have suffered a blockage, i have found that the summer can become somewhat busier for blockages, maybe the viscosity of the oil becomes thinner?.

Anyway, the methods i use to (try!) ans cure are:

Somtimes a slight increase in the gas pressure can be enough to shift the oil, or, i have a tool that resembles a 'bottle jack' that connects to the capillary and can force upto 1500psi through the system, almost always effective but can be extremely messy when exiting the suction return line!

hope this helps

Mike

Thanks for the prompt replies - nice forum, looks like I'll enjoy it here!

Frank

Mike,

This tool that forces pressure through capilary
Care to shed some light on it
Im intrested
Lets hope its not a treasured secretive copyrighted design of yours!!!


Aiyub

No, they're nothing secret, I think firms like HRP and NRS have them in their catalogues.

I check tomorrow when at work.

Thank Brian,
Would like to get my paws on that piece of kit
Going back to the other postings, why dont manufacturers start using larger bore cap tubes. I have seen tiny cap tubes about the size of a human hair. OK, I know its to do with size of compressor and science, physics, calculations, etc
I did my own experimentation. Used large bore cap tubes, adjusted the lengths, and worked like a dream
One system which lost a compressor regularly, now its been running 10 years with a larger bore cap tube.........no prob
I hate myself now, imagine all the money Ive lost not having to trudge there replacing the motor every now and then........Grrrrrr

Aiyub there are cap checkers shown in both the HRP Refrigeration Price List under service tools and in the ITE catalogue under evacuation and charging equipment.

I couldn't seem to get too far with website searches on these two firms and I haven't got my password for Dean and Wood's site here in the office, I'll try and check with them later.

Cheers.

Hi ,I've come across this problem lots of times i do alot of brewery refrigeration and find it very common with bottle coolers using R134a when I find a compressor gone down with this fault I generally replace the complete evaporator when fitting a new compressor to the system or just the capillary tubing if it is possible to particular make/model of cabinet.

Hope this helps..

I just fixed a 134a blockage 2 days ago...NO FUN!

Although the 134a is a little thicker than other refrigerants with the dreaded POE oil (I prefer synthetic or Alkyl-Benzine oil myself), I feel that the blockage is caused by wax buildup in the cap tube where it enters the evaporator....a bit of heat from my turbo torch while the evaporator is being pressurized in the reverse direction with 100 psig of dry nitrogen straightened it out.

After that, I used R-414B (Hot Shot) for my charge and it worked like a dream!

It's available from most supply houses or from ICOR International. It's also about 50% more expensive than R134a but works without any oil change. The head pressure is slightly higher than 134a, but not enough to cause many problems, if any.

Don't you just love 134a, It's the best thing since sliced bread !!

As stated above waxes capilery tubes wonderfully.
A tip for what it's worth, braze a piece of 1/4 copper to the end of the capilery about 6" long with a 1/4 fitting on the end, spray some wd40 into the copper pipe, connect line to nitrogen bottle and blast away, don't forget to remove sution line from compressor, not that I think the small amount of wd40 will do any harm to compressor. Nomally clears capilery of most junk

Good luck

Mr Cool

Zolar,

This magic R414B gas., Do UK techs know what its called here. Its not R49 isit?

Not sure...it's a liquid comprising of 50% HCFC-22, HCFC-42b, and HCFC 124.

Zolar

R49 do you mean Isceon 49?
This is R413a
I find it a good drop in for R12 or R134a you can use it with mineral or ester oil.

mr cool

OOPS!
I meant 142b, not 42b.

Hotshot (R414b) is compatable with all oils.

I have to wonder if it isn't more of a problem with the condenser size than the oil. As Mike said above... it seems to rear its ugly head in "certain" manufacturer's units more than others.

I have found it happens mostly on reach in units with top mounted condensers. The condenser coils are usually very compact and filthy from no maintenance (yet the end-user doesn't want a maintenance agreement). I also see it more frequently on systems charged with R-404a.

I agree that POE oil sucks! (Literally!) I use Alk or Min... no POE for me! HEHEHEHEHHE!

Did you know that POE is made from/with fatty acids? It is derived from animal fats.... fish oil I think.... hmmmmm.... can't remember for sure.:confused:

Quote:

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Originally posted by zolar1
OOPS!
I meant 142b, not 42b.

Hotshot (R414b) is compatable with all oils.

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And a little bit of R600a in that mix for good measure.

the tool you are talking about is called a cap tube ,pump and chaser kit comes equipped,with different size diameter soft lead,if cap tube is clogged hook up bottle jack blow out restriction,then match uo lead size with cap tube,snip a small piece off insert in cap tube,and pump hell out of it,it will clean out any residue left.lead piece falls to the bottom of evaporator,no harm.

Quote:

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Originally posted by Aiyub
Frank

R134 is notorious for blockages. They just pulverise the dessicant in copper spun filter. YTou see a nice white coating on the capillary tubing

I have come across many many blockages on 134A

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what bottle jack tool do you refer to i need something to help me clear blockages
great post
john squibb

Quote:

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Originally posted by leonardbtessier
the tool you are talking about is called a cap tube ,pump and chaser kit comes equipped,with different size diameter soft lead,if cap tube is clogged hook up bottle jack blow out restriction,then match uo lead size with cap tube,snip a small piece off insert in cap tube,and pump hell out of it,it will clean out any residue left.lead piece falls to the bottom of evaporator,no harm.

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where do you get this tool ?

john squibb:rolleyes:

You can get one at www.johnstonesupply.com

I bought one, and ever since then, all the blockages got scared and left. Dunno why....I haven't used it yet....lol

My problem is with a commercial freezer, seems like a cap tube blockage, or restriction. I am thinking about avoiding these issues completely, and installing a TX valve. I am thinking about adding in a small liquid receiver as well. My idea is that with a TX and receiver the refrigerant charge stops being critical, more room for error and I also avoid cap tube issues.
Has anyone else tried this approach?

I have a bunch of R12 TX's in stock from 10 years ago, and according to everything I have read R409 will work effeectively with them...Anybody else experience anything different?

the tool you require is called an imperial 1003 capiliary check and you can get them from hrp about 180 quid.if thats too much they also do replacement cap kits if you tell them the hp of the compressor,low back or high back etc.they stock these on the shelf with filters attached.we found a while back that the biggest reason for choked driers was a dirty condenser!!

Quote:

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Originally Posted by frank

Thanks for the prompt replies - nice forum, looks like I'll enjoy it here!

Frank

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I think you liked it too much Frank
Brought a smile to my face reading that " old" post
:)

Hey Abe,


Who's Frank?;)


Chemi:)

Hi Chem

Im sure its " our" Frank!!
You know, the guy who likes beer.......and bikinis!!
:)