capillary tube clogs

[hotrodluvr]

Can anyone tell me what causes cap tube clogging besides debris? The problem seems restricted to POE oil and R134a. Is there a prevention?

[monkey spanners]

I remember reading about something called 'metal soap' caused by a chemical reaction within the system.

[Chunk]

Hi.I read somewhere that this is a common problem with R134a and they found it was due to dirty condensers and high head pressures.As for a prevention i can only suggest keeping condensers clean. http://www.patentstorm.us/patents/59...scription.html

[monkey spanners]

This mentions metal soap

http://www.patentstorm.us/patents/59...scription.html

Its also mentioned a bitzer report

Cheers Jon

[powell]

Can anyone tell me what causes cap tube clogging besides debris? The problem seems restricted to POE oil and R134a. Is there a prevention?

The number one problem would be heat. Prevention would be to keep the system clean.

If you had a leak and there wasn't a LPC then moisture could also enter the system which along with the heat produced would break down the oil.

[Tesla]

Yes Chunky Monkey
I agree - high head temps are the cause of this even with r22. It forms a coke like black substance in the wall of tube. maintenance and clean condensers is the cure.

[davej]

when 134a was first being used in bottle coolers and small fridges we had lots of them blocking, when we sliced open the cappilary we found a white wax type of restriction which would if left off long enough allow flow again until cabinet reached temp and would then again block.always ended up witha new evap complete with cappillary.