View Full Version : Clearing Restrictions with R22.

29-07-2003, 09:35 PM

I have just started a new job with a large domestic refrigeration company in London. I have only recently left the Army after serving seven years in the Royal Enigineers. I am quaified to City and Guilds level in Refrigeration and A/C as this was my trade within the army, although I hardly ever had any hands on experience during my time here.

I was pleased to find this forum as I was hoping people could help me with some of the simple questions I may have from time to time! Since I have been in this job I have frequently found restricted appliances in both R134a and R600a systems. Can anyone help and offer me any advice on the best way to clear these and prevent them from reocurring. Remember these are small domestic appliances and not large commercial systems.

Many Thanks,


29-07-2003, 09:41 PM
Hi Doc:)
R22 would not be the thing.
1/ Insufficient pressure.
2/To clear a capillary you would have one side open to atmosphere and you would be braeking the law venting R22
3/Mixing gases, although proper evacuation would cure this but again you would be venting R22 when running the pump.
Better to use oxygen free nitrogen as per pressure testing.
Regards. Andy:)

29-07-2003, 09:55 PM
Hi Danny :)

Unwittingly, you have reopened the small-appliance-restricted-cap-tube sore that WAS festering on the arse of everyone here! :D


FIRST - the key thing is to determine where the restriction is -

If the filter-drier or strainer is restricted - replace it. NOTE: be sure to pierce the drier body near the inlet so that you do not injur yourself when sweating the drier out, or cut the drier out as opposed to using a torch to remove it.

If the cap tube is restricted, many suggest that the entire cap tube should be replaced, then complain about the complexity of such a chore relating to the construction of (disposable) appliances. :p

Many brag about the efficiency, expediency, and ease of clearing restricted cap tubes with the use of a hydraulic tool that pushes an expendible bit through the cap tube hole.

Even so, with any of the methods, a primary concern is the cost to the end user for such a repair (might be only feasible under factory warranty in some instances as far as the owner is concerned). Mind you that the appliances are becoming cheaper and cheaper to replace, as such often a repair of this nature will not be feasible. In that regard, you find many who are self-concious regarding the "waste" of material for the sake of saving the cash for a repair of a possibly nice machine (except for the fatal failure), as opposed to repairing it and prevent the destruction of the Earth from the evil human who fills up the landfills. :p

so, there ya' go.... and welcome aboard.


03-08-2003, 05:26 PM
Many Thanks for your replies.

Unfortunately we do not carry nitrogen at the moment although apparently this may change in the near future. After cutting the capillary after the drier would it be possible to use a reclaim unit and actually blow air through the service valve to clear any restriction or would this cause damage to the compressor.

As you say herefishy it is alot of work when new applainces now are so cheap, but the company is contracted to most freeze/freezer manufactures and many of these problems occur whilst they are still under warranty so we have to give it a good go to fix them before writing them off.

Many Thanks,


03-08-2003, 06:11 PM
forget blowing anything......

if you suspect a blockage then you must first fit another line tap to the 'high side' and re-claim the refrigerant.

then remove the drier and check if it's blocked
(a simple blow through will sufficice -but do wait till it's cool ;-) if not then it must be the cap....all things being equal.....

forget about blowing it clear with anything -

you had around 150 psig pushing it and and 20" vac sucking it but that didn't clear it so unless your going to 'up' that by a factor of ten -forget it....

condenm it and get a new one sent down from the manufacturer

then you can have hours of endless fun fitting the new one..



03-08-2003, 08:32 PM
Originally posted by Doc
Unfortunately we do not carry nitrogen at the moment although apparently this may change in the near future.

Hey, welcome Danny..

If your firm is not letting you carry nitrogen then they are not expecting you do be able to work correctly.

*air* should never be used as it encourages moisture into the system. N2 is required whenever brazing is carried out and of course for pressure testing as well.

I suggest you have a little word with the guv'nor :D

Good luck in civvies :)

04-08-2003, 07:07 AM

Having worked on domestic appliances for high end companies many years ago, we never attempted to unblock a cap tube if the appliance was still under warranty, we ordered up a new evap plate and suction/cap tube assembly and replaced the blocked one.

Good luck


09-10-2003, 12:50 AM
Hi Doc,
Sorry, but i have to agree with most of the others.
Blocked capillary tubes are a nightmare especially on R134a.
High pressure nitrogeon is the only way to clear it and if the system is in a bad state eg pot bun out, this probably wont work or only work short term.
If the system is in that badder state to block the tube, Scrap it.
I know this isn't enviromentally friendly but how good for the enviroment is using loads of diesel keep goin back to the unit when it blockes up again.


Ray (R134a Fan Club NOT !!!!!!!!)

09-10-2003, 01:24 AM
Hi Danny,
when I did a lot of domestic work, found that the best way to clear capillary is the use of a hydraulic tool. You need to find out why your capillary is blocking soo soon you say that the system is under warranty (what 3-5yr) could be that they are not using the right desiccants in there drier think it should be XH9, but then R-134a any thing can happen.



P.S When using hydraulic tool make sure you go from the capillary end not the evaporator, had seen it done from the evap not a pretty sigth. :-)

09-10-2003, 06:34 PM
Hi guys,
Sorry to iterupt your coversation,
Why bother with cleaning blocked capillary tubes?
I always keep three rolls of different sizes of capillers and a chrt gas/ length/ capacity. its fasrer to change, no special tools and get paid faster.

09-10-2003, 07:22 PM
How about posting the Chart gas/length here so we can download


10-10-2003, 03:34 PM
Hi Aiyub,
Its in bad state ( at the bottom of my tool box) but I will get it clean, scan it and post it!!