Any advice how to cure this blocked system?

I'm working on a commercial freezer with a semi hermetic compressor marked J&Hall, 4hp. There is no oil separator. I don't know which gas was put in by the last engineer or which oil is in there. The gas leaked out of a damaged tube . I charged it with 22 but the expansion valve is blocked. The sight glass shows the gas a dirty red and the smell is bad. I'm thinking I should change the oil and charge again with 22 . Which oil would be best and what would be the best way to clean the system? Or any alternative advice ?

Pull the entire refrigerant charge and dispose of.

Check TEV data to determine refrigerant type for Element charge.

Pull oil sample from crankcase and test for acid with Sporlan acid test kit. You may need to check compressor mfgr data to determine factory oil type.

Chances are that the TEV inlet screen is plugged. remove, inspect, and replace if necessary, otherwise TEV element may require replacement (not likely).

I'd recommend oversized Sporlan "HH" drier. Apply suction drier if acid test indicates the need. Change driers again (after a few days) if deemed necessary by acid test results, or to make you feel better.

Recently I found a freezer whose TEV was restricted. The filter-drier had fallen apart, and the dessicant was plugging up the TEV inlet screnn.

good luck. :)

Thanks for your advice, herefishy. I'll have a go . What would you use nowadays instead of R11 to clean a system?

There is a product called CF-20, manufactured by Comstair Int'l, Inc. that is available here, in the USA, for that purpose. If you ask your wholesaler they may have this product, or some other alternative.

Driers REMOVE acid and waxes (the "HH" addresses the wax issue)"molecularly", whereas such contanimants are molecularly bonded to the drier media, and essentially "out of the system", so-to-speak. Sludge and varnish are also removed by the drier. The Sporlan "CW" series of driers advertises "alumina" removal. The CW line is designed for POE applications (extra moisture removal).

Have you determined the refrigerant to use, yet? If you are unsure about it, you may want to check compressor data to be sure your selection is appropriate.

You said the glass was dirty red? Sounds like someone may have put some of that DYE in there? The system that I had with the bad drier also had dye put into the system, by Johnny "can't find a leak" Jackleg!



see ya' :)

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You said the glass was dirty red? Sounds like someone may have put some of that DYE in there?

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Clear case of disposing the refrigerant and oil, and starting all over again :). If you cannot identify the refrigerant from the compressor model, herefishy's advice of using the TEV model number to identify the refrigerant is you next best bet.

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Originally posted by herefishy
You said the glass was dirty red? Sounds like someone may have put some of that DYE in there? The system that I had with the bad drier also had dye put into the system, by Johnny "can't find a leak" Jackleg!

see ya' :)

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Ah, Herefishy. I was just thinking about this disdain of yours the other day. My exact thought was: "I wonder what Herefishy would do in this situation." Let me explain.

We got our first heat wave a couple of weeks ago. It was a little late so it made up for the tardiness by being extra hot. Probably not by Texas standards, mind you, but for us wimps up here, it was warm.

I got an A/C service call about noon to a large convenience store over the eastern hills in the hot, dry flatlands. By the time I got there, I had two urgent refrigeration calls come in, so needed to get this one done ASAP.

The temp was only about 100°F and the store was a cool 90 but the owners were frantic. I climbed to the roof and found one smaller unit laboring away while the larger was short-cycling: one minute on, five off (TD relay). It was about 120°F on the roof, blistering sun: the kind of day you make sure to set tools in the shade or throw a rag over them so you don't burn yourself when you pick them up again.

I removed the panel and got my low-side gage on just before the unit cycled back on. Low charge. About this time I notice the unit behind me, a beverage case condensing unit, cycling as well, but with that straining noise compressors make that tells you it's going out on high head, not low pressure. I take a quick look and see only one fan turning. Great, another good excuse to stay up here and work on my tan!

I kill the power to both units, letting the beverage unit cool while I pull panels off the A/C and do a quick oil trace check. No oil, but return bends of the evap look suspicious. It's too bad the evap is behind the blower. I'll have to take the top of the unit off, including the exaust vent cowling, to get a really good look at it. I go down to get my detectors. On the way I check the beverage case. Sure enough, 55°F, but no one had noticed in the heat. Got my spray bottle and wet down my hat, hair and shirt. Brought up my electronic and my newest toy, a good-quality ultrasonic.

Disappointing, but even with plenty of pressure, not a whisper from the ultrasonic. Start going over it with the electronic, reaching in past the blower, trying to trace around the return bends when I get a couple of encouraging beeps. I start homing in, but now my electronic has decided it must have been mistaken, because regardless of sensitivity setting, it keeps quiet, peacefully humming away to itself without a care in the world.

So I looked at my choices: spend the better part of the afternoon in this hell disassembling, detecting, recovering, repairing, testing, evacuating, and reassembling while my customers, including this one, swelter and fret the day away. Or add the (shudder) ultraviolet dye, get this unit back in service, and come back in the cool of the evening (after the heat spell, judging from the lack of any significant leak) and find that sucker in five minutes with a flash of the old UV light. That's when I thought: "I wonder what Herefishy would do?"

Rog

OK
Recover all the refrigerant , change the oil, mostly your using mineral oil, change the drier, also use a large drier to help clean the system, install a suction filter dreir. ALso if it is a small system you may try supco 88 it dissolves any slug in the systme, this means you may have to go back and install another suction line drier. With the new oil install evacuate system total, recharge system.

ROG,

So what did you do. Don't keep us in suspense

I don't have much luck or faith in electronic leak detectors.

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Originally posted by RogGoetsch
I thought: "I wonder what Herefishy would do?"

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Rog, if it was my first visit to the equipment (or customer), and I went through the pains that you described, with no previous history, I would have recharged it and evaluated whether or not the low charge scenario re-occurred, and noted the timespan. Therby establishing a "history", and a little bit better basis to establish an appropriate diagnostic procedure.

I remember once going on some 10-ton package units, flatter than a door nail (no gas) and tearing my hair out (I don't have any), and then finding out that a disgruntled employee got on the roof and blew the charges on several units at several locations.

You never know what's going on, sometimes!! :)