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Post by dcraven on Oct 17, 2014 16:14:14 GMT
I recently got a non-working early 1950 GE Combination fridge off of craigslist. The model type is AH-83-AA16, serial number 04-450-950. I say it's non-working, the compressor runs loudly but it doesn't cool at all. There looks to be a tap already in one of the lines from from the compressor, at some point someone added coolant.   I've been trying to figure out what my options are. I have experience MIG, ARC welding, some electrical, plumbing & soldering joints. I've done some auto restorations including paint & bodywork but I don't have any experience working on sealed systems. I have repaired several modern fridges by doing simple fixes such as replacing the start relay switch, defrost heaters or other components and then reselling them cheap to fund my other hobbies. I called someone who seemed very knowledgeable and asked what it would take to get it working. He would charge $55 just to check the compressor, then $150 to check for leaks, a $100 for a more modern used R12 compressor (don't think that included installation) then using hot shot? as a coolant. It quickly came to $600-800 total and he was uncertain how reliable it would be. He did say the compressor could be noisy because it was low on coolant. Part of me would like to keep it as original as possible but that likely means higher cost involved. This would mean setting the fridge in a corner of the garage and waiting until I could afford it. With other projects that are a higher priority and bills this might mean it never happens. I have a friend who does professional air conditioning work and has all his own equipment. His suggestion was to find a donor fridge (lots on CL) that's using 134a to scavenge and build a franken fridge. The downside that he anticipated was a loss of 15% efficiency, the advantage would be the availability of 134a assuming it would work at all. I've read on some forums that it could cause a clog in the capillaries or wouldn't cool efficiently? I also thought of finding a donor R12 fridge to scavenge and asking if my friend would be able to charge it. If that was the case what refrigerant would be recommended and would you use the donor's condenser? Seems like that would make access to the back a lot easier. As is, the original condenser is part of the back of the fridge and makes things harder to get to. Another question is, there's a line coming out of the back near the freezer portion that I assume to be a manual thermometer that then goes to the thermostat. There are several kinks in the hard line and a break that you can see. Is my assumption correct that it's a Bourdon Tube type thermometer which won't work because it relies upon expanding gases to relay the temperature?   |
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Post by coldspaces on Oct 17, 2014 17:00:13 GMT
first step would be to hook to the line tap and see if there is any pressure in system at all. If not add trace gas and pressurize with nitrogen and check for leaks. also if you can post a video link of compressor runing it might help. If compessor is good I would find and repair leak and recharge with R12 or a R 12 subsitue.
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Post by jhigdon2 on Oct 17, 2014 17:17:58 GMT
Yup. 1 step at a time. Give it a complete physical. The Stat cap tube can be repaired too, if needed. I've found R409 to be a good R12 substitute.
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Post by blackhorse on Oct 17, 2014 18:14:18 GMT
I remember working on a few of these!
Notice the tag says "Primary refrigerant charge" and "Secondary refrigerant charge".
There are 2 sealed systems in this refrigerator, one powered by the compressor cools the freezer only. The second one is cooled by the first one and cools the refrigerator section only.
This was a brilliantly over-engineered design; the compressor cooled the freezer only, there was no thermal or air conduction between the freezer and refrigerator sections.
There was a "secondary" sealed system, with refrigerant tubes layed next to the primary cooling tubes in the freezer section, and a second set of evaporator tubes in the refrigerator.
There was a regulator in the lines of this secondary system between the refrigerator and freezer sections, controlled by the refrigerator cold control, a hand-operated wheel that turned the regulator up or down.
This compressor used some design features going back to the SO2 models, including that oil pressure was necessary to seal the piston in the cylinder; it was indeed noisy and developed no pressure if the oil migrated elsewhere due to a leak or low charge.
I would try first of all, to discover just how deep in you are, evacuating and recharging the primary system with a R-12 substitute refrigerant. If a full charge displaces the oil back to the compressor and you get cooling in the freezer, you basically need to look for the leak and fix it. Keep in mind the most common leaks I find are at tap valves that someone has installed because they thought it needed a charge, forgot to close properly, left the cap off,...... >.<
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Post by dcraven on Oct 17, 2014 19:15:27 GMT
Great information, not only for myself but someone else I'm sure will benefit from having this information online! I did happen to pickup at lunch a free R-12 donor in case it's needed that I can take the compressor & condenser off of. And at least if I go the route of having a professional do everything I'll be able to comprehend more of what's being done. It also confirms what the first technician was telling me, about how if it wasn't charged it would be noisy. The 2nd tech just said it meant the compressor was bad. I did find something useful at hvac-talk.com/vbb/showthread.php?1295781-1950-s-refrigerator-problem"Its a GE, the model # is an ah-83-aa16, ser # is h3133-549. its an r12 system and there are 2 different circuits,but with only 1 compressor. so the discharge line runs through the whole back panel that acts as the condenser, then it cap tubes up into the freezer section, its metered there and flashes off through all that aluminum tubing which wraps around the whole freezer section,then the suction line comes off the freezer box,goes into this manifold,comes out(so really all it does is pass through),then goes back to the compressor. now when I pressure tested,evacuated and charged through my new port on the suction line just a few inches from the compressor, in no way was the refer section effected as far as pressures go. the 2 other lines that go in and out of that manifold are separate circuits. so heres what iv done since I posted...the 2 lines that run through that manifold and down through the refer section is where i added another one of my own ports, pressure tested and evacuated,then charged with the secondary refrigerant weight and turned the thing on. now the refer section works and is at 36*. I completely understand how refrigeration works as im a journeyman mechanic, but I just cant seem to figure out what that part is, and why and how it works. and how does the refer section get cold if it doesn't have a compressor, or tied in with the refer circuit? I thought maybe its a heat exchanger of some sort? im at a loss...but good news is...IS THE DAMN THING IS RUNNING! I guess you can say I fixed it, just doing what I thought would work. Ok, after dusting off some of my old refer book collection, I found your GE circuit. What you have is common for other domestic units of the time period. Basically, what looks like a manifold, is called a "Header". The circuit works as follows: Compressor pumps high psi vapor into the condenser, then the liquid passes thru a cap tube, which is tied to the suction line return, for heat exchange. Then, onto the first of your 2 evaporators, which is the freezer first, and then thru the header, and onto the fresh food evaporator, and then home to the compressor. It is all tied in together in series, so you must of been undercharged, had a restriction, or did not allow enough time for the fresh food compartment to get cool last night." The book that the explanation came out of was ""AUDELS REFRIGERATION and AIR CONDITIONING GUIDE" Copyright 1944 thru 1959, page 235." |
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Post by coldspaces on Oct 18, 2014 21:56:56 GMT
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Post by blackhorse on Oct 19, 2014 19:50:33 GMT
Great information, not only for myself but someone else I'm sure will benefit from having this information online! I did happen to pickup at lunch a free R-12 donor in case it's needed that I can take the compressor & condenser off of. And at least if I go the route of having a professional do everything I'll be able to comprehend more of what's being done. It also confirms what the first technician was telling me, about how if it wasn't charged it would be noisy. The 2nd tech just said it meant the compressor was bad. I did find something useful at hvac-talk.com/vbb/showthread.php?1295781-1950-s-refrigerator-problem"Its a GE, the model # is an ah-83-aa16, ser # is h3133-549. its an r12 system and there are 2 different circuits,but with only 1 compressor. so the discharge line runs through the whole back panel that acts as the condenser, then it cap tubes up into the freezer section, its metered there and flashes off through all that aluminum tubing which wraps around the whole freezer section,then the suction line comes off the freezer box,goes into this manifold,comes out(so really all it does is pass through),then goes back to the compressor. now when I pressure tested,evacuated and charged through my new port on the suction line just a few inches from the compressor, in no way was the refer section effected as far as pressures go. the 2 other lines that go in and out of that manifold are separate circuits. so heres what iv done since I posted...the 2 lines that run through that manifold and down through the refer section is where i added another one of my own ports, pressure tested and evacuated,then charged with the secondary refrigerant weight and turned the thing on. now the refer section works and is at 36*. I completely understand how refrigeration works as im a journeyman mechanic, but I just cant seem to figure out what that part is, and why and how it works. and how does the refer section get cold if it doesn't have a compressor, or tied in with the refer circuit? I thought maybe its a heat exchanger of some sort? im at a loss...but good news is...IS THE DAMN THING IS RUNNING! I guess you can say I fixed it, just doing what I thought would work. Ok, after dusting off some of my old refer book collection, I found your GE circuit. What you have is common for other domestic units of the time period. Basically, what looks like a manifold, is called a "Header". The circuit works as follows: Compressor pumps high psi vapor into the condenser, then the liquid passes thru a cap tube, which is tied to the suction line return, for heat exchange. Then, onto the first of your 2 evaporators, which is the freezer first, and then thru the header, and onto the fresh food evaporator, and then home to the compressor. It is all tied in together in series, so you must of been undercharged, had a restriction, or did not allow enough time for the fresh food compartment to get cool last night." The book that the explanation came out of was ""AUDELS REFRIGERATION and AIR CONDITIONING GUIDE" Copyright 1944 thru 1959, page 235." The first paragraph (the guy's personal experience) is a fair description of what he saw, but (by his own admission) not strong on theory. The "part" is not a manifold, though it might appear so by the number of tubes connected to it. 2 of the tubes go to the loop in the freezer section. The other 2 go to the loop in the refrigerator section. The device regulates the flow between the loops, and thus the cooling in the refrigerator section. (Pictures attached) The yellow marks are factory. The secondary system has it's own unit tag. The 5th (smaller) tube has a service/process fitting with a plastic seal over it; it takes a tool with the same spline as the monitor top units. The part has an obvious seam in the middle. The silver half is not gas tight, and even has several holes to keep it at atmospheric pressure. It contains a spring, and the "T" shaped shaft sticking sideways out of the center post varies the tension on the spring, by means of the "warmer/colder" control in the box. The black half is welded closed and contains a bellows under refrigerant pressure (which varies with temperature). I have not cut a bellows open, but it appears to have a needle that seats in the center tube of the device. So when the refrigerator warms, the pressure in the bellows opens the needle and allows more refrigerant from the freezer loop to flow through the refrigerator loop; when it cools the refrigerator section the needle closes. The temperature that this occurs is set by the balance point between refrigerant pressure/temperature, and the tension on the spring (adjusted by the "colder/warmer" control). Quite an effective system, as the refrigerator section can be cooled by the cold in the freezer, even when the compressor is not running. The compressor comes on to cool the freezer, and can do so without cooling the refrigerator if it doesn't need it. The temperature of each section is maintained at it's control set point separately from the other, regardless of differences in loading. The second paragraph does NOT describe your machine, though if you disregard the reference to a "header" it describes almost all other 2-door refrigerators that don't use an evaporator fan (forced air cooling inside the box). They commonly have a larger evaporator in the freezer and a smaller one in the refrigerator section, in series (one after the other in one refrigerant loop). There is a brief mention in the first paragraph that seems to imply that the condenser is inside the cabinet walls. If this is the case with your unit, that is a very common place for refrigerant leaks to occur. It's almost always steel tubing, spot-welded to the inside of the steel cabinet wall. It rusts through over time, especially if the unit sits unused for a while. This is one of the simplest leak repairs there is. Completely abandon the condenser inside the cabinet walls, and simply hang an external condenser coil on the back of the cabinet, attach the compressor discharge line to the top of it and a filter-drier to the bottom, and your cap tube to the dryer. Use a coil from a refrigerator with the same Hp compressor as yours (1/4 Hp I believe). |
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Post by dcraven on Oct 30, 2014 3:03:59 GMT
I had a service tech take a look today at the fridge. He did exactly as all of you suggested, testing it for pressure and then using nitrogen to check for leaks. Unfortunately it turned out to be leaking somewhere around the freezer box inside the walls. We didn't hear any hissing until he opened the freezer door, but neither of us could find any holes in the freezer box itself that might explain what had happened, ie. ice pick damage. At that point he said there wasn't anymore that he could do. One good thing out of this, I was expecting a $55 service fee plus additional costs for the nitrogen & leak detection. Instead he only charged $40 total.
He did say the compressor sounded fine, but the thermostat has problems. The line has 3 kinks in it with one visible crack that I could see. Is that pretty much it then? I've been making a list of things to do with a broken fridge which includes an electric smoker though not sure how that'd work with 2 compartments. Seems like someone out there might be able to use some of the parts of it.
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Post by coldspaces on Oct 30, 2014 3:12:40 GMT
Wow sounds like it would take some real work to disassemble it to get to what is leaking. Shame to see a dual sealed system unit die.
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Post by dcraven on Oct 30, 2014 3:53:39 GMT
This is a 1923 Gulbransen player piano I've been restoring. This weekend was the first time it's been in tune and playable for who knows how many years. So many of them are sent to the dump or burned. When I got it only 2 keys played, so bad that not only did I get it for free but the owner paid all moving costs. I knew nothing about pianos at the time. It's taken a lot of patience, still needs work but the sense of pride makes it worthwhile. www.pianoworld.com/forum/ubbthreads.php/topics/2272803/Reconditioning_1923_Gulbransen.html#Post2272803It's possible to do then, assuming there's no rush and you take your time? I'd much rather have it work as a fridge than turn it into a smoker. For now I could use it for storage until I've completed other ongoing projects. Could be a year or two but that's better than never. |
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Post by blackhorse on Oct 30, 2014 3:55:42 GMT
I would think with a sound to narrow it down, a spray bottle of soapy water would be able to isolate the leak.
As I recall, the back of the cabinet comes off to expose the back of the freezer box.
Even if the exact leak is impossible to get to (up against the sheet metal?) a bit of new tubing could be spliced in. I think it was all tinned copper tubing.
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Post by dcraven on Oct 31, 2014 13:53:03 GMT
I wish I'd thought of removing the back access panel when the service tech was here. Unless someone stabbed the freezer walls with an ice pick (which we both couldn't find evidence of), to me it seems the likely spot for a leak would be in the back because maybe something happened when it was either being serviced or messed with. Typically you wouldn't expect to find leaks on the sides of the freezer box would you?
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Post by blackhorse on Oct 31, 2014 16:30:12 GMT
OH bloody hell, leaks can be anywhere. With air conditioning I've found leaks in the ceiling where a game of darts went horribly wrong. Particularly with something with an unknown history you never know what's been done in the past that makes no sense now (maybe didn't even then). A long sheet metal screw being reassembled where a short one was supposed to go. Cleaning with oven cleaner or bleach where a mild detergent was called for. Using boiling water to defrost.
But I don't recall even seeing tubing around the sides of the freezer box, most of the tubing was on the back, which served as a heat exchanger with the secondary system, with the tubes of both systems interlaced for heat transfer. I'd certainly take the back off and then listen for the sound, and apply soapy water where it seems to be coming from.
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Post by dcraven on Oct 31, 2014 17:38:30 GMT
I'll try to take a look this weekend, problem is borrowing or getting a setup that allows me to do the leak testing myself. Autopart stores sell a 134a gauge setup, if I could get a nitrogen tank would that work for testing or does it have to be an R12 rig? I have an argon tank used for MIG welding, as well as scuba tanks. Does the inert gas used have to be nitrogen? Can you get a small can of nitrogen like you would 134a when charging? I apologize for such basic questions. If you know of any websites that offer guidance or alternatives please let me know!
If I can get the leaks fixed myself then I would call the service tech out to do the R12 charge. That would be a MAJOR hurdle!
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Post by blackhorse on Oct 31, 2014 20:32:49 GMT
I'll try to take a look this weekend, problem is borrowing or getting a setup that allows me to do the leak testing myself. Autopart stores sell a 134a gauge setup, if I could get a nitrogen tank would that work for testing or does it have to be an R12 rig? I have an argon tank used for MIG welding, as well as scuba tanks. Does the inert gas used have to be nitrogen? Can you get a small can of nitrogen like you would 134a when charging? I apologize for such basic questions. If you know of any websites that offer guidance or alternatives please let me know! If I can get the leaks fixed myself then I would call the service tech out to do the R12 charge. That would be a MAJOR hurdle! Other dry, oxygen free, nonflammable gasses will work, but 1) be sure to use the manifold gauge set, so you can monitor pressure. 2) be sure to use a regulator for any high pressure gas (in excess of 200 PSI, I'd say). If you get a 134a rig from the auto parts store it will have an Acme Thread hose on it to fit cars, and will not fit the SAE 1/4 Flare fittings that are universal for stationary equipment. You may be able to cheat by getting another hose for the set. Or get a regular gauge set. They have cheap ones at at Harbor Freight, though the quality is less than stellar. In any event the tank will have to be fitted with a male 1/4 Flare fitting to take the hose. Whenever you solder any closed system you have to have some fitting open somewhere, low side for low side work, high side for high side work, for safety as well as because any pressure in the system will keep the solder from sealing the joint properly. |
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