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Post by andrewk on Jan 10, 2017 23:35:43 GMT
As I discussed in the heater thread , this past month my CA-1-B16 had developed a rattle which i had figured was due to a bad heater especially since the frost line began to drop as the nights got progressively colder and colder. After a few nights of close to freezing temperatures, I defrosted the machine because of a ton of ice buildup from previous months and replaced the heater with a 15w pipe heater coiled tightly and pressed into a .270 win brass casing with the necked down part cut off (essentially a just under 1/2" diameter brass tube), and after 12 hours of letting it heat, the rattle was still there but now it just wasn't cooling. I had this happen once before a bit over a year ago after I rewired the unit and I recall using a rubber mallet to smack the float housing which got the fridge working again. I did this again as well as play around with a very strong rare earth magnet on the housing and for a short period of time, the tube (when looking into the fridge from the open door) coming from the left of the float chamber, was ice cold, and so was the rear of the evaporator. From the research ive done, it seems like its caused by one (or more) of three things. 1. Float valve sticking 2. Blockage in evaporator caused by methyl formate condensing and sitting below the oil which wasn't being heated properly. 3. Lack of refrigerant (caused by leak? even though it ran find for the past year? and previous 80 years?) here is a video i just took of the refrigerator so you guys can hear the rattle, and how i was thrown a curveball because the unit seemed to be cooling even though it didn't cool at all previously. /confused |
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Post by andrewk on Jan 11, 2017 2:29:20 GMT
Just a quick update. It's working now. lol. I just went out to the garage expecting the overload to be tripped and it was rattling much less, the temp reading inside the evaporator was 21'f, left tank was frosted to the top and the right was frosted about 10% up from the bottom. I then felt the condenser and the top was much warmer than the bottom, and the dome of the unit was pretty warm as well. It's also cycling on and off though i haven't timed it. So could all this have been due to a bad heater? And that it just took a long time to heat the methyl formate out of the oil? At 12 hours after heater install, no cooling. At 24 hours i got the trickle of cooling, and now at probably 36 hours, its working again. Temperature last night was probably in the high 40's in my garage and during the day it probably was around 60'f outside. a bit warmer inside since i heated the garage up with my propane heater.
Now that it's running, i'm sure NCG's are a factor in the temperature differences from top to bottom of the condenser, so that being the case, how long should i let things run before putting a pan of hot water in the evaporator and go through the process of bleeding the system? also, if you have some insight into the causes of this i'd appreciate it.
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Post by elec573 on Jan 11, 2017 4:58:42 GMT
HI Andrewk !
Welcom to the forum !
Ok trouble shooting 101 make sure of what you have !
1 If you suspect a leak (don' t no why you would unless someone went in with a pick ax ) use soapy water on all joints look for bubbles !
2. Check heater maker sure it is working and leave on long enough time 8 hours I recommend at least !
3. Next check and bleed if necessary non condensable gases ! ( cablehack has an excellent video on this )
4. If all of that is ok then we can check into float sticking and other things !
Chris & cablehack are the resident experts on cas I'm sure they we'll be happy to help !
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Post by andrewk on Jan 11, 2017 6:32:23 GMT
HI Andrewk ! Welcom to the forum ! Ok trouble shooting 101 make sure of what you have ! 1 If you suspect a leak (don' t no why you would unless someone went in with a pick ax ) use soapy water on all joints look for bubbles ! 2. Check heater maker sure it is working and leave on long enough time 8 hours I recommend at least ! 3. Next check and bleed if necessary non condensable gases ! ( cablehack has an excellent video on this ) 4. If all of that is ok then we can check into float sticking and other things ! Chris & cablehack are the resident experts on cas I'm sure they we'll be happy to help ! hmm.. welcome to the forum? /confused I'm not new, but returning after a year or so dealing with life's complications. In fact, i wouldn't be wrong in saying It's good to see such helpful new members such as yourself!  As for the 101, i've been through all that already. Leak is clearly not the issue because it started working again. The heater works perfectly because its brand new and the kill-a-watt says 14.9w. I'm sure it needs bleeding but NCG's aren't the reason why the thing wasn't cooling any. The compressor runs great and i either had a blockage that happened after my previous heater failed or the float valve got stuck... or something. Tomorrow ill probably heat it up a bunch and bleed it and see how its running. If it does this again, ill likely do a capillary conversion to take that float valve out of the equation. And i'm sure Chris and Cablehack will set me in the right direction as they have many times in the past. They are definitely two of the most knowledgeable people i've come across on these machines. |
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Post by elec573 on Jan 11, 2017 7:03:00 GMT
Well welcome back either way don't know every body on this forum but I think we all have one thing in common we love these machines !!!
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Post by ckfan on Jan 11, 2017 15:04:45 GMT
Just a quick update. It's working now. lol. I just went out to the garage expecting the overload to be tripped and it was rattling much less, the temp reading inside the evaporator was 21'f, left tank was frosted to the top and the right was frosted about 10% up from the bottom. I then felt the condenser and the top was much warmer than the bottom, and the dome of the unit was pretty warm as well. It's also cycling on and off though i haven't timed it. So could all this have been due to a bad heater? And that it just took a long time to heat the methyl formate out of the oil? At 12 hours after heater install, no cooling. At 24 hours i got the trickle of cooling, and now at probably 36 hours, its working again. Temperature last night was probably in the high 40's in my garage and during the day it probably was around 60'f outside. a bit warmer inside since i heated the garage up with my propane heater. Now that it's running, i'm sure NCG's are a factor in the temperature differences from top to bottom of the condenser, so that being the case, how long should i let things run before putting a pan of hot water in the evaporator and go through the process of bleeding the system? also, if you have some insight into the causes of this i'd appreciate it. "Now that it's running, I'm sure NCG's are a factor in the temperature differences from top to bottom of the condenser". That right there tells me a lot. When you have NCG's in the system you WILL notice a large difference between the top and bottom of the condenser, especially when it is under a heavy load. I have noticed however that when under a light "normal" load, you will notice a slight difference in temperature from the top to the bottom of the condenser even when the system has been properly bled and or isn't having any issues. Also!, the fact that you have the machine in an unconditioned space has A LOT to do with erratic performance when NCG's are in the system. Look at the clip that I took out of the CA manual, it tells it better than I ever could. Temperature swings in the room that the CA is in will have a large effect on how it performs when the system is full of NCGs. It all has to do with the NCGs pressing on the float valve. When the room temperature is low, the internal pressures are lower and the refrigerant can't overcome the opposite force that the NCGs are putting on the float valve. Raise the room temperature a bit and an equilibrium is achieved and the machine may start to operate right again. This leads me to believe that you have a MILD case of NCG buildup. My machine was so bad that it would barely refrigerate at all, even in a warm room. Did I mention how gosh darn weird these machines are!? That is why I love them.
So, I would look up the video that Cablehack did on how to bleed your machine. It is super easy if you have the bristol key and will make a world of difference. Don't be surprised if it takes you a long time to bleed all of them out. Just make sure to smell the gasses coming out every once in a while to make sure you aren't bleeding off the refrigerant. You will know when you smell the refrigerant. Since your machine is a form B machine it will build up much more NCGs before an issue develops. Good for reliability, frustrating when it comes time to bleed. I would assume that there is nothing seriously wrong with your float valve since it is working so well otherwise. However, I would stress to you the importance of keeping an eye on your machine and don't let it run for too long with an excess of NCGs in the system. There is enough evidence for suspicion, not proof, that the NCG gasses that press down on the float cause erosion of the float seat as the liquid refrigerant tries to creep past the needle. So in other words, your machine is working great except for one thing, you can keep it working that way if you perform this "regular maintenance" when necessary. Of course you won't really know it is necessary until you see the frost line start to drop or have erratic refrigeration like you are having now.
Sorry for the long winded response but I wanted to cover all the bases. I can tell you love this machine and you did the right thing by replacing the heater with your macgyver'd solution (which I totally like). Now (it would seem) that you are just a bleed away from being able to enjoy your CA again. Of course I could be completely wrong, you never know with a machine this old.
Let us know if you have any more questions. Oh, and take some more pictures of this beauty when and if you get it working right again. It looks great from what I can tell!
Edit: I just read through your previous posts and saw it put together. Wow, you do very good work. You are much more patient than I am. Very great attention to detail. Since you have already bled this fridge twice it is a little odd that you would need to bleed it again but it is not unheard of. When I got my CA it didn't really act right until I bled it 3 times. Since you smelled MF the last time you bled you did the right thing by stopping however. I would carefully bleed it again making sure to not catch a whiff of that sweet smelling MF. Hopefully it just needs to be bled again, good luck and let us know what you find out!
To view the photos in this post, please follow this link: drive.google.com/open?id=0B8_jm7K-ahMaYWxWVVY2OEtiTUE
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Post by ckfan on Jan 11, 2017 15:29:46 GMT
BTW Andrew,
I just read your previous posts on this machine and I am impressed. The fact that it was running for most of its history is good to know. That tells me that every once in a while, you will find a CA that has had a history that is trouble free. That is refreshing. Heck, for any refrigerator to do that is very impressive. The fact that it was your grandmother's fridge just makes it more sweet. Looks like you did a great job of getting it painted. I hope that a simple bleed is all it needs to continue to carry on your memories of your grandmother. Very cool.
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Post by ChrisJ on Jan 12, 2017 2:56:20 GMT
Cablehack has worked on these more, but since you said it had been working, my first step would be to carefully tip it forward on the front two legs an inch or so, and then drop it back on the rear legs. Make sure you don't risk it tipping backwards or anything, but you want to give the float valve a shock. If it's stuck, this may work. Make sure your feet are clear of the legs when you drop it.
To me, it sounds like there's no refrigerant in the evaporator, or very little. The amount of time yours was running in the video, that evaporator should've dropped substantially.
If dropping it like this a few times has no effect, I would put some oil in the charge valve and slowly crack it and see if you get outward pressure. If you do, perhaps NCG is your problem.
Soap testing for a leak isn't going to work because most of the system is in a vacuum.
I would do the tip \ dropping with it running, and it must be running for the NCG bleeding.
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Post by cablehack on Jan 12, 2017 5:44:00 GMT
NCG can actually stop refrigeration altogether when it builds up enough to make the float valve inoperative. The GE film excerpt mentions this, and back in the day when I did have an operating float valve I did see it happen this way, at least once.
Cap tube fitted machines can run a lot longer with NCG's. For instance, my CA-2 only gets twitchy when only half the condenser is active and the room temp gets above about 25C. Even then it's not yet rattling, but it runs out of cooling capacity. The dome also runs hotter in this situation, because it being on the high side it is trying to act as a defacto condenser.
In fact, I had to purge it a few weeks ago because the hot summer weather was too much and it stopped cycling, tripping my 30 min compressor timer. It had not been purged for about seven months, which for this particular fridge is excellent going. Having done the purge, it takes 30C room temps in its stride without any stress.
As ckfan has pointed out, room temperature swings have a large effect on these machines. Not in a bad way, but just how they work. For instance, a drop in room temperature over a day or so might cause a rattle. One may immediately think the machine needs to be purged, but on further thought it is realised there has been a temperature drop, and sure enough once the temperature has stabilised, the rattle is gone in another day or so.
Another thing with frequency of NCG purging is the time between purges can be quite variable and fluctuate. As an example, my CA-1 ran for 18 months before it needed a purge. The next purge was needed only a few months after that, but since then it's gone for another 18 months and there's still no sign of needing a purge.
One other thing that I have seen stop the cooling is what appears to be an oil slug building up in the evaporator. Stopping the compressor, allowing the evaporator to come up to room temperature, and restarting seems to be a reliable way to deal with it. The higher pressure then (if you can call 10psi high pressure) forces the oil back into the compressor; well that's just my theory. I've observed this effect with both CA-2 evaporators, but only once with the 'new' one shortly after the transplant. Never seen it happen with the CA-1.
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Post by elec573 on Jan 13, 2017 5:27:05 GMT
Question is there a know cause of NCGs ?
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Post by ckfan on Jan 13, 2017 14:24:46 GMT
Question is there a know cause of NCGs ? I know that any amount of moisture in the system will cause them. Apparently they can also be created by heat as well but I am not certain about the specifics of it all or the chemistry behind it. |
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Post by ChrisJ on Jan 13, 2017 20:21:01 GMT
Question is there a know cause of NCGs ? My understanding is methyl formate breaks down into NCG as well as formic acid when it comes in contact with moisture. Not sure how long this takes. Also, temperature causes it, though I think it breaks it down slightly different. The way it was explained to me was, it'll break down at one temperature over a long period of time, or faster at a higher temperature. The hotter you get it, the faster it breaks down. I believe this does not happen below a certain temperature but I was never able to find what that was. My assumption has been CA machines that were never really worked hard in extreme temperatures may have never had a NCG past their initial one due to moisture left in the system. Others, working in high temperatures, 90-100F+ making a lot of ice, likely developed a lot more NCG. We also assume using a machine for a prolonged amount of time with enough NCG to keep the float from fully opening is what destroyed a lot of valve seats and needles. Holding the valve partially open would in theory cause flash gas in the valve and erode it. |
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