Frigidaire D-4 belt drive maintenance w/o losing SO2 charge?

Ok, some pretty unexpected stuff happened after the last test. Me being tired from the bad result, I just walked away from it all and left the valves closed with the vacuum still in the compressor. To my surprise when I returned two days later, it had now reached a small positive pressure! This could only mean one thing. I didn't shut the valves tight enough! Ok then! I opened them both up and let it run for a cycle before once again, the 4th time, performing the vacuum test. For some reason it took some time now to reach about 20" Hg of vacuum, like at least 30 seconds (as compared to only a few revolutions earlier). But once there I turned it off and quickly shut the discharge valve.

There was some visible rise in pressure during the first minutes, and just as I was getting up to go away for a while I heard a little *poof* sound. Umm...what? In just a second, and with the valves now firmly shut, it was up to like 15 psi?! At first I thought, vad i helvete? This is just too damn weird. HOW can that be? Am I dreaming some surreal dream here or something? It shouldn't be possible! After thinking about it for a while, the only theory I could come up with was that in a pocket somewhere, maybe in the line to the gauge or the line to the sylphon in the switch, it must have had liquid SO2 held in it by capillary force. Then in the vacuum slowly beginning to boil off at the top until all of it left was suddenly released in an instant, creating this pressure. Either that or a strange pocket of liquid SO2 under the compressor oil? Anyway, I opened up the discharge valve a little bit and again ran the pressure down to 20" Hg. There was also this time some pressure rise during the first hour, but then it settled at 13" Hg and stayed there! That's by far the best reading I got to this date while performing these beginner vacuum tests.

With that said, there are some things I failed to mention when I wrote the post after test #3. As I said, I purged the air by loosening the flare at the discharge valve before the test. However, the service manual is clear on the fact that you have to purge the air very carefully, to not disturb the SO2 vapor underneath it. When I loosened the flare, I had to apply a LOT of force, before it would let go with a SNAP. (It appears as being completely untouched possibly all the time since first being mounted there in the 1920's.) This snap made the compressor shake wildly up and down in the suspension! But I carried on anyway and loosened the flare just so much I could hear it seep and purged the air. Then I performed the failed test #3 and when realising I didn't shut the valves tight enough I decided, ok I'll just start it up now that I purged the air and let it run and see what happens with the knocking sound. The sound was back after a day of running. Ok, so now in this mess we're back at just before start of test #4 when I also realise I probably didn't purge the air well enough the first time. I'll just do it again, since now the flare will let go much easier (even though I had to tighten it down pretty hard to make it stop leaking, as indicated by the handy little check with ammonia the manual says to perform). So again I purged the air. I let it seep until the other handy little indicator set off (the one you know is buzzing when you stop being able to breathe 😅). After that I performed the more successful vacuum test #4. Having seen the result of that I decided to power the fridge back up again and continue examining the knocking occurance.

That was three days ago. It has now been up and running since then and the knocking sound has so far not returned!

Now I did say I was going to get the compressor out. But apparantly there's still some slight chance I might not have to take this system apart. Or at least not the compressor. If that comes true, it's just unbelievable. But right now we have to wait some more and see how this will evolve before we can tell for sure. (And sure I want to be before doing anything with it.)

Sorry for long text again



Regards
Sasha

You could produce SO2 by burning sulfer, but collecting the gas and purifying and dehydrating may prove difficult.
I have seen what I believe may be the easiest, most economical way to produce SO2 is a method by which gold refiners bubble sulfer dioxide through chloroauric acid to precipitate the gold from solution, it is a simple procedure.
In a flask make a slurry of sodium metabisulfite and water. Arrange a stopper and delivery tube such that sulfuric acid may be introduced to the slurry at a controlled rate. The sulfuric acid reacts with the sodium metabisulfite to produce sulfer dioxide. Route the delivery tube to another stoppered flask as to bubble the SO2 through sulfuric acid to scrub the gas. This is high purity SO2, but it would be good to insure its dryness, possibly by passing it through a drier containing silica gel (silicon dioxide).

Hey David! I watched one of your videos before where you replaced the electrical motors rubber mount bushings with that from a GM cars sway bar (don't remember which make or model). However, while the bushings on this compressor unit are in like new condition...







...there's another bushing which is for some strange reason now crumbling away:

The belt tensioner mount bushing. (WHAT'S THIS! It's not even been 100 years!)


I was just wondering if you encountered this and if so, how did you rebuild/replace it?

The pin in the middle on which the spring runs was about to come loose on mine. Now that I am performing endurance tests and having to run the unit for days on end I figured this have to be taken care of immediately, so it won't let go completely and cause a disaster!


I came up with this quick solution:

Another spring that simply pulls the pin itself down in place!


This will keep it there in place for now. And it did greatly reduce swaying in the motor and belt. But eventually a permanent solution will be needed.
Hence this humble question of mine for you, while I'm at it anyway flooding the thread with more new pictures. 😊


And for a progress update. The unit is still up and running. It has now been going for a full week and the compressor is going strong. There have been some minor intermittent knockings the whole time (as compared to knocking 100% of the running time earlier, once it did start to knock), but it does not seem to be getting any worse. I think there might be a small pocket of air remaining inside, possibly drawn in during the last vacuum test a week ago.



Regards
Sasha

You could always drain some old car batteries I suppose. If it's not an issue with having some lead contamination in the sulfuric acid in this process?


When researching yesterday about what you said I came across this video below, on youtube
I thought it'd be interesting to see, but I'm not sure whether this method would be easier or harder than the one suggested by you




He melts and burns sulfur in a burning dish under an inverted funnel
routes the SO2 gas via a makeshift drier consisting of two cotton pads with calcium chloride in between them, encased in a big syringe
the gas will then go into a test tube placed in a dry ice aceton bath where it will condense into liquid state, led there by means of aspirator pump
after that the test tube is replaced by another empty tube in the cold bath and then connected to the first tube with the unpure SO2 in it
the SO2 is then transferred from the first tube to the new one by simply letting it vaporize itself, leaving the impurities behind.

The question here is of course how pure the purified SO2 will actually be, given that the sulfur wasn't burned in oxygen, but in ordinary air (which we know is a mixture of gases). Any takes on that?


Regards
Sasha

I might have a little update in the making, intended on coming soon.

Before getting to that I want to bring this up:



The electrical motor!


From what I read in the service manual the F compressor has a 1/5 Hp motor. On 220V that one will draw a current of 3A.
But why do I need to look in the manual for some basic specs like that?

The reason is simple:




It's ID-plate is disappeared!

This leads me to believe that in the past there has been an event with the motor where they needed to get it out for repairs and something happened in the handling of the motor that made the tag accidentally come off. Either that or someone intentionally removed it for some bizarre reason. I can't see how this riveted plate could fall off by itself when the motor is sitting in place well shielded in the compressor apartment. For precaution I have shined a light under the suspended compressor rack also and from what I can see it's not laying there either.


I'm looking for answers to some questions regarding this. The main ones are these:

1. Is this still the 1/5 Hp motor?
2. A potential repair may have been on those a little infamous centrifugal weights. How to know if it have the good ones or the bad ones?
3. Since this motors internals are untouched for many many decades, in what condition can we expect the oil wicks to be?
4. From what I can remember from rewireing in 2017, there's no overload protection present at all. Best way to solve this?

I hope I'm not overloading you with questions now...




Edit
Now that I think about it, I don't know the nature of those ID-plates. If they are maybe thin and stands the chance of possibly being accidentally teared off for some reason when for example maintenance work on the compressor unit is being performed by a serviceman.





Regards
Sasha

Thanks David for great replies!


I did some photograhing today through the front ventilation of the motor but the weights appeared a lot more dusty on the photos than IRL, to the point of seeing the actual surface on them became difficult. I have to try and get the dust off and give it another go. So I'll get back to you on that one. (When doing that I could also hook up a multimeter and measure the amps which I forgot about.)

A big reason why I started worrying about the oil wicks was that when I first powered the unit up earlier this year I added some oil (like a teaspoon in each lubrication tube). But some week later I discovered that some amount of it just flowed right through and down into the bottom of the housing and then further down out on the outside of the motor. 

When it comes to the protection, "Klixon" was like what I had in mind. I read about it earlier in your posts but couldn't remember just the term or where it was mentioned. I did some initial searching now and got some results, but there was little to no specs provided. I wouldn't mind having one of those neat original ones that seem to be common (at least in the USA) on Frigidaires, with the reset button. Though I don't know if that will be feasible. If not, I'm ok with settling for a Klixon type breaker. As of my findings today, there's indeed no protection installed.



Here's a pic I took today from inside of the little electrical box underneath the control unit. I'm not sure if the blank cover plate (as seen in earlier posted photos) is original. It can't be ruled out that it was actually put there later on. There is a trace of something behind it, a round piece that two wires is going through. I didn't get what that piece was for back in 2017. But I let everything be the way it was when I did the rewiring, so the old wires will have been placed the same way.




(I unscrewed the black plastic covering on the right connector only so that you could see how it looks like underneath them.)



Some follow up questions:

1. Did I maybe overoil the motor?
2. The Allen-Bradley overload breaker, is that the one with the reset button? (Only available in USA?)
3. From the photo above. You got any idea of what the round thing with cables going through it might have to do with?

Regards
Sasha