wiring questions: 40's fridge ( Did I mess things up?) - Page 2
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  1. #14
    Join Date
    Sep 2002
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    2,704
    Hold off on it, we are going back to Sulfur dioxide,may find a compressor for it.

  2. #15
    Quote Originally Posted by coolperfect View Post
    Hold off on it, we are going back to Sulfur dioxide,may find a compressor for it.
    I did some more reading and one thing that was on this site was the mention of using MP39 as a replacement refrigerant after the system got a nitrogen purge. Apparently I'm going to need to do a lot of research before coming to a conclusion on this one.

  3. #16
    I did some more research. It would be impossible to re-use any of the old system in this as it works totally differently from a modern system. The innards are also permanently contaminated with oil and that will ruin any new compressor.

    So I have one option it seems. It will be a lot of work but not impossible. It would consist of removing the old condenser and disconnecting the original evaporator. I would then need to either find a donor fridge or find either used or NOS parts online, install the replacement modern condenser on the back, install a new evaporator up top and install a new condenser in place of the old. The fridge totally comes apart and the top comes off allowing you to get at all of the components. Seems like people give away 80's and 90's fridges around here all the time, so the costs to do this might be inexpensive but again- time consuming.

  4. #17
    Join Date
    Jan 2010
    Posts
    5,956
    Quote Originally Posted by icemeister View Post
    Units from that era typically used a "hot wire relay" as the primary starting component for the compressor. It's purpose was twofold. One to de-energize the start winding when the compressor comes up to speed and also to protect it from an overload condition.

    I suspect that's what once was in that junction box.
    Hi icemeister !
    Do you have any more info on that electric setup ?
    TIA,
    VTP

  5. #18
    Join Date
    Jan 2010
    Posts
    5,956
    [QUOTE=bobwilson1977;15246231] I tested the resistance and there's basically none on the starter coil.

    What is "basically none" and how did you test it ?

  6. #19
    [QUOTE=VTP99;15261641]
    Quote Originally Posted by bobwilson1977 View Post
    I tested the resistance and there's basically none on the starter coil.

    What is "basically none" and how did you test it ?
    There are 3 wires that lead to the compressor: 1 black, 1 white, 1 green. I tested combinations of the three and only get resistance between green and white but nothing else. There should be two leads that have a smaller amount of resistance with the primary coil showing the most. As a last resort I also connected the black and white, then combinations of black white and green to 110 volts. Nothing. The unit had been working before. Then it stopped. So I assume the starter coil fried. Again- my bad as I didn't realize the starter relay was missing.

  7. #20
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,248
    Quote Originally Posted by bobwilson1977 View Post
    I did some more research. It would be impossible to re-use any of the old system in this as it works totally differently from a modern system. The innards are also permanently contaminated with oil and that will ruin any new compressor.

    So I have one option it seems. It will be a lot of work but not impossible. It would consist of removing the old condenser and disconnecting the original evaporator. I would then need to either find a donor fridge or find either used or NOS parts online, install the replacement modern condenser on the back, install a new evaporator up top and install a new condenser in place of the old. The fridge totally comes apart and the top comes off allowing you to get at all of the components. Seems like people give away 80's and 90's fridges around here all the time, so the costs to do this might be inexpensive but again- time consuming.
    I don't know what you may have read, but I know that back in the 1940's and 1950's my father did a boatload of SO2 (and Methyl Formate) conversions to R12 with no problems, mainly because the compressors all used the same mineral oil.

    I see no reason to abandon entire system as the evaporator, condenser and related tubing should work well with any new refrigerant and properly sized compressor.

    BTW...out of curiosity...does this unit have a high side float?

  8. #21

    Thumbs up

    Quote Originally Posted by icemeister View Post
    Units from that era typically used a "hot wire relay" as the primary starting component for the compressor. It's purpose was twofold. One to de-energize the start winding when the compressor comes up to speed and also to protect it from an overload condition.

    I suspect that's what once was in that junction box.

  9. #22
    Quote Originally Posted by icemeister View Post
    I don't know what you may have read, but I know that back in the 1940's and 1950's my father did a boatload of SO2 (and Methyl Formate) conversions to R12 with no problems, mainly because the compressors all used the same mineral oil.

    I see no reason to abandon entire system as the evaporator, condenser and related tubing should work well with any new refrigerant and properly sized compressor.

    BTW...out of curiosity...does this unit have a high side float?
    Hmmm.... interesting. I asked around a few places including one place that does restorations and they swore up and down that the oil would glob up with any other coolant. The other thing I was told was that these older units flooded the system which works a little different from today's systems and that I'd have to get a much larger compressor. I aint a pro so its all news to me.

    But if what you're saying is that nope- should be ok, I'd sure as hell rather modify the original system because that'd be a lot easier. The comment about the compressor made no sense because I did the conversion on the 1/8 hp compressor in there now and that works out to about 400 CFM. That's the same ratings on the 1/8 hp modern units I am seeing. This option would be a LOT cheaper than doing the whole stupid thing.

    Thanks for your all's help. I know I'm not a pro or anything, but this sure helps me a lot!~

  10. #23
    Here's some info that more or less seems to back up your statement:
    http://wc101.com/guides/refridgeration/page4.htm

    From the article it states:
    The biggest confusion is that a compressor is made for one particular refrigerant and CAN NOT be used for anything else. This is a myth it can be with a bit of care and effort. Something you will need to do is find out what refrigerant the compressor
    was filled with originally, this information leads us to know what oil it contained this is very important. If the compressor was charged with anything other than R134a the first time then its 99% accurate to assume that it contained mineral oil this is no a huge deal.
    So sounds like its sort of reverse of what Ive been told: Anything other than R134a in the old system and you're probably ok.

  11. #24
    I have a set of old GE reference books that date back to the 1940s. Get me a model and I'll look up the refrigerant type.

  12. #25
    Join Date
    Jul 2000
    Location
    Guayaquil EC
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    10,248
    Quote Originally Posted by bobwilson1977 View Post
    Hmmm.... interesting. I asked around a few places including one place that does restorations and they swore up and down that the oil would glob up with any other coolant. The other thing I was told was that these older units flooded the system which works a little different from today's systems and that I'd have to get a much larger compressor. I aint a pro so its all news to me.

    But if what you're saying is that nope- should be ok, I'd sure as hell rather modify the original system because that'd be a lot easier. The comment about the compressor made no sense because I did the conversion on the 1/8 hp compressor in there now and that works out to about 400 CFM. That's the same ratings on the 1/8 hp modern units I am seeing. This option would be a LOT cheaper than doing the whole stupid thing.

    Thanks for your all's help. I know I'm not a pro or anything, but this sure helps me a lot!~
    First let me say that I have never done one of these personally, but with any old system like this I would surely recommend changing the oil in the compressor. The original was standard refrigeration mineral oil and so I'd go with that for the new. Just replace whatever you take out.

    The flooded aspect is why I asked about the float. If it has either a high side or low side float (Google it), that means it's a flooded system. That doesn't necessarily kill the deal, but it's a point you need to be concerned with. Flooded systems only work well with single component refrigerants like SO2, R12 and the newer R134A. If it is a flooded system, I'd suggest going with R12 if you can get some.

  13. #26
    Quote Originally Posted by icemeister View Post
    First let me say that I have never done one of these personally, but with any old system like this I would surely recommend changing the oil in the compressor. The original was standard refrigeration mineral oil and so I'd go with that for the new. Just replace whatever you take out.

    The flooded aspect is why I asked about the float. If it has either a high side or low side float (Google it), that means it's a flooded system. That doesn't necessarily kill the deal, but it's a point you need to be concerned with. Flooded systems only work well with single component refrigerants like SO2, R12 and the newer R134A. If it is a flooded system, I'd suggest going with R12 if you can get some.
    Thanks again for the help. Unfortunately I can't find any info online about what the setup is inside the compressor. Its a GE CF-28-E16 compressor but again- its so old there's nuttin' about it out there. So- if this is a flooded system, is what you're saying is to go with R12 and call it a day? ( again assuming the stuff can be found) ? Would R134a be compatible seeing as how it uses ester oils?

    I have a set of old GE reference books that date back to the 1940s. Get me a model and I'll look up the refrigerant type.
    Thanks for the offer. Its an So2 unit as it had this listed on the manufacture tag on the compressor unit.

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