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Help with 1947 Kelvinator R12/charge leak


Premium Member
Mar 26, 2023
Model Number

Made my first post on this forum in another thread, https://www.applianceblog.com/mainf...-model-year-of-vintage-nash-kelvinator.95958/, and by research of the serial was able to identify my fridge as a 1947.

Hello and thanks in advance for any assistance or knowledge.

I'm working to restore a 1947 Nash-Kelvinator Fridge, a family heirloom bequeathed to me by my grandfather. It's an R12 capillary, hermetic, non-defrost system. It ran for years after my grandfather dropped in a 1959 compressor but recently the frost line is inching back towards the evaporator inlet, indicating a potential leak and evap plate temps are increasing. I recharged the unit with a few oz of R12 (legit R12, not 12a, hotshot, etc.) using the frost line method, I know this is not preferred but I didn't have a scale handy and being that it's not the original system or plumbing it would be a bit of a guess anyways. The unit does cool down nicely, going from ambient-empty 65°F to 28 only takes about an hour, which on an old beast like this seems pretty good. Similarly, when undisturbed, average air temp at four points in the chamber will cool at about 1° per minute when half-loaded with drinks, yielding a three to four minute run time. But, logging evap plate temps over multiple 24 hour periods shows a slowly increasing trend after the recharge - pretty sure I gave the charge enough time to settle in and balance out. Condenser coils are clean (were a bit dusty but recently knocked off with a horsehair brush), unit has plenty of airspace around it, and there are no evap or condenser fans to worry about. Thermostat was replaced by my grandfather, it is an air-sensing capillary style stuck to the side of the evaporator plate.

I've spent a good amount of time trying to track down the expected leak using a wand (admittedly a cheap one) as well as soap but it seems small enough to not be picked up. Similarly, I can't locate any signs of oil. All the usual culprits such as junctions, service valves, valve stems, etc. have been inspected and sniffed extensively. I've got a sufficient supply of R12 to fully service it multiple times but have not had luck finding anyone near me who is willing to try and identify the leak or do more than what I have done already. When calling around, those who have an understanding of what it is aren't willing to work on it, and those who are willing require the "year, make, model" so they can pack parts before they come Lol.

When operating, high side is about 130 and low side is about 5-8, with chamber at temp, normal thermal load, and ambient temp of about 75° F. R12 is not my expertise, but from the limited Google info I can find this is about normal on the antique system. If possible confirmation of this being normal, and not a indicator of a blockage or non-condensables would be appreciated. I've heard partial blockages on such systems can cause low-charge-like symptoms. The evap is aluminum plate and forms the icebox, condenser is steel, and there is a liquid line filter drier of unknown vintage installed. Temperature difference across the drier is minimal, only about 1°F so I don't it is clogged.

As far as leak detection, some have suggested using dye but I've never been a fan of the mess it makes or the possibility for it clogging. It's a simple, small system, so I'd like to keep it just freon and oil. I'm getting about down to my wit's end though, and my constitution is waning.

Any suggestions on how else to detect the leak? I don't have the equipment and can't find anybody willing to recover the system and do a nitrogen Purge or check vacuum holding abilities. Is 130/7 PSI during operation about right for such a system? I can't get good info on probable head pressures so it's hard to confirm if there's a blockage or I need to dig deeper into a leak.

Some of you may say it's not worth the effort, and price wise you're not wrong. However, value-wise, the fridge holds immense value as an heirloom, so I'm exceedingly and humbly thankful for any assistance.

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