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Converting R12 guages to R134a

GM Guy

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Hey all,

I was needing a set of R134a guages (been bumming dad's, and they leak) and finding a set of ones old enough to be all metal (handles included) is proving difficult.

I have seen conversion fittings advertised (R134a quick couplers with R12 hose connectors) and was wondering about buying a nice set of R12 guages off ebay and these fittings and making a set of R134a guages.

If I do this, do I have to worry about anything else? I have heard people talk about oil embedded in the hoses, is this an issue? If so, do I just make sure to run some universal oil through, and try to limit my charging to farm equipment with older robust compressors (A6 Delco and 2 cyclinder tecumseh) for the first couple charges?

I eventually need to charge some of the GM pickups in the fleet, 95-2006 so I definitely dont want to hurt them.

Any input appreciated,
thanks!
 

79jasper

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I bought the hf kit.
So far seems to be fairly quality. (Can't believe I just said that lol)

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

THEFERMANATOR

FRANKENBURBAN
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My gauge set I got from MAC was an r-12 set with the screw on adapters. Oil getting into the hoses isnt an issuebecause the oil has to citculate over time to work its way into the hose liner. For gauges this isnt an issue since oil isnt going to get circulated through the hoses.
 

Will L.

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The difference in r12 and r134a is 2 parts. Different oil, which like Ferm mentioned, does not affect the gauge set up or hoses.
The other is the refrigerant it's self. The molecules are smaller so the hoses are made of a tighter compaction to deal with the newer 134a, as well as the orings.

Over an extended period of time the r12 hoses could in theory leak. In theory. Leaving them in the sun for a day is far more likely to speed up the process.

Harbor freight gauges themselves are not very accurate- I have a new set in my garage now, but if you are after getting it done simple and cheap- go that way. The new ones I just got seem to be off 3%.

If you are after maximum efficiency, buy Mac, Snapon, or Robinaire.

If I were doing A/C for a paying customer, I would use top end gauges to ensure they are getting every last penny of their value, because I hate the idea of giving a paying customer 99% of what they pay for. nit picky, because a good A/C tech can do a better job with cheap gauges than a hack with the best equipment, that my $.02 (give or take 3%)
 

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FRANKENBURBAN
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I would buy a used set of snap on gauges, rebuild them, and put on a set of cheap hoses and adapters before I bought harbor freight ones. That beind said, most of the time I don't even hook the high side up(to great of a chance of it leaking if I mess with one to chance it), so the low side is all I normally check anyways.
 

Will L.

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If you have a regular, good snap on guy- then ok. But if not, then no- snap on uses proprietary connections and will not work with off the shelf parts most of the time with their gauges.
Mac, Matco, Cornwell, Robinaire, etc all use standardized threads, connectors, seals and orings. I used to carry a lot of Snapon only stuff on my Mac truck for customers that had crappy snappy guys. My route crossed 4 snap on routes.
 

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FRANKENBURBAN
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I know my snap on gauges use a syandard -4 hookup for the hoses, same connection as the r-12 hookups most used on the low side, and industry standard for home hvac. Everything internally is all proprietary though, but you can't beat the smoothness and easy close of the snap on gauges.
 

GM Guy

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Well, I bought a nice looking set of Made in USA Robinair R12 guages with all metal hand wheels, and a much newer looking set of Yellow Jacket hoses, and also have a set of R134a conversion fittings on the way. hopefully in it all less than 65 bucks.
 

WarWagon

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I replace the low and high side valves on every vehicle I work on: EVERY SINGLE TIME! Too many times I remove the hoses and the valves are spraying R134a everywhere. Let alone the slow leaks from the valves.
 
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