Can I convert my R12 gauges to R134a?

[Zeke]

I have a nice set of professional gauges but my last R12 car is gone.

Adapters? Swage new fittings? Or is it cheaper to just buy a new set?

I think I looked into this before and just got confused. I'll never use these gauges for R12 that I can see.

 

[rkevins]

you can get adapters for your hoses

 

[oldtools]

You can not use the R12 gauge for R134. You have to buy a new set. You may still use the R12 gauge for home AC (it is still R12).

 

[Zeke]

You can not use the R12 gauge for R134. You have to buy a new set. You may still use the R12 gauge for home AC (it is still R12).

I think I'd heard that, but why? Do the dials know the difference? This is a 3 hose system with a manifold. US made.

I don't have central home A/C.

 

[Charles (in GA)]

I considered the same thing several years ago when I installed an add on 134 system in my Ranger Pickup. Decided to buy a new set. Went to Advance Auto parts, looked at what they had, and bought one of the nicer sets. Works real nice. Not too expensive. I was in a hurry to charge the system or I would have shopped more, but probably would not have saved much.

Charles

 

[NHBandit]

You can not use the R12 gauge for R134. You have to buy a new set. You may still use the R12 gauge for home AC (it is still R12).

Why ? And don't say because the fittings are different.. we know that. I also have a perfectly good set of MAC R12 guages & manifold that are gathering dust.

 

[Harix]

Buy the new gauge set. It's cheaper than buying just adapter fittings.

 

[Bobdog]

You can not use the R12 gauge for R134. You have to buy a new set. You may still use the R12 gauge for home AC (it is still R12).

Wrong and wrong.

 

[pop pop]

^^^^^(Harix) This. The pressure gage doesn't know the difference. The back panel would have the correct help for the ref. you are using and possibly prevent confusion. But 30# is 30#. It won't be cheaper, but you could buy new gages with 134 back plate and new fittings.

 

[MikeF2316]

You can not use the R12 gauge for R134. You have to buy a new set. You may still use the R12 gauge for home AC (it is still R12).

Sure you can with proper adapters. R12 wasn't used in home AC, back in the day, R22 was the standard. Those systems used the same fittings as R12 systems in cars, so one gauge set did all. (New home system standard is R410a.)

 

[joedodge]

Yes you can infancy the set I have has adapters. Bought at a local refrigerant parts house, they work just fine.

 

[Carguy99]

yes you can they sell adapters.... its Ok you have my permission
If the have temp markings on the gauge on the inside of the pressure reading , those will be wrong ( they will be calibrated for r12 ). but the earth will still go around the sun.

 

[oldtools]

I think I'd heard that, but why? Do the dials know the difference? This is a 3 hose system with a manifold. US made.

I don't have central home A/C.

For a given temperature, the two fluids produce different pressure. If you use the R12 gauge at 70 degree with R12, the pressure will be different if you use the R12 gauge with R134 at 70 degree. You can use a R12 to R134 conversion chart, but it is not convenient. You also need adapter to fit onto R134 system.

 

[oldtools]

Sure you can with proper adapters. R12 wasn't used in home AC, back in the day, R22 was the standard. Those systems used the same fittings as R12 systems in cars, so one gauge set did all. (New home system standard is R410a.)

Yes, I think it is R22 instead of R12. My memory is failing me.

 

[Zeke]

yes you can they sell adapters.... its Ok you have my permission
If the have temp markings on the gauge on the inside of the pressure reading , those will be wrong ( they will be calibrated for r12 ). but the earth will still go around the sun.

By "temp" markings do you mean the dual scale that shows for R12 and R22?

I guess I should take a pic, but the outside scale is pressure in black. The inside scale is in red with 2 scales. I can't seem to be able to read the brand.

Could an HVAC student use these? I'd be willing ti donate.

 

[ChevyEFI]

Find a tax-write-off donation venue for the old ones. You got your moneys worth.

Buy new ones that suit 410a and 134a. I've had a moderately priced set of mastercools for 7 or 8 years.

What to do for all the alternative refrigerants (who else wants CO2 at it's high-pressures to come in play?!!) is another story.

 

[Jbullfrog]

I have a set of Mac gauges that do both R12 and 134a. They were sold that way and have 134a quick connects with acme ******* for the lines. I got them in 1999 and still have the "dual gauge" packaging somewhere.

 

[MikeF2316]

By "temp" markings do you mean the dual scale that shows for R12 and R22?

I guess I should take a pic, but the outside scale is pressure in black. The inside scale is in red with 2 scales. I can't seem to be able to read the brand.

Could an HVAC student use these? I'd be willing ti donate.

Mine are marked for R12, R22 and R502. I never use those temperature scales anyway, so I don't care. You're going to want to know what your pressures should be, and compare them to what they are. And in automotive use, the weight of what should be in the system, it's best to remove all the old and put in the exact correct amount.

 

[rlitman]

yes you can they sell adapters.... its Ok you have my permission
If the have temp markings on the gauge on the inside of the pressure reading , those will be wrong ( they will be calibrated for r12 ). but the earth will still go around the sun.

Yes. The only catch with recycling r12 gauges is that the oil is different in r134a, and you could potentially spread a little contamination this way. Just something to think about, but probably not a big deal. Fluorescent dye in a system is probably worse.

 

[monkeyspanners]

In theory there is a risk of chlorine from the old R12 contaminating the pag oil in new R134a
systems.

http://www.autofrost.com/hotshot/

I have never seen it happen but i'm told the potential is there.


If they were my gauges and i was determined to use them i'd just get a new set of hoses with the correct adaptor and a couple of R12 to R134a conversion adaptors so i could park the hoses as normal. I'd probably give the gauges a good rinse out with some suitable cleaner and a good vacuum before using.

There a loads of free pressure temperature chart apps for phones, personally prefer the Bitzer one but Danfoss and Emerson et al make them too, or even an old fashioned slide rule would do to convert the pressures into temperatures.

 

[Bobdog]

For a given temperature, the two fluids produce different pressure. If you use the R12 gauge at 70 degree with R12, the pressure will be different if you use the R12 gauge with R134 at 70 degree.

True, but that's why they make P/T charts. The pressure indicated on the gauge remains the same no matter what the refrigerant is.

http://www.arkema-inc.com/pdf/fluorochem/P-T_R-134a.pdf

 

[MikeF2316]

In theory there is a risk of chlorine from the old R12 contaminating the pag oil in new R134a
systems.

http://www.autofrost.com/hotshot/

I have never seen it happen but i'm told the potential is there.


If they were my gauges and i was determined to use them i'd just get a new set of hoses with the correct adaptor and a couple of R12 to R134a conversion adaptors so i could park the hoses as normal. I'd probably give the gauges a good rinse out with some suitable cleaner and a good vacuum before using.

There a loads of free pressure temperature chart apps for phones, personally prefer the Bitzer one but Danfoss and Emerson et al make them too, or even an old fashioned slide rule would do to convert the pressures into temperatures.

You'd think the risk of contamination would be a lot higher from the old hoses in all those cars that came from the factory with R12, the ones built before 1993 - the actual hoses from the AC system that had R12 at pressure inside them for years...

 

[rkevins]

Ask a HVAC man if he has a set for each type of refrigerant, if you need the temp download a pressure / temp chart. there are also apps for p/t charts.

 

[bonneyman]

With R-12 and R-134A, it's the lubricating oil that is the potential problem, not the pressure readings. 12 is mineral oil based lubrication, 134A is synthetic non-mineral oil lubrication. They don't mix, and when mixed, cause all sorts of problems. It's the same with residential HVAC (R-22 vs. R-410A)

Literally, your 12 gauges (or 22 gauges) will measure 134A pressures. A PSI is a PSI, regardless of the gas. But you don't want to regularly switch between two different gases like that, because of the potential oil cross-contamination.

 

[firebox40dash5]

With R-12 and R-134A, it's the lubricating oil that is the potential problem, not the pressure readings. 12 is mineral oil based lubrication, 134A is synthetic non-mineral oil lubrication. They don't mix, and when mixed, cause all sorts of problems. It's the same with residential HVAC (R-22 vs. R-410A)

Literally, your 12 gauges (or 22 gauges) will measure 134A pressures. A PSI is a PSI, regardless of the gas. But you don't want to regularly switch between two different gases like that, because of the potential oil cross-contamination.

True, but if you no longer have any need for the R12 capability, a one-time swap shouldn't pose an issue.

 

[malibu101]

True, but if you no longer have any need for the R12 capability, a one-time swap shouldn't pose an issue.

Except for possibly the first time.

 

[TheGrooveking]

I too have been contemplating a new manifold/hose set bit wondered if you can flush/clean the oil residue out of them? Maybe denatured alcohol and then blown through with clean compressed air.

TheGrooveking

 

[monkeyspanners]

You'd think the risk of contamination would be a lot higher from the old hoses in all those cars that came from the factory with R12, the ones built before 1993 - the actual hoses from the AC system that had R12 at pressure inside them for years...

I'm not sure i understand you, there wouldn't be any PAG oil in an old R12 system to react with the chlorine from the R12 as the systems run with 5gs mineral oil.
I believe the conversions from R12 to R134a would use POE oil which is synthetic like PAG but will work fine with R12 and R134a.

Like i say i have never seen any contamination problems happen but i work mainly on commercial systems.


I might have a bit of a play with some old systems and make a vid for my youtube channel of oil contamination if any occurs!

 

[Zeke]

Found these:

Seems about right. Keeps the integrity of the old set up should I ever need it.

 

[mrtoolfool]

Yes you can infancy the set I have has adapters. Bought at a local refrigerant parts house, they work just fine.

Ditto

Been using them for 10 plus years and never had a problem.

 

[MikeF2316]

I'm not sure i understand you, there wouldn't be any PAG oil in an old R12 system to react with the chlorine from the R12 as the systems run with 5gs mineral oil.
I believe the conversions from R12 to R134a would use POE oil which is synthetic like PAG but will work fine with R12 and R134a.

Like i say i have never seen any contamination problems happen but i work mainly on commercial systems.


I might have a bit of a play with some old systems and make a vid for my youtube channel of oil contamination if any occurs!

Well, I can pretty much guaranty that any new compressor is going to come with PAG oil in it, so in that case there's going to be some residual in the system even if it's changed. It's been years since I've done any conversions, but as I recall most auto makers recommended PAG oil be used in the conversions. Most of the aftermarket kits had POE in them though. There's lots of conversions running PAG in old R12 systems with no problems.
The rationale is that the old mineral oil will just sit in the low points of the system and the new refrigerant and oil will simply flow over it.