# R12 To R134A



## CamperAndy (Aug 26, 2004)

Just curious if any of you have much first hand experience changing from an R12 system to an R134a AC system? Looking for comments on just topping up the system with R134a on top of the R12 or does the system have to be completely vacuumed? Also once converted comments on how well it does.


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## Nathan (Jan 2, 2007)

I assume we are talking Auto A/C????

Car AC systems are no different than trailer's LP systems. When you need more gas, it's easiest just to upgrade.....

















Ok, seriously, I think they run at different line pressures, so you'll probably want to check on that first....


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## N7OQ (Jun 10, 2006)

Don't mix r12 wit r134a not a good thing. R134a uses a different oil "Ester oil" R134a will not carry the r12 oil so you will have to replace the oil too.

Another drop in replacement for r12 is propane it will carry the r12 old and will even cool better. Only problem is it is not DOT approved for on road use. Mt Brother in-law uses it in farm equipment all the time since that equipment does not have to meet DOT rules. The reason DOT will not approve it is because it is flammable, but there is really not that much in a motor vehicle AC.

Also r134a requires you to change the fittings, and maybe the dryer, expansion valve, or accumulator depending on your system. SO you recover the old r12 per EPA, make retro fits, replace oil run some nitrogen through it to remove any moisture then draw a vacuum and measure in your refrigerant.


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## CamperAndy (Aug 26, 2004)

N7OQ said:


> Don't mix r12 wit r134a not a good thing. R134a uses a different oil "Ester oil" R134a will not carry the r12 oil so you will have to replace the oil too.
> 
> Another drop in replacement for r12 is propane it will carry the r12 old and will even cool better. Only problem is it is not DOT approved for on road use. Mt Brother in-law uses it in farm equipment all the time since that equipment does not have to meet DOT rules. The reason DOT will not approve it is because it is flammable, but there is really not that much in a motor vehicle AC.
> 
> Also r134a requires you to change the fittings, and maybe the dryer, expansion valve, or accumulator depending on your system. SO you recover the old r12 per EPA, make retro fits, replace oil run some nitrogen through it to remove any moisture then draw a vacuum and measure in your refrigerant.


So how much is all this and how do you pick a trustworthy place to do this. I do everything I can on my cars but AC work is a bit of a black art. I asked the dealer and they just said evac and refill. It is not working that well now, though it did work well at first.


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## N7OQ (Jun 10, 2006)

CamperAndy said:


> Don't mix r12 wit r134a not a good thing. R134a uses a different oil "Ester oil" R134a will not carry the r12 oil so you will have to replace the oil too.
> 
> Another drop in replacement for r12 is propane it will carry the r12 old and will even cool better. Only problem is it is not DOT approved for on road use. Mt Brother in-law uses it in farm equipment all the time since that equipment does not have to meet DOT rules. The reason DOT will not approve it is because it is flammable, but there is really not that much in a motor vehicle AC.
> 
> Also r134a requires you to change the fittings, and maybe the dryer, expansion valve, or accumulator depending on your system. SO you recover the old r12 per EPA, make retro fits, replace oil run some nitrogen through it to remove any moisture then draw a vacuum and measure in your refrigerant.


So how much is all this and how do you pick a trustworthy place to do this. I do everything I can on my cars but AC work is a bit of a black art. I asked the dealer and they just said evac and refill. It is not working that well now, though it did work well at first.
[/quote]

Well some can get away with just remove and replace and with others it works but not as well as R12. When they first stopped making 12 a lot of people were doing the change over and a lot of knowledge was floating around about it. Now that there are many years of 134a use there is not as much of a demand for the retro fit. If I still had a r12 car and needed to replace the freon I would have used propane and called it a day, no oil change and it will cool better than 12 and I would say the heck with the DOT. But I doubt you would find a shop who would charge a system with propane for fear of getting a fine. I would call different shops and see if anyone there is familiar with what is really needed to do it right. If your system was working good on 12 before you started then it may need more than just a change out to get it to work.

When they evacuated your system did they remove the old too? You need to be using ester oil of you will ruin your compressor. You can get a EPA 609 certificate easy can take the test on the internet pay the fee and get a certificate then you can do your own work but it is the equipment that cost and just to do it for your own use would be out of the question. Unless you was rich.

If you lived close to me I would do it for you I can get all the equipment from work, but my best suggestion is to do as much research on the internet about your car or truck about the retro fit and then when you talk to the guys at the different shops you will know if they really know what they are talking about or just blowing smoke. Man a Dealer should know what to do they have all the info at their disposal. Keep us posted.


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## N7OQ (Jun 10, 2006)

Hers is some good reading on the EPA site for doing AC retrofits Click here


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## aplvlykat (Jan 25, 2004)

To bad you are not closer. I still have around 25# of r-12 left in a 30# can. Like evryone else already told you r-134 is a different animal altogether. Different oil, seals and tx valve. If you can find a newer compressor that will fit and is set up for r-134 then the rest is fairly straight forward. New r134 tx valve, dryer and purge the lines, fill it with r134 and you should be good to go. The hard part is finding the right compressor. good luck, kirk


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