A/c flush of r12 to convert to r134a

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burnin4X4

10 Year 15 Year
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Mar 19, 2009
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I was told my system needs to be flushed completely before i replace with the r134 stuff. Does anyone know how this can be done at home or do i have to take it in to the shop. Someone said that if you mix the two the gas will become like gel....i need to recharge my system. It has no freeon right now due to an accident but i want to recharge the right way. Thanks for the help here in the forum...:)
 
The experts will chime in, but I found this info, and that is basically what I had done when converting my FJ60 to R-134a. The compressor was being replaced at that time, and figured we would do the conversion.

>>>>

Be extremely cautious about converting your old R-12 system to R-134a. Frequently, the new R-134a refrigerant will not circulate the R-12 oil and you will burn up your compressor. The R-12 mineral oil has chlorine contaminants that will destroy the R-134a PAG or POE special oil. The only way to reliably convert from R-12 to R-134a is to remove the compressor and flush out all the old oil with the new type of oil; then replace the old Receiver-Dryer or Accumulator with a new one; then flush out all the lines, the evaporator, and the condensor with special cleaner then vacuum to a steady vacuum; and finally charge with 70-80%, (by weight) of the original R-12 weight, with R-134a; and expect poorer cooling ability. It is much easier to keep the old R-12 system running with R-12 that is readily available via ebay.
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I found that with the R-134a, the system on the FJ60 wasn't cooling worth a darned. Not well enough for TX. I ended up updating the condenser coil and also added an aux fan. After all of that, my system worked very well, but it was expensive to do it right. Maybe the R-12 FJ80 systems convert better, but that wasn't my experience.
 
I don't know who is piping the information, but they are full of s***. Grab some conversion fittings, vacuum the system, add 2 ounces of pag 46 and charge to 80% of what is recommended for R12.

I still have the same drier and mixture of oils on two different cars, one a Land Cruiser, the other a Porsche, both will freeze you out.

I can't wait to hear what's advised when HFO 1234yf becomes the norm.
 
burnin4X4 said:
wow can a regular air guy do my system with an r-12? I would like to keep it like that after your comment seems like it would run better. Thanks.
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You can still find shops that will add R12 into the system, but usually at a high cost. Locally, a small can of R12 is about $60 then labor. Now there is a product called Freeze12 which many have used and have had mix reviews. Your supposed to be able to add it into a R12 system. I used it on my 4Runner years ago and it was wonderful. It was cheaper than R12 as well.

As far as cleaning out the system, it is advised. However, I have not seen systems gel up after mixing R12 and R134a (or others). Some oils are supposed to conflict with each other, but I dont know the specifics on those. Think about it though, if your going to vacuum the system dry of R12 and replace with R134a, your going to want it to last. You would want to change the rings out just for kicks on old trucks like our. It would be like replacing a water pump, but using the old gasket because it still looks good. Or replacing the radiator and not replacing the original upper/lower hoses because they are not leaking now.

Just my two cents. I hate it when I do a project and I skip something simple only to find it breaks down a few miles later.:bang::bang:
 
You guys have me thinking Hey TX Cruiser how did you vacuum your system did you take it in or you just added the R134a. I have already bought the stuff but wanted to make sure I did things correctly. Someone else told me that if I had not opened the system that I did not need to change the o rings. Well there seems to be alot of different information out there hopefully I will be able to solve the problems. Thanks again for the tips.
 
burnin4X4 said:
You guys have me thinking Hey TX Cruiser how did you vacuum your system did you take it in or you just added the R134a. I have already bought the stuff but wanted to make sure I did things correctly. Someone else told me that if I had not opened the system that I did not need to change the o rings. Well there seems to be alot of different information out there hopefully I will be able to solve the problems. Thanks again for the tips.
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I used my vacuum pump and manifold gauge

I wouldn't blow and go, 134a, oxygen and oil make an acid.
 
You simply hook up a set of gauges and connect the vacuum to it. There is a writeup on this forum for converting to 134a which has some helpful instructions. I cant remember how in-depth it goes, or even where it is at the moment. My search-foo is off tonight. The tools can be purchased simply at Harbor Freight (well, at least in the past) if you dont have a friend with the tools. A wise investment IMHO.
 
I went today and put two freeze12 cans in and wuala....it worked perfectly. My system works great. The key is if your system has not been opened than this is all you have to do if it was a R12 system. thanks for all the tips guys.
 
Personally I wouldn't mix 134a oil and mineral oil that is in R-12 systems. The two are not compatable. You take a big chance in burning your compressor out.

Best is to flush the system and use a POE lubricant. It will work with both systems.

Though I wouldn't even think of putting 134a in a system that was designed for R-12. 12 is not that hard to find and better yet freeze 12 is usually available at most Napa store. Last can I bought was like 10 dollars.

My system in my 93 is all freeze 12 and blows consistantly down in the low 30's on 90 degree days with the a/c on high. Usally takes about 5 min to get it really pumping the cold.
 
Here is the official information from DuPont regarding their Freon(TM) compounds:

This pdf talks about mixtures of r12 and r134a, which drier dessicants to use, which oils are compatible, which o-rings are preferable, and much more.

Basically, don't mix r12 and r134a because it causes high pressure in your system, the driers are not interchangeable, the oils are not interchangeable, and the O-rings are not usually interchangeable. But look for yourself.

http://www2.dupont.com/Refrigerants/en_US/assets/downloads/h45945_hfc134a_push.pdf


And here is a description of Freeze 12 and other alternative refrigerants. I haven't verified this so far.

Basically, it says Freeze12 is 80% r134a and 20% hcfc 142b (another freon-like compound), and that it is currently illegal for any epa certified techs to work on systems with other than r12 or r134a in them.

http://www.ebay.com/gds/Freeze-12-Refrigerant-R134a-/10000000005615895/g.html

In case this site becomes unavailable, here is information of interest (but there is no further information below except that from the site link above):


Thinking about using Freeze-12 refrigerant?

You may be surprised to learn that it is nothing more than a blend of R134a and HCFC 142.

Most of the "alternative" refrigerants are really nothing more than a slightly different blend with a fancy can. If you are unlucky, you actually get propane, butane, or some other flammable gas.

ALTERNATIVE REFRIGERANT BLENDS

Free Zone (RB-276). Supplied by Refrigerant Gases, this blend contains 79% R-134a, 19% HCFC-142b and 2% lubricant.
Freeze 12. Supplied by Technical Chemical, this blend contains 80% R-134a and 20% HCFC-142b.
FRIGC (FR-12). Made by Intermagnetics General and marketed by Pennzoil, this blend contains 59% R-134a, 39% HCFC-124 and 2% butane.
GHG-X4 (Autofrost & McCool Chill-It). This blend is supplied by Peoples Welding Supply and contains 51% R-22, 28.5% HCFC-124, 16.5% HCFC-142b and 4% isobutane (R-600a).
GHG-HP. Also supplied by Peoples Welding Supply, this blend contains 65% R-22, 31% HCFC-142b and 4% isobutane (R-600a).
Hot Shot\Kar Kool. Supplied by ICOR, this blend contains 50% R-22, 39% HCFC-124, 9.5% HCFC-142b and 1.5% isobutane (R-600a).
The suppliers of the alternative blends say their products typically cool better than straight R-134a in systems designed for R-12, and do not require changing the compressor oil or desiccant in some cases. Changing the desiccant to XH-7 is usually recommended if an R-12 system is converted to R-134a. The desiccant should also be replaced if a blend contains R-22 because R-22 is not compatible with XH-5 or XH-7 desiccant. The recommended desiccant in this case would be XH-9.

The suppliers of the alternative blends also insist the fractionation problem is exaggerated and do not foresee any major problems with recovering and recycling their products (recycling blends is currently illegal, but the EPA is reviewing its feasibility).

As it stands right now, recycling and servicing a system filled with an alternative blend is illegal.

Please, the best refrigerant to use is the one it was designed for.

I am a EPA 609 certified MVAC technician.

Please beware of using anything you don't know what it is.
 
So if one wanted to convert to R-124a the proper way, it sounds like you need:

-New 0-rings, what type? Are they standard size/universal? How many? Where do they go?

-New dryer/dessicant, what type? Where do you get it?

-Do you need new hoses?

-What is the procedure for cleaning the system of R-12 and associated oils?

Thanks!:beer:
 
CJF said:
So am I.

Took all of two beers and an hour long, open book online test. :meh:
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I am not a certified EPA technician, that was what the person who posted that info on Ebay claimed, and as I said, I haven't verified any of the info in that link. I was just trying to get some info out there as it looked like it might be useful.

I am not offering any opinion about what to do or how to do it or whether or not it should be done, only making other's opinions available. I want to convert my R12 to 134a also, and wanted to further the discussion.

Sorry for any confusion.
 
I unbolt the top via removing the 4 allen head screws. I have had good success using Ester oil on R12 systems, then if you lose the freon, you can add 134 without worrying about flushing the oil and the system out. Ester oil is compatible with both refrigerants. At least that is what my research discovered.
 
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