RX-7_ZX-9

According to their site @ Freeze 12 :

" FREEZE 12 requires no system flushes or lubricant change. It works with the existing R-12 lubricant"

RoyFifo

Yes, it works with lubricants such as Ester or Mineral oil, but it is not compatible with existing R12 coolant.

You need to evacuate existing R12 refrigerant prior to inputting the Freeze 12. Freeze 12 is a blend of gasses.

20% 142b and 80% 134a. It has the same reaction when mixed with R12 in system as 134a mixed with R12 des. I.E. it turns the lubricant into a corrisive acid that eats the hoses, Orings, as well as the seals in the compressor.


http://www.epa.gov/Ozone/snap/refrig.../refblend.html has a composition breakdown for all currently approved R12 substitutes.

82transam

iTrader: (18)

The price of R12 will vary greatly, its not made anymore so the only way you'll get it is to buy an old can, so the price is up to the person selling it. There is no standard price on it like R134a. I don't wanna sound like a tree hugger, but 134 is supposidly safe for the environment so changing over to it and getting rid of the R12 the right way makes me feel good.

bliffle

R134 is an amalgam of gases, each of which dissipates at a different rate! Thus, as they dissipate your system will degenerate. The heat capacity of 134 is a fraction of 12, so you need a bigger better AC system than what is in our old cars.

Stay with R12 or you will have inferior cooling, more frequent refills, and (very likely) damaged internals. On the other hand, if you just want a quick cheap fix to sell the car, convert to 134 and caveat emptor.

B

theteep

Here is my two cents worth:

I am an mechanical engineer and am a member of ASHRAE (American Society of Heating Refrigeration and Air-conditioning Engineers). I have access to many articles on the subject but most simply look at the cost/benefit of conversions. I found an article by Daniel E. Kramer, P.E. that addresses one of the major issues concerning this conversion: mineral (MO) or polyol ester (POE).

MO was used with R-12 systems because of its high miscibility (how the refrigerant transfers the oil) but it was found that the miscibility was much lower with R-134a. Manufacturers were concerned so they found a substitute, POE. Unfortunately, POE is not compatible with a lot of seals and other materials that are sometimes found in an older R-12 system. It is also very difficult to completely remove the MO lubricant from the system.

According to the articles that I found, Kramer tested MO in R-134a systems and found that although it was not as miscible as POE it was adequate. Here is a quote:

"Direct refrigerant replacement: Simply repairing the leak and replacing the lost CFC <R-12> or HCFC <R-22> refrigerant with the new HFC <R-134a> without changing the lubricant from mineral oil to POE may well be a viable option in most automotive air conditioners...Reports from respected laboratories have confirmed oral reports from service technicians about trouble-free replacement of CFC-12 with HFC-134a in auto air conditioners and ice makers..."

It is also true that R-134a will not perform as well as R-12 because of the relative size of the molecules (R-12 is much smaller than R-134a). I would recommend that the expansion valve be changed out as it will most likely lead to better performance.

I should also note that I have not performed this on either of my R-12 vehicles but if I have a major system failure I will be converting.

Hope this helps. Let me know if you would like a copy of the articles.

WackyRotary

I am thinking of doing this to my FC since the rubber o rings are bad on the compressor, you can actually see the dirt that has accumilated around the sealing areas, it has slowly leaked out over the past summer.

I'm going to take it off and replace the o-rings and use a air compressor to blow out as much of the r12 oil as I can. Then also get a new reciever drier located in front of the radiator as you should always do with a r12 to r134a conversion. Then finally have the system evacuated and be sure it wasn't leaking through the vacuum and remove all the mositure. And leave it for a hour or so, then add the new r134a and its oil and it should be good to go.

My mechanic friend says that 134a is about 70% as good as r12 for cooling, I can live with that compared to no a/c.

BrianHeston

I converted toward the end of last summer, and didn't end up using it once I got it done. This summer I've used it a few times and I'm satisfied with the results. It sure as hell beats windows and moon roof if you're just cruising around town, or if you want to have a conversation on the freeway. Only problem is my smoking habit, gotta have a window down sometimes no matter what...

Just my opinion,
BrianHeston

Sterling

Hey theteep- thanks!

mar3

iTrader: (8)

I always thought the R-134a molecule was smaller than the R-12 which is why the seals had to be replaced because a leak was inevitable for a system designed around the larger R-12 molecule. On the other hand, my degree was in Biology and none of my cars so far has ever had AC in the first place. The '83 GS I got from Teh has an intact system and a good compressor, so I'm thinking of the low-tech stuff I've seen here very seriously for the R-134a conversion.

mar3

iTrader: (8)

For all the peeps wondering, here's the compressor...the S and the D can just barely be seen between the 4 attaching bolts for the fittings...



What's the last word on this? Do you have good news for allus AC cheapos? I'd rather save some bucks for a Mallory fuel regulator...can't have too many lying around, y'know...

jimmdog

I did the 134 deal, On a 100 deg day in a black car it was useless. All that ruining your system with 134 is BS. I have never seen any evidince of this and I have done hundreds of conversions, on many makes and models.Stay with R12. I think you olny need 1 can some times you can buy the stuff at yard sales and flea markets