hate to disappoint all you folks but....... I am an ASE certified AC specialist and have converted probably more than 800 cars since the R134a craze. Never had a system failure and all I do is make sure the o-rings are changed to be 134 compatible, be sure to use ester oil. there is no need to remove ANY of the old mineral oil at all, and as stated before, the 134a runs at a different pressure, so just use 80% of the reccomended amount of r12 and no problem at all.
I work with all these freons almost daily. (R-12, R-134a, R-22, R-502, R-401B, R-402A, R-404A) There are different types of refrigerent oil as mentioned. In a newly installed system, for best results use the recomended oil/freon combo's. Yes, you can add/mix different oil and freon and have it work OK for awhile. It's the long term effect that will eventually cause system failure. When converting freon in a older system not only the o-rings should be changed but all rubber hoses as well as a flush of all remaining componants (evap. cond. accum tank). When the new freon came out they claimed that the freon would deteriorate the inner rubber of the hoses. Therefore the hoses should be changed to the newer style with the inner liner. You can argue the mixing of oil/freon all day long according to your personal experiences not manufactures recommendation.
I agree with PART-TIME. This is one area that can become a big arguement because people have done it all kinds of ways and a lot of times they don't see the end result and so expect that thier way is perfect. Also there are probably more disagreements between 'ASE Certified AC Specialists' than anybody, so I take it with a grain of salt. Yes I am certified as well, by ASE and MVAC by Mainstream engineering. Anyway I would like to say a few things, knowing that people will disagree, but also people can do thier own research. There is no DROP IN replacement for R12. Freeze 12 is a blend like all the others. It's 70% R134a! Blends are bad because they can seperate. Also, legally you can't replace R12 with anything without changing the fittings. Why? Because shops with R12 recylcers get royally screwed when they recover Freeze 12 into thier 30 lb tank of R12. The way I see it is if you are going to change freons do the right thing and just go R134a. At the least change the seals and flush the system / replace the oil. Some compressors require replacement, others don't. It's best to find out, but sometimes people don't and get lucky. Bottom line is freon and oil mixing is nasty and I've seen what it can do. You may not blow up anything doing it the wrong way but it won't last as long.
Whatever you guys consider wrong and not lasting long, me old Caddie has been converted for right at 10 years now and hasn't blown a seal or hose yet. Not bad for a 30 dollar investment I would say. Most of the initial rules for retro-fitting ac systems were put in place to benefit the ac parts business but they were outsmarted in the long run and shown it is much less costly AND simple converting to alternative refrigerants.
Well, just so you know, I'm certified too. Plus, I'm also a certified HVAC tech with a 2 year degree from Auburn in Heating and Cooling. Anyway, you're wrong. Just because it works doesn't mean it's the right way to do it. If you want to do stuff like that fine, but don't encourage other people to do things the wrong way. Plus, the EPA put the rules into effect, not the EPA parts business and I don't think they really care about AC Suppliers making money. Just my .02 cents..
The rules were not put into place to make people money. Now THATS a consiracy theory. They may have been overly conservative. But beleive me there are compressors that cannot stand conversions. I worked for a Motorcraft distributor from 94-96 and we had HUNDREDS of MX-15 compressors failing immediately after conversions and Ford had bulletins sent out everywhere. Some GM compressors can't handle the new freon and oils either. But like I said some compressors take the difference no problem. Especially with the older compressors. Maverick units should be no problem.
