OK, I'm into the A/C to replace my leaking Evaporator, and the related parts with the job[drier, etc] Here's my question, has anyone done a R-134 conversion to a high mileage Gen 2 Montero from the stock R-12 freon? Did you run with this conversion long enough[like several seasons]to see how it performs when compared to the cooling of the R-12? Any downside like shortened compressor life due to the high pressures that R-134 normally has on the high side of the A/C system? Thanks for any info you can shed. <img src="/forums/images/graemlins/cheers.gif" alt="" />

I've not done the conversion on a Monty, but I have done it on many road tractors. A system converted to R-134 does not cool as well as the R-12, but the difference is negligible. And in the Monty you won't notice it much. Also, before everyone gets up in arms, the systems that are R-134 from the factory cool just as well as R-12. The conversions are the only time I ever encountered a difference. As far as reliablity you should not run into any problems. And of course the biggest factor is the cost and ease of getting the 134. The only way you can get the 12 is take it to a shop or be certified on A/C and then it is more expensive. I hope this helps.

Thanks, I too have done R-134 conversions and have worked on A/C systems since the late '80s. Along with using Ester Oil as your conversion oil for the system, the usual suspects are a slight drop or lack of cooling out of the condensor if it's sized or tubed for R-12 when you convert the system over to R-134. Evaps, valves, lines are usually not an issue. O-rings can always be changed over to R-134 material if needed. So, my usual biggest concern is whether the compressor can handle the higher pressures that R-134 puts on the system, and if there's shortened service life from that since compressors aren't usually cheap, even with a rebuilt.
Getting R-12 isn't an issue either, aside from gulping at whatever the wholesalers are charging for a 30 lb can each year <img src="/forums/images/graemlins/smile.gif" alt="" /> Yeah, R-134 at Pep Boys retail, or from your jobber in a 30 pounder is much cheaper, so I'd like to go with that if possible. <img src="/forums/images/graemlins/patriot.gif" alt="" />

Houstan
I have ran R134 for the past five summers. It works great in my 89. I did not have any leaks and still don't. No problems with the compressor yet.

Has anyone tried these?
Maxi-Frig
Freeze 12

Did the conversion on my BMW 325i a few years ago -- kept it for a couple of years after doing it (wife wanted a 4x4 so the BMW had to go) -- anyway, no issues, no problems, couldn't tell the 134 cooled any less than the 12.

Terry

I converted my SWB over last year. I did replace all the "O" rings and flushed it before changing over. I installed ester oil and 1.7 lbs of R134,(MAC recommends 85% of R12 capacity). It worked great last year with no problems, There was very little increase in pressures and it cooled that SWB very well.
The feedback that i am getting on all the other alternative refrigerents is not good.I know thats a broad statement but it was from what i consider reliable sources. However try it. If it works, let us know.

STAY AWAY FROM FREEZE 12 IT HAS KEROSENE OR SOME SORT OF GASOLINE IN IT. DO NOT USE IT. <img src="/forums/images/graemlins/scared.gif" alt="" /> or at least thats what I learned in my 3 years in selling parts.

Thats not Freeze 12 you are thinking of, Freeze 12 is made up of 85% 134a w/ a heavier gas to push the mineral oil in the system. But that is true, there was a big scare back in the mid 90's, jack leg refrigerant mfrs were using propane and a type of butane? (I think) It cools well but when you get in a wreck or have a leak in the engine compt <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/zombie.gif" alt="" />

Thanks to everyone who posted in response to my questions.
The deal is done, I installed the Evaporator, expansion valve and new rec-drier at work last night, and stuck with R-12 for now. If anyone wants a 'blow by blow' posting on how to R&R the evap in a Gen 2, along with part numbers and O-ring and hardware listings, let me know and I'll write up a service/job description for the board. I used no air tools, took my time, and put the system under a vacuum for 25 minutes since it had been leaking for so long and was now also open to outside air with the repair work. Total time was 2 1/2 hours, start to finish. <img src="/forums/images/graemlins/cheers.gif" alt="" />