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Old 12-07-2000, 02:09 PM
Gene Wager
Posts: n/a
R-134 vs R-12 and moisture too

I've had the experience of having my mertz converted and the techs then converted back and told me I just wouldn't have been happy with the performance from the R-134. The reason they gave me for lackluster performance for the R-134 conversion was that the (over)design of the system was such that the heaver components didn't cool as rapidly. With 100+ heat in TX we want all the cool we can get + as quickly as possible. The experts don't recommend conversion if quick cooling is wanted (although they told me that eventually the R-134 would have also cooled the system sufficiently (probably about by the time I was turning into my garage). The R-12 keeps the car instantly cool even with the Rag-top on.
Second topic: getting all the moisture out of the system is essential to keep the water from reacting with the freon to form acids that will destroy your system (eventually). Definitely change the drier, and flush the system. R-134 conversion also requires a new expansion valve for the R-134.
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Old 12-07-2000, 05:26 PM
Registered User
Join Date: Nov 2000
Location: Jacksonville, FL USA
Posts: 113
I was told to stay away from those "conversion kits" that just change out the refrigerant from R12 to R134, apparently to use R134 you need a much stronger compressor. My father used one of those conversion kits on his Bronco and it didnt cool at all so he had it switched back to R12.
2003 Volkswagen Golf GL 24,000 miles. 1.9L I-4 TDI 5spd.

1986 300E. 115,000+ miles. 3.0L I-6 1st daily ride, around town only. (Gone)
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Old 12-08-2000, 06:55 AM
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Seeing these posts about going BACK to R12 are a little scary to me. This would require EXTREMELY thorough flushing and maybe a fresh compressor. the introduction of any R12 into an R134 is bad news and can cause some serious problems. These two compounds are to be kept completely away from each other. This is why they changed the fittings, and guage systems, so that you couldn't contaminate one with the other.

Just my thoughts,
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Old 12-08-2000, 08:55 AM
Registered User
Join Date: Oct 1999
Location: Tulsa, OK USA
Posts: 139

I had to answer some basic questions when I did my R134a conversions. I basically wanted a functioning AC in my cars when the temps got into that Oklahoma Summer of 90 to 108 degree heat so that I could be comfortable. While our temps in Tulsa get as high as Larry's we "normally" don't get as much humidity - sometimes - but not as much. If you want your AC to make ice or you want the interior to cool down in a matter of a couple of minutes, then my advice is with Larry - stay with the R12. R134a will not satisfy those criteria. If you don't want a little noise in your AC system when the temps exceed 100 degrees then stay with the R12 also.

In my case, I wanted to be comfortable ("ice was not requried") while driving and I wanted a system that I could maintain at a reasonable cost (R134a costs what R12 used to cost and still would except for..., never mind - don't want to start on that line). I also reasoned that since I keep my house temp in the 70 to 72 range in the summer cooling my cars to a similar range should be fine. For me it is - actually the interiors ofthe cars are cooler. R134a just happens to meet my perhaps limited criteria otherwise I would have stayed with the R12.

More of my .02 (or maybe .05) here

Dan Taylor/ Tulsa, OK MBCA
'84 300D/'90 Jaguar XJ6/XJ40
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Old 12-08-2000, 01:36 PM
Posts: n/a

I can certainly identify with your comments. I headed into the R134 deal about three years ago, starting with my old truck which I couldn't justify spending what appeared at that time to be "big bucks" for R12. I got guages, a 35 pound can of R134 and even upgraded my vacuum pump to gear up for changing over my older vehicles.

The truck didn't come out too bad, but I now have a leak I will have to trace, causing me to spend even more on a UV leak detector.

The 123 came out not bad, but the R134 expansion valve ended up being cheap crap and leaked. With everything on it in proper shape it still leaves much to be desired when it's 108.

Getting the interior making ice cubes in 2 minutes is certainly not part of my criteria, since my commute is over 90 miles one way. But it needs to make it to bearable temp in 10 minutes or so. R134 in my truck or my 123 car struggles to do that on a hot day.

An original R134 system is a different matter. The condensor is larger to compensate for the less efficient refrigerant. So these cars work okay. It's the retrofits that are usually a challenge.

If I could go backwards, I would have spent all that money on R12 instead of equipment and the like.

My $0.02,
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Old 12-14-2000, 08:22 AM
Posts: n/a

Your common sense is right on the money.

Have a great day,
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Old 04-04-2001, 09:16 AM
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When my Z was converted to 134, the aux fan was rigged to go on with the compressor. This resulted in a much cooler air than is possible with the normal 134 operation.
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