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#31
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Have a great day, |
#32
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true, he may have meant condensor instead of evaporator, but i think he nails it on why some people say it works fine and others are not satisfied.
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"the simplest answer is usually the correct answer" 1991 190e, 2.6 (helga) 91,000 mi |
#33
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So many opinions, just like an oil thread.....
Will it ever be worked out.............
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1981 300D 147k 1998 VW Jetta Tdi 320k 2001 Dodge Ram 2500 141k 1979 300D 234k (sold) 1984 300D "Astor" 262k(sold) Mercedes How-To and Repair Pictorials I love the smell of diesel smoke in my hair |
#34
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-Marty 1986 300E 220,000 miles+ transmission impossible (Now waiting under a bridge in order to become one) Reading your M103 duty cycle: http://www.peachparts.com/shopforum/831799-post13.html http://www.peachparts.com/shopforum/831807-post14.html |
#35
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Norm in NJ Next oil change at 230,000miles |
#36
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George
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George Androulakis Former Mb's: 1990 500sl R129 - 76k Original Miles - New project - Follow the saga http://90r129.blogspot.com/ 1990 190E 2.6 148k mi (sold) 1989 420 SEL 246k mi (sold) 1995 C220 175k mi (sold) 1992 190e 2.6 74k original miles (sold) 2000 c230 Kompressor 122k miles (RIP) 1996 C220 149k mi (sold) 2000 C230 Kompressor Sport 127k (sold) Current Cars: 2009 Mercedes c300 4matic 2006 Mercedes s430 2005 Jaguar XJR 2003 Cadillac Escalade |
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My education is in EE as well, but I grew up in my Dads shop. He started installing and maintaining auto a/c in the mid fifties. I was following him around then as a seven year old.
nglitz, That's not what satyr is talking about. He is talking about basic physics as it applies to energy. Cold is simply a lack of heat. You cannot move "cold" you can only remove heat. Heat is energy and can be dealt with. Cold is nothing and cannot be "moved." This is one of the very first principles described in most any book on refrigeration. satyrs main point is that cars are different with different parameters. Some have enough reserve a/c capacity to tolerate the loss of refrigerant capacity when switching to 134 and some don't. I agree with THAT PART of the 134 conversion philosophy. The part that causes me not to convert is that statistically, 134 conversions don't last very long for various reasons. I have actually reverse converted some cars that I originally converted to 134, later failing for whatever reason. Have a great day, |
#38
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Two reasons to stay with R-12
There are two very important reasons to stay with R-12 in our cars: (other than the fact that R-12 performs better)
1. R-134A systems require 'barrier hose' to prevent them from leaking over time. The refridgerent molecules are smaller, and can diffuse out of systems that are not designed for them. They also require different seal material that is typically not compatible with the seals and o-rings spec'd in R-12 systems. If you look at o-rings for R134a systems, they are green and a different material compared to the black rubber o-rings that are in R-12 systems. R-134A will destroy the black rubber o-rings over time and leak by. 2. Lubrication: The oils used in R-134A systems and R-12 systems are not compatible. To properly swap over, the R-12 system should be thouroughly flushed out if you are going to convert, and some systems really can't be effectively flushed without dissassembly. But this isn't really the point. The point is that the R-12 mixes and disolves its oil better and carries more through the system as it runs. R-134A has a lower saturation concentration of its oil (it disolves less of its PAG or Ester oils) and thus carries less lubrication through it as it runs. This really equates to lower lubrication of the compressor that is designed to run with R-12 if you convert, and thus shorter lifespan. At the lifespan of our current compressors, I don't believe that it is worth the risk of lowering the lubrication even by a small margin. R-134A designed compressors have a slightly different design to compensate for the lower oil concentration in the refrigerant. BTW, my background is mechanical engineering and thermodynamic systems design for nuclear power, but I have run into this issue before with other cars, like my old RX-7 that I tried to convert, and I did get the certification. I base my conclusions on my research of the issue both from engineering reference texts and automobile texts, and from experience of having performed maintenance and repair of both types of automotive A/C systems on many different cars I've owned over the years. I haven't had a single problem with the system on my 91 300E, but if and when I do, I'm going to repair it and recharge with R-12.
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On the plains of hesitation bleach the bones of countless millions who at the dawn of victory, sat down to wait, and waiting -- died |
#39
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In the early days of 134 conversion it was said that barrier hoses were an absolute necessity. In the case of replacing a hose in a system that uses 134 this has turned out to be absolutely true. In practice, however, we have learned over the years, that a hose that has lived a few years in an R12 system has a film or buildup of oil such that it will not significantly leak in a converted system.
Thanks for the info Strider. Have a great day, |
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