R134a vs R12 1

[PLeon]

I find that all R134a systems are not providing cold air as fast as older R12 systems. I remember R12 systems that would pump cold air withing seconds after start up. Is this true or am I imagining things?
TIA,
Leon

 

[Comcokid]

I've heard that there is some investigation (in Europe, I think) of using CO2 as a refrigerant. Nontoxic and nonflammable. CO2 is a greenhouse gas, but using in auto AC would temporarily sequester some of the gas in cars. Presently, excess CO2 from industrial processes is released to the atmosphere.

 

[GregLocock]

meanwhile, to continue the (accurate IMO) conspiracy theory, gaseous hydrocarbons make perfectly good refrigerants and are compatible with current technology.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[SMOKEY44211]

I read in several books that the invention or formulation of what has become known as R-12 was credited to Thomas Midgley (same fellow that is credited for the developement of tetraethyl lead that was used in gasoline). He worked along with Charles Kettering at DELCO labs which was under the GM coorperate umbrella. There was a large financial interest in GM held by Dupont. As a result of his work household refrigerators became common. It amazes me that some little birdie can whisper in a politicians ear "the sky is falling" next thing you know product is banned throughout the world. Conspiracy? More then likely. What to do about it? I'm open to suggestion.------Phil

 

[Comcokid]

R134a from a cooling and reilability standpoint doesn't seem too bad. The problem is the PAG lubercant used with it. It is extremely hydroscopic and breaks down becomming corrosive if it azorbs moisture. Sometimes repairs entail replacing EVERYTHING, compressor, condensor, evaporator, hoses, and all associated piping! I'm sure this makes Detroit, parts dealers, and repair shops happy, because the expense of repairing a bad out-of-warrenty AC makes cars more disposable. A more "Green" way to go would be to make cars last longer, but that doesn't create more pay for automotive CEO's. They make money only if used cars are crushed.

In the old R12/minerial oil systems, moisture intrusion really only meant you needed to replace the dryer, pull a vacuum on the system and refill. If a system was abused to the point of dessicant breakdown, little more than a dryer, compressor, and system flush might be needed.

 

[swall]

In my experience, PAG is not that hydroscopic. Certainly not as bad as glycol ether brake fluids. We used to call PAG "goose grease", since it was hard to wash it off your hands.

 

[pennpoint]

Swall,
Simple alcohol, works really good for clean-up as many brake shops found out long ago.
To the point: We all are beyond R-12, R-22 and have replacements for both now, stop lamenting and move on, your best bet is to provide the best service to your customers now and in the future for brakes...same goes for AC...


Best regards
pennpoint

 

[rmw]

The thermodynamics are that R-134 doesn't perform as well as R-12 in the older R-12 systems because the systems were designed with respect to the surface areas of the evaporator and condenser for the thermodynamic characteristics of R-12. In systems designed for specifically for R-134 with larger surface areas, the systems work just fine.

With most of the older R-12 systems gone, converting and oil compatibility issues are way in the past (except for some of the old vehicles sitting in my driveway that still use R-12 but I squirrled away enough to outlast them, I hope).

rmw