Actually, It would be more accurate to say that what was said is  "you can do it, but if you don't do it correctly, you will have trouble down the road."  Sounds reasonable to me.

It seems intuitively reasonable that the performance with R-134 is going to be dependent on the individual vehicle characteristics (capac ity)  and the region you live in (humidity and temperature.)   15% less efficient is not going to be noticible in some areas and vehicles, but will be very noticable where the situation is such that the existing R-12 system is at or near its cooling capacity. 

I think the main point is that R-134 is not a plug-and-play solution when done correctly.

Todd

'88 Westy.

----- Original Message -----

From: "Jim Felder" <jim.felder@GMAIL.COM> To: vanagon@GERRY.VANAGON.COM Sent: Tuesday, June 11, 2013 5:23:25 PM Subject: Re: AC Question

On Tue, Jun 11, 2013 at 6:52 PM, Keith Hughes <keithahughes@yahoo.com>wrote:

> R-134A doesn't cool as well in an R-12 system.  You really need a more > efficient condenser if you want good performance.  Additionally, R-134A is > not compatible with mineral oil used for lubricant in R-12 systems, and > typically R-12 compressors are not compatible with POE/PAG oils used for > R-134a from an internal seals perspective.  Also PAG and Mineral oils form > a very funky mess, so if you're not going to flush the system first (which > you should) use POE not PAG oil.  You must change the receiver/drier > anytime you open the system, and especially when changing oil/refrigerant, > if you don't want a time bomb waiting to blow (we're talking $15 here). >  Also, expect the R-134A to leak, as the stock hoses are not barrier hoses, > and 134A will leak out over time. > > > Well, here we go, the inevitable stream of reasons that you can't do something that everyone is already doing. I have done about six cars and I didn't do any of this stuff and I really can't tell any difference in actual cooling although I don't argue with the engineers who tell me that R134 is 15% less efficient than R12.

The R134 does find leaks that R12 doesn't, but you can put in a refrigerant with some sealing capacity if that is the case.

Jim