A/C refrigrant, some answers

[srubano@xxxx]

[MODERATOR'S NOTE: The Freon vs R-134, etc discussion seems to come up every summer when the temperatures warm up a bit. This topic has a lot of coverage in the archives, and although it is informative, has little that is DeLorean-specific. Further posts on this (if any) will be scrutinized for content that is specific to the DeLorean.]



I thought I might be able to answer few questions on the A/C 
refrigerant topic.

R-134a: In order to convert to it you will need to replace the 
following; All rubber gasket/seals (R-134a will eat away at the 
original ones that were designed for the R-12 over time), the 
Drier/Accum (since the old one will have R-12 oil in it) and the 
valves....that's all you need to do. If you want to take it one step 
further change the Orifice tube, there is a new redesigned one 
especially for R-134a that is a "variable valve" orifice tube that 
will make it colder believe it or not. The one that's in the system 
now is a standard fixed orifice tube. It's not wrong that someone 
would recommend replacing the compressor and the evaporator since 
professionals recommend it. By replacing the compressor to one that 
is designed to handle the R-134a, you will make the system more 
efficient?same thing if you replace the evaporator to a larger one 
with the same BTU rating. Yes the R-134a requires higher pressure but 
it shouldn't damage any components unless it is over-
charged/incorrectly done. 

There is a new alterative to the R-12 out now that is better than the 
R-134a and requires less pressure and is much colder and cheaper, 
It's called FR-12. From what I understand the R-12 in a few years 
will be completely phased out and a lot of refrigeration/ A/C 
mechanics are moving away from it since it's getting more expensive 
and harder to obtain. You will still need a licensed A/C technician 
to do the job, it's not for sale over the counter.

Here's some text from a website I found on the net regarding the 
conversion to FR-12:

"To convert a properly functioning automotive R-12 system to FRIGC 
(FR-12), an installer must: 

Recover and recycle the R12; 
Evacuate the system (for approximately 30-45 minutes); 
Add approx. 2 oz. of Ester (POE) oil 
Charge the system to approximately 80 to 90% of the R12 capacity and 
install the under-hood "system identification retrofit label". 
Install retrofit fittings on the high and low side service ports; 

It's that simple! In some cases, it may be necessary to adjust the 
cycling pressure switch on CCOT systems for optimum performance."

For more info: http://www.frigc.com/auto/faq.shtml

And here is more information on converting to R-134a, they give some 
recommendations: http://www.babcox.com/editorial/ic/ic50034.htm