Listers:
FYI- HERE'S MY 4C ON THIS THREAD:
I have dealt with R-12 and R134 issues in depth during the past two
seasons on various cars. R-12 on my '72 Jaguar E-Type V-12 and my '76
Jensen GT (4 cyl Lotus 907) and my '89 XJS.
On these three I have continued to recharge with R-12- attempting to
seal the leaks with the additive. So far so good. Both blow at @ 45-48^
on a 80+^ day in the sun- after the interior gets to about 75^.
On my Dodge Daytona Shelby ('89) after the original compressor blew- I
cconverted to R134 from R-12. In addition to what other posters have
stated about incompatibility of the two re: oil and seals and
solubility, I've discovered or had cconfirmed some issues one
definitely needs to be cognizant of:
1) a change of the evaporator or filter/dryer is essential- the reason
for this is this unit is where the incompatible oils 'rest'- and
contaminbation will occcur and blow the compressor if it is not changed.
2) A serious and thorough flush is essential, as is evaculation.
Although none of us would in thi day and age of environmental respect-
charge and blast evacuate, the advantage of the evaculation is to ensure
a 'clean and pure' fluid/gas internal system (in the hose , and
associated components of the A/C SYSTEM.
3) IT IS IMPERATIVE NOT TO HAVE TOO MUCH OIL IN THE SYSTEM. SOME NEW
COMPRESSORS COME WITH OIL (AS DID MINE) and the compressor will appear
to lock- screetcch the belt. The 4 Seasons tech guy said to evacuate and
resuce the amount of oil in the system- The oil-when too much can't be
'compr4eessed as it hits the compressor. This happened only on days when
outside temp was 93^ or higher- but we redid the system
4) If the Compressor unit is NOT built or rebuilt by '4 seasons'- the
$89 one's are not the same as those sold for $199 or $299. The
difference is in the warranty. I went with the $299 NAPA unit as others
'in the know' advised the cheaper ones from the low price outlets are
not the same quality built units as the NAPA 4 seasons units.
5) The difference in efficiency is not negligible and 'noticible' as
technically 134 is less efficent. That's why the new 134 cars have
bigger condensors and evaporators- to compensate for the efficeiency
issue. I can get 43-48^ from the R-12 outlets in the XJS E-Type and GT,
, but the R134a in the Dodge will only put out 48^ above 2000RPM and 53^
at idle. On a 100^ day in the sun- you can feel the difference- but the
difference with a working 134 system as opposed to a weak or
non-functional system is still a much better alternative. On the '96 XJR
(R-134-) The system will deliver at 42^ on max cool. So they got it
right on this one!
6) The use of Pressure gauges and/or unit capacity charge
specifications are not the most accurate way to maximize a system. Fill
the system until the metal (not the hoses) begin to show frost- and you
got it- keep in mind a system charged to 'specs' will loose some when
disconnecting - thus after servicing you end up with 'less than spec'.
The 'frost on the metal' way- your at practical max efficiency.
Today the TR was the E-Type's buddy as it went to get antifreeze for the
new coolong hose kit replacement I did on the E-Type. The E got jealous
of the TR and let me know- it literally started to get 'Hot and steamy'
and 'spray a lower cooling hose. It was not about ton hurt itself- as it
did this 6 miles from home, after giving us much pleasure on the 4th (a
87 mile round trip that day). It got muggy and the SUn 'baked' us in the
the TR- glad it was just a 4 mile ride. The Tr was so much fun- we took
her out afterdark to 'smell the honeysuckle' in true TR motoring
tradition!
Hope this helps
Sherman
Sherman D. Taffel
Columbia MD
TR4 and other LBC'c and BBC's
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