I’ve always used medium viscosity (100) PAG oil. In fact, many cans of
PAG oil don’t even indicate the viscosity by number.
I do NOT drain the original MINERAL oil out of the compressor.
I do NOT flush the system.
I simply lubricate (with refrigeration oil) any o-rings installed with
new hoses or at the compressor, evacuate the system, add 2 oz. of PAG
oil, add 32 to 36 oz. of R-134a (the original charge of R-12 was 40
oz., and you use less [~80%] R-134a), and enjoy.
Unless you are replacing the compressor for some reason, or have had
some MAJOR catastrophe that has caused loss of much or your
refrigeration oil (more than just oily residue on a slowly leaking
hose), there is no reason to remove the compressor and drain the oil
from its sump to determine how much is there. In fact, most R-134a
conversions from R-12 last better without removing the mineral oil.
Ester oil is used in some systems with R-134a, but AFAIK, it was never
used in a Jaguar R-12 system. I have heard somewhere that you do NOT
want to mix PAG and Ester. Perhaps someone who is more of an expert on
original R-134a systems can comment on that issue.
I hope you still have the mineral oil you drained from the compressor
(so you can measure it), as you need to add back AT LEAST that amount
of some type of refrigeration oil.
Unfortunately, the Jaguar Service Manual is a bit unclear as to how
much oil should be in the compressor sump. On my 1st read of it (in a
hurry) I thought it was stating refill with 10 oz., but upon further
review, that was NOT the case. My recollection is it suggested
something in the 7 to 10 oz. range, but I would encourage you to read
it and try to make your own decision.
If anyone else has a particular opinion on that issue, please provide
it and the basis (manual, etc.) for that opinion.
Be aware that if you flush or empty all the oil out of the system in
some manner, you need to add new refrigeration oil based upon the
components replaced or flushed (see the Jaguar Service Manual for oil
amount per component).
Don’t make this job harder than it needs to be. The most critical part
of the job is the amount and type of refrigeration oil used or
replaced, as your compressor will quickly fail if not properly
BTW, I seem to remember that you or another post mentioned earlier
something about not having a switch in the rear of the compressor. One
should NEVER run a system without the proper compressor clutch cutout
AFAIK, NO Jaguar system used a TWO-WIRE switch, so perhaps someone sold
you the wrong part. There were, however, two different clutch cutout
(1) the system used through about 1987 used a thermal fuse (with 3
wires) mounted on the front plate of the compressor near the clutch,
and there was a “superheat switch,” part# AEU1688/J, on the rear of the
compressor that would cause the thermal fuse to burn out and disconnect
the ground to the compressor clutch, if system pressure fell too low.
(2) beginning ~ 1988 models, a HSLP switch was used which provided
ground to the compressor clutch as long as low side pressure was
AFAIK, although located in the same place on the rear of the
compressor, the Superhear Switch is NOT the same as the HSLP (High Side
Low Pressure) switch used from ~ 1988 on (basically changed at or about
the time the change was made from Delanair II to Delanair III systems).
Even though many of the components on the Jaguar A/C system are the
same as GM 70’s and 80’s systems, for some reason many good parts
chains such as NAPA have incorrect catalogue information (they even
list the Sanden compressor for mid- to late-80’s 5.3L XJ-S models with
the A-6), and you need to know what your system requires, based upon
parts visual comparisons, parts catalogue information, or if you’re not
sure, relying on trusted Jag parts suppliers such as CW, Motorcars, etc.
George Balthrop, Clifton, VA USA
89 and 85 XJ-S Coupes; 89 XJ40 VDP-----Original Message-----
From: Don Franke firstname.lastname@example.org
Have been doing a search on A6 compressor when converting from R12
to 134A and have seen three different opinions as to the PAG oil
Did not measure the quantity of oil
removed from the compressor.
Need to do more learning as to how to
properly flush the evaporator and the condenser.
Don’t know if the
ester oil remaining in those two components must be flushed out
completely or if the system will perform and last if some remains
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