refrigerant oil, how much?

["Walter Coe" <Whalt@xxxx>]

Apparently no one knows exactly how much oil belongs in the DeLorean. So
far I have a few clues. The Sanden/Sankyo compressor manufacture specifies
to put 3 to 4 ounces in the compressor. The Haynes techbook supports this
as well as a local wholesale compressor rebuilder who specifies 4 ounces.

Then to figure how much goes in the rest of the system: According to Haynes,
they have a "rule of thumb" guide that suggests 3 ounces for most
accumulators, 3 ounces for the condenser, 1 ounce for the evaporator. Put
it all together with what goes into the compressor and you get 11 ounces!
That seems like way too much. Haynes also suggests measuring what you take
out so that you can put the same amount back in. The flaw with this
approach is that you are assuming that the previous guy did it right. Also
according to Haynes, American made cars that use the same compressor as the
DeLorean take 8 ounces total while foreign cars (expansion valve w/dryer)
take around 4.5 ounces. Since the DeLorean most closely resembles a GM
system (orifice tube w/accumulator), I'm placing my bets that the correct
amount is 8 ounces.

Choosing what kind of refrigerant oil is as confusing as choosing motor oil.
There are at least 3 kinds of PAG, one kind of POE and the old reliable
mineral oil if you are still using R-12. Newer oils claim to be
cross-compatible between R-12 & R-134a. Since they are so incredibly
hygroscopic (similar to how brake fluid is) I think it is a waste of time to
worry about measuring the pH. If you have to open the system up, you might
as well flush it completely and replace it with new oil from a sealed
container.

I just cut open two used DeLorean accumulators today to have a look inside.
One had about 1 ounce of oil in it, and the other had about 1 ounce of
water. And unfortunately, the one with the water was the one that I just
took off my car minutes earlier. $#!+ It took a combination of
heating/cooling/brute force to get the orifice tube connection apart. It
was corroded stuck. Once I got the system flushed with Dura 141, I found a
lot of metal particles. I suppose that the previous owner didn't know or
didn't care enough to add oil and didn't change the accumulator or pull a
vacuum before charging it There apparently was only a few drops of oil in
the system, but I haven't check the compressor yet. I'm REALLY surprised
that I got 2 years & 14K miles out of it. And the system was still working
when I took it apart. The external symptoms were that it was leaking at the
compressor seal and was getting noisy.

Today I put another compressor on, pulled a vacuum that held and everything
went well so far. I charged it to 40psi to make sure the seals were
completely seated and a few minutes later I noticed the pressure steadily
dropping. I got the leak sniffer out and found that the evaporator was
leaking. I'm not surprised since it was so corroded internally and I
stressed the connections a bit getting them apart. (The expansion tube &
outer pipe were bent like a banana before I started.) All of this is
because a previous mechanic didn't care to do it right. And a new
evaporator is going to cost over $400 not to mention my labor & materials.
All of this could have been avoided if they serviced the system properly.

The moral of the story so far: I have seen two DeLorean a/c systems that
were the victim of a bad or dishonest mechanic. And despite this, it can
take several months (or even two years in my case) before the symptoms start
to appear. If an owner didn't know better, he might take it back to the
same jerk and get screwed all over again.

So does anyone have any advice on removing/replacing the evaporator?

Walt Tampa, FL