I'm looking for good information/advice on AC.  I have an '86 Syncro with a
Sanden 510 Compressor (I think that the number - it's the big 5 cylinder
one - I know, I had to replace it).  I  just had to replace the main high
pressure hose and get the system flushed and refilled.  Still R-12 since I
need the efficiency - I live where it's hot, Las Vegas.  Anyway, the AC
repair place - supposedly the best one in town, is not inclined to put the
full 50.75 oz. of R-12 in called for in Bentley.  First they put in about
2.5 lbs, and today another 6-8 oz.  The uncertainty is due to the way they
measure - they say their eqiupment times the injection length and they
compute from that, but aren't exactly sure what that gives them.  What they
do do is watch head pressures.  Today, about 80 Fahrenheit ambient, the head
pressure after the addition was 225 psig.  They told me it would probably
get up to 250 psig when temperatures climb over 100.  They say this is as
high as they want to push it.  The previous place had been pushing it up to
300 psig.  Bentley doesn't say.  It works good now, but it always does under
100 degrees.  It's over 100 that it really needs the best efficiency.
Anybody know the answer??