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Old 04-16-2011, 01:35 PM
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vstech vstech is offline
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 26,353
Originally Posted by Manual Life View Post
This thread exploded. In the case that you already did not know, I know virtually nothing about a/c systems. And, I had a tech from Aamco do the work. We did it at his house because he had everything required.

He added 2 oz. of a/c oil after the system was evacuated. Following the oil he added the 134.

When I say "0" I mean on the evacuation. Without oil the there was not a full evacuation.

As is, I'll go ahead and test the system with dye and go from there. In the meantime search for R-12
let's start over.
the oil was added to a functional system, or was the system cleaned out first?
zero on a refrigeration manifold gauge is open to the atmosphere. or simply pressure removed.
a properly evacuated a/c system will read pegged to 29" on the lower scale of the compound gauge. not zero.
and that is NOT the limit of the scale, at 28.9 inches of mercury, vacuum there are microns of scale between it and 29.2" perfect vacuum. I like to shoot for stable 1000 microns in automotive evacuation that will hold.
it's REALLY hard to go lower than 1000 in a semiherm system. it's nearly impossible in a leaking system to get it below 2000 microns. and it will not stay there long. oil can slow the movement of atmosphere into the system through the pores in the lines, and the spaces between the seals. but just adding oil to the system will not move it around enough to do it. it's gotta be fed through an operating system to spread.

Unless you are discussing scientific gauges...
then: One Atmosphere = 14.7 PSIA = 0.0 PSIG

Perfect Vacuum = 0.0 PSIA = - 14.7 PSIG
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Last edited by vstech; 04-18-2011 at 01:37 AM. Reason: corrections, thanks to MattL etc...
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