I found this that tells how to fill a Nissan. Happens to be the same R134 capacity as the SVX.
http://www.sadik.net/nissan/howto/ac_r134.htm
This has info on the low pressure gauge readings and if the system has been apart
http://www.instructables.com/id/SWUERP3FDHGJTGK/
The vacuum test is also a leak test. When the system can't hold vacuum there could be a leak somewhere.
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