hey dude eric is right , and you will still have to pull a vac on the
system, if not you will first clog the expansion valve, second in the long
run ruin the compressor,and all this; still while you have a leak,also the
year model van you have, and I lived this nightmare is that the inside of
the refig hoses are splitting and falling apart , and i bet on a 9 out of
10 , that those hoses are bad,. Do it right the first time, not to mention
that the system needs to be flushed, r-12 oil DOES NOT MIX with r134a
oil ......

You are wasting your time , and money by not doing it right, If not it
will cost you more down the road....your mechanic will love you
though....and summer is almost over